DS1E-M-DC1.5V-R

Relay Technical Information Definition of Relay Terminology COIL (also referred to as primary or input) • Nominal Operating Power The value of power used by the coil at nominal voltage. For DC coils expressed in watts; AC expressed as volt amperes. Nominal Power (W or VA) = Nominal Voltage × Nominal Current. • Coil Resistance This is the DC resistance of the coil in DC type relays for the temperature conditions listed in the catalog. (Note that for certain types of relays, the DC resistance may be for temperatures other than the standard 20°C 68°F.) decreased, the value at or above which all contacts must revert to their unoperated position. • Maximum Continuous Voltage The maximum voltage that can be applied continuously to the coil without causing damage. Short duration spikes of a higher voltage may be tolerable, but this should not be assumed without first checking with the manufacturer. • Nominal Operating Current The value of current flow in the coil when nominal voltage is impressed on the coil • Nominal Coil Voltage (Rated Coil Voltage) A single value (or narrow range) of source voltage intended by design to be applied to the coil or input. • Pick-Up Voltage (Pull-In Voltage or Must Operate Voltage) As the voltage on an unoperated relay is increased, the value at or below which all contacts must function (transfer). • Drop-Out Voltage (Release or Must Release Voltage) As the voltage on an operated relay is • Coil Designation Single side stable type Non-polarized Polarized + 1 coil latching type — 2 coil latching type 4-terminal + + 3-terminal + or + — A black coil represents the energized state. For latching relays, schematic — — + — — or — + diagrams generally show the coil in its reset state. Therefore, the coil symbol is also shown for the reset coil in its reset state. amperes (AC) which can safely be switched by the contacts. This value is the product of switching voltage x switching current, and will be lower than the maximum voltage and maximum current product. • Maximum Switching Voltage The maximum open circuit voltage which can safely be switched by the contacts. AC and DC voltage maximums will differ in most cases. • Maximum Switching Current The maximum current which can safely be switched by the contacts. AC and DC current maximums may differ. • Maximum Switching Power The upper limit of power which can be switched by the contacts. Care should be taken not to exceed this value. • Maximum Carrying Current The maximum current which after closing or prior to opening, the contacts can safely pass without being subject to temperature rise in excess of their design limit, or the design limit of other temperature sensitive components in the relay (coil, springs, insulation, etc.). This value is usually in excess of the maximum switching current. • Minimum switching capability This value is a guideline as to the lowest possible level at which it will be possible for a low level load to allow switching. The level of reliability of this value depends on switching frequency, ambient conditions, change in the desired contact resistance, and the absolute value. Please use a relay with AgPd contacts if your needs analog low level loads, control, or a contact resistance of 100 mΩ or less. We recommend that you verify with one of our sales offices regarding usage. • Maximum Switching Capacity This is listed in the data column for each type of relay as the maximum value of the contact capacity and is an interrelationship of the maximum switching power, maximum switching voltage, and maximum switching current. The switching current and switching voltage can be obtained from this graph. For example, if the switching voltage is fixed in a certain application, the maximum switching current can be obtained from the intersection between the voltage on the axis and the maximum switching power. CONTACTS (secondary or output) • Contact Forms Denotes the contact mechanism and number of contacts in the contact circuit. • Contact Symbols Form A contacts (normally open contacts) Form B contacts (normally closed contacts) Form C contacts (changeover contacts) Form A contacts are also called N.O. contacts or make contacts. Form B contacts are also called N.C. contacts or break contacts. Form C contacts are also called changeover contacts or transfer contacts. • MBB Contacts Abbreviation for make-before-break contacts. Contact mechanism where Form A contacts (normally open contacts) close before Form B contacts open (normally closed contacts). • Rated Switching Power The design value in watts (DC) or volt All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Definition of Relay Terminology Maximum Switching Capacity (TX relay) Example: Using TX relay at a switching voltage of 60V DC, the maximum switching current is 1A. (Maximum switching capacity is given for a resistive load. Be sure to carefully check the actual load before use.) • Contact Resistance This value is the combined resistance of the resistance when the contacts are touching each other, the resistance of the terminals and contact spring. The contact resistance is measured using the voltagedrop method as shown below. The measuring currents are designated in Fig. 1. Switching current, A 3.0 2.0 V DC resistive load 1.0 Measured contact 0.5 0.4 0.3 R A 0.2 A : Ammeter V : 0 20 30 50 100 200 300 Contact voltage, V Power source (AC or DC) Test Currents Rated Contact Current or Switching Current (A) Test Current (mA) Less than 0.01 1 0.01 or more and less than 0.1 10 0.1 or more and less than 1 100 1 or more 1,000 The resistance can be measured with reasonable accuracy on a YHP 4328A milliohmmeter. In general, for relays with a contact rating of 1A or more, measure using the voltagedrop method at 1A 6V DC. • Capacitance This value is measured between the terminals at 1kHz and 20°C 68°F. Voltmeter R : Variable resister Fig. 1 PERFORMANCE • Insulation Resistance The resistance value between all mutually isolated conducting sections of the relay, i.e. between coil and contacts, across open contacts and between coil or contacts to any core or frame at ground potential. This value is usually expressed as “initial insulation resistance” and may decrease with time, due to material degradation and the accumulation of contaminants. • Breakdown Voltage (Hi-Pot or Dielectric Strength) The maximum voltage which can be tolerated by the relay without damage for a specified period of time, usually measured at the same points as insulation resistance. Usually the stated value is in VAC (RMS) for one minute duration. • Surge Withstand Voltage The ability of the device to withstand an abnormal externally produced power surge, as in a lightning strike, or other phenomenon. An impulse test waveform is usually specified, indicating rise time, peak value and fall time. (Fig. 2) 1,500 V 750 V 10 µs 160 µs Fig. 2 • Operate Time (Pull-In or Pick-Up Time) The elapsed time from the initial application of power to the coil, until the closure of the normally open contacts. (With multiple pole devices the time until the last contact closes.) This time does not include any bounce time. • Release Time (Drop-Out Time) The elapsed time from the initial removal of coil power until the reclosure of the normally closed contacts (last contact with multi-pole) this time does not include bounce. • Set Time Term used to describe operate time of a latching relay. • Reset Time Term used to describe release time of a latching relay. With a 2-coil magnetic latching relay the time is from the first application of power to the reset coil until the reclosure of the reset contacts. With a single coil latching relay, the time is measured from the first application of reverse coil voltage until the reclosure of the reset contact. • Contact Bounce (Time) Generally expressed in time (ms), this refers to the intermittent switching phenomenon of the contacts which occurs due to the collision between the movable metal parts or contacts, when the relay is operated or released. • Operate Bounce Time The time period immediately following operate time during which the contacts are still dynamic, and ending once all bounce has ceased. • Release Bounce Time The time period immediately following release time during which the contacts are still dynamic, ending when all bounce has ceased. • Shock Resistance, Destructive The acceleration which can be withstood by the relay during shipping or installation without it suffering damage, and without causing a change in its operating characteristics. Usually expressed in “G”s. • Shock Resistance, Functional The acceleration which can be tolerated by the relay during service without causing the closed contacts to open for more than the specified time. (usually 10µs) • Vibration Resistance, Destructive The vibration which can be withstood by the relay during shipping, installation or use without it suffering damage, and without causing a change in its operating characteristics. Expressed as an acceleration in G’s or displacement, and frequency range. • Vibration Resistance, Functional The vibration which can be tolerated by the relay during service, without causing the closed contacts to open for more than the specified time. • Mechanical Life The minimum number of times the relay can be operated under nominal conditions (coil voltage, temperature, humidity, etc.) with no load on the contacts. • Electrical Life The minimum number of times the relay can be operated under nominal conditions with a specific load being switched by the contacts. • Maximum Switching Frequency This refers to the maximum switching frequency which satisfies the mechanical life or electrical life under repeated operations by applying a pulse train at the rated voltage to the operating coil. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Definition of Relay Terminology HIGH FREQUENCY CHARACTERISTICS • Life Curve This is listed in the data column for each type of relay. The life (number of operations) can be estimated from the switching voltage and switching current. For example, for a DS relay operating at: Switching voltage = 125V AC Switching current = 0.6A The life expectancy is 300,000 operations. However, this value is for a resistive load. Be sure to carefully check the actual load before use. Life Curve • Isolation High frequency signals leak through the stray capacitance across contacts even if the contacts are separated. This leak is called isolation. The symbol dB (decibel) is used to express the magnitude of the leak signal. This is expressed as the logarithm of the magnitude ratio of the signal generated by the leak with respect to the input signal. The larger the magnitude, the better the isolation. • Insertion Loss At the high frequency region, signal disturbance occurs from self-induction, resistance, and dielectric loss as well as from reflection due to impedance mismatching in circuits. Loss due to any of these types of disturbances is called insertion loss. Therefore, this refers to the magnitude of loss of the input signal. The smaller the magnitude, the better the relay. Life (×104) 1,000 30V DC resistance load 100 125V AC resistance load 10 1 • V.S.W.R. (Voltage Standing Wave Ratio) High frequency resonance is generated from the interference between the input signal and reflected (wave) signal. V.S.W.R. refers to the ratio of the maximum value to minimum value of the waveform. The V.S.W.R. is 1 when there is no reflected wave. It usually becomes greater than 1. Notes: 1. Except where otherwise specified, the tests above are conducted under standard temperature and humidity (15°C to 35°C 59°F to 95°F, 25 to 75%). 2. The coil impressed voltage in the switching tests is a rectangular wave at the rated voltage. 3. The phase of the AC load operation is random. 2 Current (A) PROTECTIVE CONSTRUCTION contamination, and also may protect user personnel from a shock hazard. • Flux-Resistant Type In this type of construction, solder flux penetration is curtailed by either insert molding the terminals with the header, or by a simple sealing operation during manufacturing. • Sealed Type This type of sealed relay totally excludes the ingress of contaminants by way of a sealing compound being applied to the header/cover interface. The constituent components are annealed for physical Several different degrees of protection are provided for different relay types, for resistance to dust, flux, contaminating environments, automatic cleaning, etc. • Open Type For reasons of cost, some devices are not provided with any enclosure. It is usually assumed that the end application will be in an overall enclosure or protective environment. • Dust Cover Type Most standard relays are provided with a dust cover of some type. This protects the relay from large particulate and chemical stability. This annealing process drives off residual volatiles in the plastics, insuring a contaminant free environment inside the sealed relay, resulting in more stable contact resistance over life. • Hermetic Seal The plastic sealed type is not a true hermetic seal, there is an exchange of gas molecules through the plastic cover over time. The only true hermetic seals are metal to metal and glass to metal. The entire device is purged with dry nitrogen gas prior to sealing, improving reliability. CONSTRUCTION AND CHARACTERISTIC Type Construction Characteristics Automatic Soldering Automatic Cleaning Harmful Gas Resistance Most basic construction where the case and base (or body) are fitted together.    Terminals are sealed or molded simultaneously. The joint between the case and base is higher than the surface of the PC board.    Terminals, case, and base are filled with sealing resin.    Hermetically sealed with metal case and metal base. Terminals are sealed with glass.    ;;;;; Dust Cover Type (: Yes, : No) Base Flux-Resistant Type Base Sealed Type Sealing resin Metal case Metallic Hermetic Seal Type Glass Metal base All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Definition of Relay Terminology OPERATIONAL FUNCTION • 2 Coil Latching Type Relay with a latching construction composed of 2 coils: set coil and reset coil. The relay is set or reset by alternately applying pulse signals of the same polarity. (Fig. 5) • Single Side Stable Type Relay which turns on when the coil is energized and turns off when deenergized. (Fig. 3) + – 1 3 4 5 12 10 9 8 Direction indication* TX relay Fig. 3 • 1 Coil Latching Type Relay with a latching construction that can maintain the on or off state with a pulse input. With one coil, the relay is set or reset by applying signals of opposite polarities. (Fig. 4) – + 1 3 4 5 12 10 9 8 1 3 4 5 6 + – + – 12 10 9 8 7 • Operation Indication Indicates the set and reset states either electrically or mechanically for easy maintenance. An LED wired type (LED wired HC relay), lamp type (lamp wired HP relay) are available. (Fig. 6) Direction indication* Fig. 5 LED wired HC relay TX relay Fig. 6 Direction indication* Fig. 4 TX relay TERMINAL CONFIGURATION Type PC board through hole terminal PC board self-clinching terminal GQ, GN, TQ, TN, TK, TX, TX-D relay, DS relay, DS-BT relay, RP relay, JS relay, JW relay, SEB relay, JQ relay, PQ relay TQ, TN, TK, TX, TX-D relay PC board surface-mount terminal Plug-in terminal Quick connect terminal Screw terminal Typical relay type Terminal configuration GQ-SMD, GN-SMD, TX-SMD, TQ-SMD HJ relay, HC relay HP relay, HE relay HL relay, HK relay HN relay JC relay JR relay HE relay EP relay EJ relay ; ; ; ; ;; ; Typical relay type MOUNTING METHOD Type Insertion mount Surface mount Socket mount Terminal socket mount Mounting configuration TM relay TMP type Terminal Socket Typical relay type GQ, GN, TQ, TN, TK, TX, TX-D relay, DS relay, DS-BT relay, RP relay, SEB relay GQ-SMD, GN-SMD, TX-SMD, TQ-SMD NC relay HC relay HL relay HJ relay, HC relay HP relay, HG relay HL relay, HK relay HN relay Notes: 1. Sockets are available for certain PC board relays. (SEB relay, ST relay, etc.) 2. M type (solder type) for direct screw mounting of case is also available. (HG relay) All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. HC relay JR relay JC relay JR relay LF relay JT-N relay General Application Guidelines A relay may encounter a variety of ambient conditions during actual use resulting in unexpected failure. Therefore, testing over a practical range under actual operating conditions is necessary. Application considerations should be reviewed and determined for proper use of the relay. CAUTIONS REGARDING SAFETY turn off the power when installing, maintaining and troubleshooting the relay (including connecting parts such as the terminal block and socket). • Perform terminal connections correctly after verifying the internal wiring diagrams in the catalog. Connecting incorrectly may cause unexpected malfunction, abnormal • Be absolutely sure not to exceed the specification ranges, such as coil rating, contact rating and switching life. Doing so may lead to abnormal heating, smoke, and fire. • Be absolutely sure not to touch the charging part when the relay is on. Doing so may cause electrical shock. Be sure to heating, and fire, etc. • Prepare with a redundant safety device construction if there is a possibility that such things as adhesion, contact failure or disconnection could cause bodily harm or property damage. METHOD OF DETERMINING SPECIFICATIONS Failsafe Specification item a) b) c) d) e) f) g) h) 1) Select relay with consideration for power source ripple. 2) Give sufficient consideration to ambient temperature, for the coil temperature rise and hot start. 3) When used in conjunction with semiconductors, additional attention to the application should be taken. a) b) c) d) e) f) Contact arrangement Contact rating Contact material Life Contact pressure Contact resistance 1) It is desirable to use a standard product with more than the required number of contacts. 2) It is beneficial to have the relay life balanced with the life of the device it is used in. 3) Is the contact material matched to the type of load? It is necessary to take care particularly with low level usage. 4) The rated life may become reduced when used at high temperatures. Life should be verified in the actual atmosphere used. 5) Depending on the circuit, the relay drive may synchronize with the AC load. As this will cause a drastic shortening of life should be verified with the actual machine. a) b) c) d) a) b) c) d) Operate time Release time Bounce time Switching frequency Vibration resistance Shock resistance Ambient temperature Life Coil Contacts Operate time Mechanical characteristics Other items Consideration points regarding selection Rating Pick-up voltage (current) Drop-out voltage (current) Maximum continuous impressed voltage (current) Coil resistance Impedance Temperature rise Input frequency for AC type a) Mounting method b) Cover c) Size 1) It is beneficial to make the bounce time short for sound circuits and similar applications. 1) Give consideration to performance under vibration and shock in the use location. 2) In particular, when used in high temperature applications, relay with class B or class F coil insulation may be required. 1) Selection can be made for connection method with plug-in type, printed circuit board type, soldering, tab terminals, and screw fastening type. 2) For use in an adverse atmosphere, sealed construction type should be selected. 3) Are there any special conditions? BASICS ON RELAY HANDLING • To maintain initial performance, care should be taken to avoid dropping or hitting the relay. • Under normal use, the relay is designed so that the case will not detach. To maintain initial performance, the case should not be removed. Relay characteristics cannot be guaranteed if the case is removed. • Use of the relay in an atmosphere at standard temperature and humidity with minimal amounts of dust, SO2 , H2 S, or organic gases is recommended. • Please avoid the use of silicon-based resins near the relay, because doing so may result in contact failure. (This applies to plastic sealed type relays, too.) • Care should be taken to observe correct coil polarity (+, –) for polarized relays. • Proper usage requires that the rated voltage be impressed on the coil. Use rectangular waves for DC coils and sine waves for AC coils. • Be sure the coil impressed voltage does not continuously exceed the maximum allowable voltage. • Absolutely avoid using switching voltages and currents that exceed the designated values. • The rated switching power and life are given only as guides. The physical phenomena at the contacts and contact life greatly vary depending on the type of load and the operating conditions. Therefore, be sure to carefully check the type of load and operating conditions before use. • Do not exceed the usable ambient temperature values listed in the catalog. • Use the flux-resistant type or sealed type if automatic soldering is to be used. • Use alcohol based cleaning solvents when cleaning is to be performed using a sealed type relay. • Avoid ultrasonic cleaning of all types of relays. • Avoid bending terminals, because it may cause malfunction. • As a guide, use a Faston mounting pressure of 40 to 70N {4 to 7kgf}for relays with tab terminals. • For proper use, read the main text for details. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines PROBLEM POINTS WITH REGARD TO USE In the actual use of relays, various ambient conditions are encountered, and because unforeseen events occur which can not be thought of on the drawing board, with regard to such conditions, tests are necessary under the possible range of operation. For example, consideration must always be given to variation of performance when relay characteristics are being reviewed. The relay is a mass production item, and as a matter of principle, it must be recognized that the relay is to be used to the extent of such variations without the need for adjustment. resistance due to temperature rise, must be given consideration for the worst possible condition of relay operation, making it necessary to consider the current value as 1.5 to 2 times the pick-up current. Also, because of the extensive use of relays as limit devices in place of meters for both voltage and current, and because of the gradual increase or decrease of current impressed on the coil causing possible delay in movement of the contacts, there is the possibility that the designated control capacity may not be satisfied. Thus it is necessary to exercise care. The DC type relay coil resistance varies due to ambient temperature as well as to its own heat generation to the extent of about 0.4%/°C, and accordingly, if the temperature increases, because of the increase in pic k-up and drop-out voltages, care is required. • Energizing voltage of AC coil In order to have stable operation of the relay, the energizing voltage should be basically within the range of +10%/-15% of the rated voltage. However, it is necessary that the waveform of the voltage impressed on the coil be a sine wave. There is no problem if the power source is commercially provided power, but when a stabilized AC power source is used, there is a waveform distortion due to that equipment, and there is the possibility of abnormal overheating. By means of a shading coil for the AC coil, humming is stopped, but with a distorted waveform, that function is not displayed. Fig. 1 below shows an example of waveform distortion. If the power source for the relay operating circuit is connected to the same line as motors, solenoids, transformers, and other loads, when these loads operate, the line voltage drops, and because of this the relay contacts suffer the effect of vibration and subsequent burn damage. In particular, if a small type transformer is used and its capacity has no margin of safety, when there is long wiring, or in the case of household used or small sales shop use where the wiring is slender, it is necessary to take precautions because of the normal voltage fluctuations combined with these other factors. When trouble develops, a survey of the voltage situation should be made using a synchroscope or similar means, and the necessary counter-measures should be taken, and together with this determine whether a special relay with suitable excitation characteristics should be used, or make a change in the DC circuit as shown in Fig. 2 in which a capacitor is inserted to absorb the voltage fluctuations. In particular, when a magnetic switch is being used, because the load becomes like that of a motor, depending upon the application, separation of the operating circuit and power circuit should be tried and investigated. RELAY COIL • AC operation type For the operation of AC relays, the power source is almost always a commercial frequency (50 or 60Hz) with standard voltages of 6, 12, 24, 48, 115, and 240V AC. Because of this, when the voltage is other than the standard voltage, the product is a special order item, and the factors of price, delivery, and stability of characteristics may create inconveniences. To the extent that it is possible, the standard voltages should be selected. Also, in the AC type, shading coil resistance loss, magnetic circuit eddy current loss, and hysteresis loss exit, and because of lower coil efficiency, it is normal for the temperature rise to be greater than that for the DC type. Furthermore, because humming occurs when below the pick-up voltage and when above the rated voltage, care is required with regard to power source voltage fluctuations. For example, in the case of motor starting, if the power source voltage drops, and during the humming of the relay, if it reverts to the restored condition, the contacts suffer a burn damage and welding, with the occurrence of a false operation self-maintaining condition. For the AC type, there is an inrush current during the operation time (for the separated condition of the armature, the impedance is low and a current greater than rated current flows; for the adhered condition of the armature, the impedance is high and the rated value of current flows), and because of this, for the case of several relays being used in parallel connection, it is necessary to give consideration to power consumption. • DC operation type For the operation of DC relays, standards exist for power source voltage and current, with DC voltage standards set at 5, 6, 12, 24, 48, and 100V, but with regard to current, the values as expressed in catalogs in milliamperes of pick-up current. However, because this value of pick-up current is nothing more than a guarantee of just barely moving the armature, the variation in energizing voltage and resistance values, and the increase in coil Sine wave Approximate keystone wave Waveform with a this harmonic included Fig. 1 Distortion in an AC stabilized power source T Switch 100V AC 24V DC Fig. 2 Voltage fluctuation absorbing circuit using a condenser All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. C R Relay coil General Application Guidelines • Power source for DC input As a power source for the DC type relay, a battery or either a half wave or full wave rectifier circuit with a smoothing capacitor is used. The characteristics with regard to the excitation voltage of the relay will change depending upon the type of power source, and because of this, in order to display stable characteristics, the most desirable method is perfect DC. In the case of ripple included in the DC power source, particularly in the case of half wave rectifier circuit with a smoothing capacitor, if the capacity of the capacitor is too small, due to the influence of the ripple, humming develops and an unsatisfactory condition is produced. With the actual circuit to be used, it is absolutely necessary to confirm the characteristics. (Fig. 3) With regard to our T-Series (TQ, TN, TK, TX, TX-D, TQ-SMD) and SEB relays, it is necessary to give consideration to the use of a power source with less than a 5% ripple, but for the J series, NC relays, there is no hindrance to the operation. However, the pull-up force becomes somewhat weakened, and it is necessary to take care since the resistance to vibration and shock is reduced. Also ordinarily the following must be given thought. ~ R Relay Smoothing capacitor Ripple portion Emax. Emin. Ripple percentage = Emax.–Emin ×100% Emean. Fig. 3 DC portion Emean. Emax. = Maximum value of ripple portion Emin. = Minimum value of ripple portion Emean. = Average value of ripple portion [4] Coil applied voltage and the drop in voltage. Please verify that the actual voltage is applied to the coil at the actual load. Electrical life will be affected by the drop in voltage in the coil when load is turned on. • Coil temperature rise In addition to being a requirement for relay operation stability, the maximum continuous impressed coil voltage is an important constraint for the prevention of such problems as thermal deterioration or deformity of the insulation material, or the occurrence of fire hazards. In actual use with E-type insulation, when the ambient temperature is 40°C 104°F, a temperature rise limit of 80°C 176°F is thought to be reasonable according to the resistance method. However, when complying with the Electrical Appliance and Material Safety Law, this becomes 75°C 167°F. • Temperature rise due to pulse voltage When a pulse voltage with ON time of less than 2 minutes is used, the coil temperature rise bares no relationship to the ON time. This varies with the ratio of ON time to OFF time, and compared with continuous current passage, it is rather small. The various relays are essentially the same in this respect. (Fig. 4) • Pick-up voltage change due to coil temperature rise (hot start) In DC relays, after continuous passage of current in the coil, if the current is turned OFF, then immediately turned ON again, due to the temperature rise in the coil, the pick-up voltage will become somewhat higher. Also, it will be the same as using it in a higher temperature atmosphere. The resistance/temperature relationship for copper wire is about 0.4% for 1°C, and with this ratio the coil resistance increases. That is, in order to operate of the relay, it is necessary that the voltage be higher than the pick-up voltage and the pick-up voltage rises in accordance with the increase in the resistance value. However, for some polarized relays, this rate of change is considerably smaller. • Operate time In the case of AC operation, there is extensive variation in operate time depending upon the point in the phase at which the switch is turned ON for coil excitation, and it is expressed as a certain range, but for miniature types it is for the most part 1/2 cycle (about 10ms). However, for the somewhat large type relay where bounce is large, the operate time is 7 to 16ms, with release time in the order of 9 to 18ms Also, in the case of DC operation, to the extent of large coil input, the operating time is rapid, but if it is too rapid, the “A” contact bounce time is extended. • Stray circuits (bypass circuits) In the case of sequence circuit construction, because of bypass flow or alternate routing, it is necessary to take care not to have erroneous operation or abnormal operation. To understand this condition while preparing sequence circuits, as shown in Fig. 5, with 2 lines written as the power source lines, the upper line is always B and the lower line v (when the circuit is AC, the same thinking applies). Accordingly the B side is necessarily the side for making contact connections (contacts for relays, timers, limit switches, etc.), and the v side is the Current passage time For continuous passage Voltage ON : OFF = 3 : 1 ON : OFF = 1 : 1 ON : OFF = 1 : 3 % Temperature rise value is 100% About 80% About 50% About 35% 1:1 Time Fig. 4 Load [1] It is desirable to have less than a 5% ripple for the reed type relay. [2] For the hinge type relay, a half wave rectifier cannot be used, alone unless you use a smoothing capacitor. The ripple and the characteristics must be evaluated for proper usage. [3] For the hinge type relay, there are certain applications that may or maynot use the full wave rectifier on it’s own. Please check specifications with the original manufacture. Shown on the right, is a circuit driven by the same power supply (battery, etc.) for both the coil and contact. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines load circuit side (relay coil, timer coil, magnet coil, solenoid coil, motor, lamp, etc.). correctly made. In addition, with regard to the DC circuit, because it is simple by means of a diode to prevent stray circuits, proper application should be made. a series circuit through A, R1, R2, and R3, and the relays will hum and sometimes not be restored to the drop out condition. The connections shown in Fig. 6 (b) are Upper side line Contact circuit Power source lines R A Load circuit B C D Lower side line R1 R2 R3 A B Fig. 5 Example of a vertically written sequence circuit Fig. 6 shows an example of stray circuits. In Fig. 6 (a), with contacts A, B, and C closed, after relays R1, R2, and R3 operate, if contacts B and C open, there is • Gradual increase of coil impressed voltage and suicide circuit When the voltage impressed on the coil is increased slowly, the relay transferring operation is unstable, the contact pressure drops, contact bounce increases, and an unstable condition of contact occurs. This method of applying voltage to the coil should not be used, and consideration should be given to the method of impressing voltage on the coil (use of switching circuit). Also, in the case of latching relays, using self contacts “B,” the method of self coil circuit for complete interruption is used, but because of the possibility of trouble developing, care should be taken. The circuit shown in Fig. 7 causes a timing and sequential operation using a reed type relay, but this is not a good example • Phase synchronization in AC load switching If switching of the relay contacts is synchronized with the phase of the AC power, reduced electrical life, welded contacts, or a locking phenomenon (incomplete release) due to contact material transfer may occur. Therefore, check the relay while it is operating in the actual system. When driving relays with timers, micro computers and thyristors, etc., there may be synchronization with the power supply phase. (Fig. 8) • Erroneous operation due to inductive interference For long wire runs, when the line for the control circuit and the line for power line use a single conduit, induction voltage, caused by induction from the power line, will be applied to the operation coil regardless of whether or not the control signal is off. In this case the relay and timer may not revert. Therefore, when wiring spans a long distance please remember that along with inductive interference, connection failure may be R2 R1 C (a) Not a good example R3 (b) Correct example Fig. 6 Stray circuits with mixture of gradual increase of impressed voltage for the coil and a sucide circuit. In the timing portion for relay R1, when the timing times out, chattering occurs causing trouble. In the initial test (trial production), it shows favorable operation, but as the number of operations increases, contact blackening (carbonization) plus the chattering of the relay creates instability in performance. Instability point Switch R1 a R2a R1 b R2b X X SW ON E C R1 C e R2 R1 b R1 a R1: Reed relay R2: Reed relay R1a: Form A of relay R1 R1b: Form B of relay R1 C: Capacitor X: Variable resistance (for time adjustment) Fig. 7 A timing and sequential operation using a reed type relay Ry Vin. Load Load voltage Vin. Fig. 8 caused by a problem with distribution capacity or the device might break down due to the influence of externally caused surges, such as that caused by lightning. • Long term current carrying A circuit designed for non-excitation when left running is desirable for circuits (circuits for emergency lamps, alarm devices and error inspection that, for example, revert only during malfunction and output warnings with form B contacts) that will be carrying a current continuously for long periods without relay switching operation. Continuous, long-term current to the coil will facilitate deterioration of coil insulation and characteristics due to heating of the coil itself. For circuits such as these, please use a magnetic-hold type latching relay. If you must use a single stable relay, use a sealed type relay that is not easily affected by ambient conditions and provide a failsafe circuit design that considers the possibility of contact failure or disconnection. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines (2) When a grounding is not required, connect the ground terminal to the B side of the coil. (Refer to Fig. 11) (NF and NR with ground terminal) [3] When the v side of the power source is grounded, always avoid interting the contacts (and switches) in the v side. (Refer to Fig. 12) (Common to all relays) [4] In the case of relays provided with a ground terminal, when the ground terminal is not considered effective, not making a connection to ground plays an Judgement: Good (Fig. 9) important role as a method for preventing electrolytic corrosion. Note: The designation on the drawing indicates the insertion of insulation between the iron core and the chassis. In relays where a ground terminal is provided, the iron core can be grounded directly to the chassis, but in consideration of electrolytic corrosion, it is more expedient not to make the connection. Judgement: Good (Fig. 10) Switch – – + + Iron core Relay coil + – Judgement: Good (Fig. 11) + – Iron core Relay coil Start of coil winding R (Insulation resistance) Switch Bobbin End of coil winding ;;;; ;;; ; Bobbin R (Insulation resistance) Judgement: No good (Fig. 12) Switch – + + Relay coil Iron core + – Bobbin ;;; ; Bobbin + ;;;; • Usage with infrequent switching Please carry out periodic contact conductivity inspections when the frequency of switching is once or fewer times per month. When no switching of the contacts occurs for long periods, organic membrane may form on the contact surfaces and lead to contact instability. • Regarding electrolytic corrosion of coils In the case of comparatively high voltage coil circuits (in particular above 48 V DC), when such relays are used in high temperature and high humidity atmospheres or with continuous passage of current, the corrosion can be said to be the result of the occurrence of electrolytic corrosion. Because of the possibility of open circuits occurring, attention should be given to the following points. [1] The B side of the power source should be connected to the chassis. (Refer to Fig. 9) (Common to all relays) [2] In the case where unavoidably the v side is grounded, or in the case where grounding is not possible. (1) Insert the contacts (or switch) in the B side of the power source, and connect the start of the coil winding the v side. (Refer to Fig. 10) (Common to all relays) + Relay coil Switch – Iron core R (Insulation resistance) CONTACT The contacts are the most important elements of relay construction. Contact performance conspicuously influenced by contact material, and voltage and current values applied to the contacts (in particular, the voltage and current waveforms at the time of application and release), the type of load, frequency of switching, ambient atmosphere, form of contact, contact switching speed, and of bounce. Because of contact transfer, welding, abnormal wear, increase in contact resistance, and the various other damages which bring about unsuitable operation, the following items require full investigation. *We recommend that you verify with one of our sales offices. 1. Contact circuit voltage, current, and load [Voltage, AC and DC] When there is inductance included in the circuit, a rather high counter emf is generated as a contact circuit voltage, and since, to the extent of the value of that voltage, the energy applied to the contacts causes damage with consequent wear of the contacts, and transfer of the contacts, it is necessary to exercise care with regard to control capacity. In the case of DC, there is no zero current point such as there is with AC, and accordingly, once a cathode arc has been generated, because it is difficult to quench that arc, the extended time of the arc is a major cause. In addition, due to the direction of the current being fixed, the phenomenon of contact shift, as noted separately below, occurs in relation to the contact wear. Ordinarily, the approximate control capacity is mentioned in catalogs or similar data sheets, but this alone is not sufficient. With special contact circuits, for the individual case, the maker either estimates from the past experience or makes test on each occasion. Also, in catalogs and similar data sheets, the control capacity that is mentioned is limited to resistive load, but there is a broad meaning indicated for that class of relay, and ordinarily it is proper to think of current capacity as that for 125V AC circuits. Minimum applicable loads are given in the catalog; however, these are only provided as a guide to the lower limit that the relay is able to switch and are not guaranteed values. The level of reliability of these values depends on switching frequency, ambient conditions, change in the desired contact resistance, and the absolute value. Please use relays with AgPd contacts when minute analog load control or contact resistance no higher than 100 mΩ is desired (for measurement and wireless applications, etc.). [Current] The current at both the closing and opening time of the contact circuit exerts important influence. For example, when the load is either a motor or a lamp, to the extent of the inrush current at the time of closing the circuit, wear of the contacts, and the amount of contact transfer increase, and contact welding and contact transfer make contact separation impossible. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines 2. Characteristics of Common Contact Materials Characteristics of contact materials are given below. Refer to them when selecting a relay. Ag (silver) Contact Material AgCd (silver-cadmium) Exhibits the conductivity and low contact resistance of silver as well as excellent resistance to welding. Like silver, it easily develops a sulfide film in a sulfide atmosphere. AgW (silver-tungsten) Hardness and melting point are high, arc resistance is excellent, and it is highly resistant to material transfer. However, high contact pressure is required. Furthermore, contact resistance is relatively high and resistance to corrosion is poor. Also, there are constraints on processing and mounting to contact springs. AgNi (silver-nickel) AgPd (silver-palladium) Rh plating (rhodium) Surface Finish Electrical conductivity and thermal conductivity are the highest of all metals. Exhibits low contact resistance, is inexpensive and widely used. A disadvantage is it easily develops a sulfide film in a sulfide atmosphere. Care is required at low voltage and low current levels. Au clad (gold clad) Au plating (gold plating) Equals the electrical conductivity of silver. Excellent arc resistance. At standard temperature, good corrosion resistance and good sulfidation resistance. However, in dry circuits, organic gases adhere and it easily develops a polymer. Gold clad is used to prevent polymer buildup. Expensive. Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an organic gas atmosphere, care is required as polymers may develop. Therefore, it is used in hermetic seal relays (reed relays, etc.) . Expensive. Au with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are uniform thickness and the nonexistence of pinholes. Greatly effective especially for low level loads under relatively adverse atmospheres. Often difficult to implement clad contacts in existing relays due to design and installation. Similar effect to Au cladding. Depending on the plating process used, supervision is important as there is the possibility of pinholes and cracks. Relatively easy to implement gold plating in existing relays. Au flash plating Purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a (gold thin-film plating) certain degree of contact stability can be obtained even when switching loads. 3. Contact Protection • Counter EMF When switching inductive loads with a DC relay such as relay sequence circuits, DC motors, DC clutches, and DC solenoids, it is always important to absorb surges (e.g. with a diode) to protect the contacts. When these inductive loads are switched off, a counter emf of several hundred to several thousand volts develops which can severely damage contacts and greatly shorten life. If the current in these loads is relatively small at around 1A or less, the counter emf will cause the ignition of a glow or arc discharge. The discharge decomposes organic matter contained in the air and causes black deposits (oxides, carbides) to develop on the contacts. This may result in contact failure. • Material Transfer Phenomenon Material transfer of contacts occurs when one contact melts or boils and the contact material transfers to the other contact. As the number of switching operations increases, uneven contact surfaces develop such as those shown in Fig. 14. After a while, the uneven contacts lock as if they were welded together. This often occurs in circuits where sparks are produced at the moment the contacts “make” such as when the DC current is large for DC inductive or capacitive loads or when the inrush current is large (several amperes or several tens of amperes). + E – ON OFF Peak voltage E 0 meter – Several hundred + to several e R thousand volts – di e = –L dt + (a) (b) Generally, the critical dielectric breakdown voltage at standard temperature and pressure in air is about 200 to 300 volts. Therefore, if the counter emf exceeds this, discharge occurs at the contacts to dissipate the energy (1/2Li2) stored in the coil. For this reason, it is desirable to absorb the counter emf so that it is 200V or less. Fig. 13 In Fig. 13 (a), an emf (e = –L di/dt) with a steep waveform is generated across the coil with the polarity shown in Fig. 13 (b) at the instant the inductive load is switched off. The counter emf passes through the power supply line and reaches both contacts. Contact protection circuits and contact materials resistant to material transfer such as AgSnO, AgW or AgCu are used as countermeasures. Generally, a concave formation appears on the cathode and a convex formation appears on the anode. For DC capacitive loads (several amperes to several tens of amperes), it is always necessary to conduct actual confirmation tests. Fig. 14 Meterial transfer of contacts All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines • Contact Protection Circuit Use of contact protective devices or protection circuits can suppress the counter emf to a low level. However, note that incorrect use will result in an adverse effect. Typical contact protection circuits are given in the table below. (G: Good NG: No Good) Application AC DC Circuit r * G G G Contact r c Inductive load NG G NG G Effective when the release time in the diode circuit is too long. G Using the stable voltage characteristics of the varistor, this circuit prevents excessively high voltages from being applied across the contacts. This circuit also slightly delays the release time. Effective when connected to both contacts if the power supply voltage is 24 or 48V and the voltage across the load is 100 to 200V. Inductive load Use a diode with a reverse breakdown voltage at least 10 times the circuit voltage and a forward current at least as large as the load current. In electronic circuits where the circuit voltages are not so high, a diode can be used with a reverse breakdown voltage of about 2 to 3 times the power supply voltage. Use a zener diode with a zener voltage about the same as the power supply voltage. G • Avoid using the protection circuits shown in the figures below. Although DC inductive loads are usually more difficult to switch than resistive loads, use of the proper protection circuit will raise the characteristics to that for resistive loads. (Fig. 15) • Mounting the Protective Device In the actual circuit, it is necessary to locate the protective device (diode, resistor, capacitor, varistor, etc.) in the immediate vicinity of the load or contact. If located too far away, the effectiveness of the protective device may diminish. As a guide, the distance should be within 50cm. • Abnormal Corrosion during High Frequency Switching of DC Loads (spark generation) If, for example, a DC valve or clutch is switched at a high frequency, blue-green rust may develop. This occurs from the reaction of nitrogen and oxygen in the air when sparks (arc discharge) are generated during switching. Fig. 15 — Contact Contact No good Power C supply Although extremely effective in arc suppression as the contacts open, the contacts are susceptible to welding since energy is stored in C when the contacts open and discharge current flows from C when the contacts close. • Type of Load and Inrush Current The type of load and its inrush current characteristics, together with the switching frequency, are important factors which cause contact welding. Particularly for loads with inrush currents, measure the steady state and inrush current. Then select a relay which provides an ample margin of safety. The table on the right shows the relationship between typical loads and their inrush currents. Also, verify the actual polarity used since, depending on the relay, electrical life is affected by the polarity of COM and NO. No good Power supply C Load Varistor Inductive load Contact Varistor circuit As a guide in selecting r and c, r: 0.5 to 1Ω per 1V contact voltage c: 0.5 to 1µF per 1A contact current Values vary depending on the properties of the load and variations in relay characteristics. Capacitor c acts to suppress the discharge the moment the contacts open. Resistor r acts to If the load is a relay or solenoid, the release time limit the current when the power is turned on lengthens. Effective when connected to both the next time. Test to confirm. Use a capacitor contacts if the power supply voltage is 24 or 48V with a breakdown voltage of 200 to 300V. Use and the voltage across the load is 100 to 200V. AC type capacitors (non-polarized) for AC circuits. Contact Inductive load Diode and zener diode circuit Diode If the load is a timer, leakage current flows through the CR circuit causing faulty operation. * If used with AC voltage, be sure the impedance of the load is sufficiently smaller than that of the CR circuit The diode connected in parallel causes the energy stored in the coil to flow to the coil in the form of current and dissipates it as joule heat at the resistance component of the inductive load. This circuit further delays the release time compared to the CR circuit. (2 to 5 times the release time listed in the catalog) Contact Diode circuit Devices Selection Load CR circuit c Inductive load Contact Features/Others Although extremely effective in arc suppression as the contacts open, the contacts are susceptible to welding since charging current flows to C when the contacts close. Type of load Resistive load Solenoid load Motor load Incandescent lamp load Mercury lamp load Sodium vapor lamp load Capacitive load Transformer load All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Inrush current Steady state current 10 to 20 times the steady state current 5 to 10 times the steady state current 10 to 15 times the steady state current Approx. 3 times the steady state current 1 to 3 times the steady state current 20 to 40 times the steady state current 5 to 15 times the steady state current General Application Guidelines Load Inrush Current Wave and Time (1) Incandescent Lamp Load (2) Mercury Lamp Load i/io ] 3 times (3) Fluorescent Lamp Load i/io ] 5 to 10 times L Contacts i i io i C io io (for high power factor type) 10 seconds or less 3 to 5 minutes The discharge tube, transformer, choke coil, capacitor, etc., are combined in common discharge lamp circuits. Note that the inrush current may be 20 to 40 times, especially if the power supply impedance is low in the high power factor type. Incandescent lamp Approx. 1/3 second Inrush current/rated current =i/io = 10 to 15 times (4) Motor Load i/io ] 5 to 10 times (5) Solenoid Load i/io ] 10 to 20 times (6) Electromagnetic Contact Load (7) Capacitive Load i/io ] 3 to 10 times i/io ] 20 to 40 times io i i io i io i 0.2 to 0.5 second • Conditions become more harsh if plugging or inching is performed since state transitions are repeated. • When using a relay to control a DC motor and brake, the on time surge current, normal current and off time brake current differ depending on whether the load to the motor is free or locked. In particular, with non-polarized relays, when using from b contact of from contact for the DC motor brake, mechanical life might be affected by the brake current. Therefore, please verify current at the actual load. 0.07 to 0.1 second Note that since inductance is great, the arc lasts longer when power is cut. The contact may become easily worn. • When Using Long Wires If long wires (100 to 300m) are to be used in a relay contact circuit, inrush current may become a problem due to the stray capacitance existing between wires. Add a resistor (approx. 10 to 50Ω) in series with the contacts. (Fig. 16) Equivalent circuit 1 to 2 cycles (1/60 to 1/30 seconds) 1/2 to 2 cycles (1/120 to 1/30 seconds) • Electrical life at high temperatures Verify at the actual use condition since electrical life may be affected by use at high temperatures. + Contacts Added resistor Wire 10 to 50Ω (100 to 300m) io Stray capacitance of wire Fig. 16 • Phase Synchronization in Switching AC Loads If switching of the relay contacts is synchronized with the phase of the AC power, reduced electrical life, welded contacts, or a locking phenomenon Vin (incomplete release) due to contact material transfer may occur. Therefore, check the relay while it is operating in the actual system. However, if problems develop, control the relay using an Fig. 17 appropriate phase. (Fig. 17) Ry Load Load voltage Load voltage Vin All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines 4. Cautions on Use Related to Contacts • Connection of load and contacts Connect the load to one side of the power supply as shown in Fig. 18 (a). Connect the contacts to the other side. This prevents high voltages from developing between contacts. If contacts are connected to both side of the power supply as shown in Fig. 18 (b), there is a risk of shorting the power supply when relatively close contacts short. Ry E E (a) Ry (b) Ry Ry (a) Good example (b) Bad example Home AC generator R1 R R2 N.C. Push-botton switch N.O. COM M Load R1 Load • Dummy Resistor Since voltage levels at the contacts used in low current circuits (dry circuits) are low, poor conduction is often the result. One method to increase reliability is to add a dummy resistor in parallel with the load to intentionally raise the load current reaching the contacts. • Avoid Circuits Where Shorts Occur Between Form A and B Contacts (Fig. 19) 1) The clearance between form A and B contacts in compact control components is small. The occurrence of shorts due to arcing must be assumed. 2) Even if the three N.C., and COM contacts are connected so that they short, a circuit must never be designed to allow the possibility of burning or generating an overcurrent. 3) A forward and reverse motor rotation circuit using switching of form A and B contacts must never be designed. Commercial AC power Fig. 18 R Relay coil R2 1) R1, R2 : Contacts for R R : Double pole relay 2) 3) R1, R2 : Contacts for R R : Double pole relay Fig. 19 • Shorts Between Different Electrodes Although there is a tendency to select miniature control components because of the trend toward miniaturizing electrical control units, care must be taken when selecting the type of relay in circuits where different voltages are applied between electrodes in a multi-pole relay, especially when switching two different power supply circuits. This is not a problem that can be determined from sequence circuit diagrams. The construction of the control component itself must be examined and sufficient margin of safety must be provided especially in creepage between electrodes, space distance, presence of barrier, etc. LATCHING RELAYS • Latching relays are shipped from the factory in the reset state. A shock to the relay during shipping or installation may cause it to change to the set state. Therefore, it is recommended that the relay be used in a circuit which initializes the relay to the required state (set or reset) whenever the power is turned on. • Avoid impressing voltages to the set coil and reset coil at the same time. • Connect a diode as shown since latching may be compromised when the relay is used in the following circuits. If set coils or reset coils are to be connected together in parallel, connect a diode in series to each coil. Fig. 20 (a), Fig. 20 (b) Also, if the set coil of a relay and the reset coil of another relay are connected in parallel, connect a diode to the coils in series. Fig. 20 (c) If the set coil or reset coil is to be connected in parallel with an inductive load (e.g. another electromagnetic relay coil, motor, transformer, etc.), connect a diode to the set coil or reset coil in series. Fig. 20 (d) (a) Parallel connection of set coils (b) Parallel connection of set coils (+) (+) S1 S2 S3 Reset coil S1 (–) Diode connection Diode connection Diode connection (c) Parallel connection of set coils and reset coils S1 S2 Reset coil Diode connection (d) Circuit with inductive load in parallel with the set coil or reset coil (+) (+) Set coil Reset coil Set coil Set coil (–) S3 Reset coil Reset coil Set coil Set coil S2 S3 S Reset coil AC or DC Set coil Set or reset coil Motor M (–) (–) Diode connection Diode connection Fig. 20 All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Diode connection Common relay coil General Application Guidelines Use a diode having an ample margin of safety for repeated DC reverse voltage and peak reverse voltage applications and having an average rectified current greater than or equal to the coil current. • Avoid applications in which conditions include frequent surges to the power supply. • Avoid using the following circuit since self-excitation at the contacts will inhibit the normal keep state. (Fig. 21) RLb • Four-Terminal Latching Relay In the 2 coil latching type circuit in Fig. 22, one terminal at one end of the set coil and one terminal at one end of the reset coil are connected in common and voltages of the same polarity are applied to the other side for the set and reset operations. In this type of circuit, short 2 terminals of the relay as noted in the next table. This helps to keep the insulation high between the two winding. RLa RL Load Set switch Set coil RL : Latching relay RLa : Form A contacts of RL RLb : Form B contacts of RL Reset coil Relay Type 1c DS 2c 4c Flat NC Slim ST SP DE JH Terminal Nos. — 15 & 16 * 5&6 3&4 * 2&4 1&2 6&8 Notes: 1. *DS4c and ST relays are constructed so that the set coil and reset coil are separated for high insulation resistance. 2. DSP, TQ, TQ-SMD, TN, TX, and SEB relays are not applicable due to polarity. Reset switch Bad example Fig. 21 Fig. 22 • Two Coil Latch Induction Voltage Each coil in a 2-coil latch relay is wound with a set coil and a reset coil on the same iron cores. Accordingly, induction voltage is generated on the reverse side coil when voltage is applied and shut off to each coil. Although the amount of induction voltage is about the same as the rated relay voltage, you must be careful of the reverse bias voltage when driving transistors. HANDLING CAUTIONS FOR TUBE PACKAGING Some types of relays are supplied in tube packaging. If you remove any relays from the tube packaging, be sure to slide the stop plug at one end to hold the remaining relays firmly together so they would not move in the tube. Failing to do this may lead to the appearance and/or performance being damaged. Slide in the plug. Stop plug AMBIENT ENVIRONMENT 1. Ambient Temperature and Atmosphere Be sure the ambient temperature at the installation does not exceed the value listed in the catalog. Furthermore, environmentally sealed types (plastic sealed type, metallic hermetic seal type) should be considered for applications in an atmosphere with dust, sulfur gases (SO2, H2 S), or organic gases. 2. Silicon Atmosphere Please use something other than silicon based materials (silicon rubber, silicon oil, silicon-based coatings, and silicon bulking agents, etc.) in the vicinity of the relay since their use will generate volatile gas. When contacts are switched in such an environment, silicon may adhere to the contacts and lead to contact failure (in plastic seal types, too). 3. NOx Generation When a plastic sealed type relay is used in an atmosphere high in humidity to switch a load which easily produces an arc, the NOx created by the arc and the water absorbed from outside the relay combine to produce nitric acid. This corrodes the internal metal parts and adversely affects operation. Avoid use at an ambient humidity of 85%RH or higher (at 20°C 68°F). If use at high humidity is unavoidable, consult us. 4. Vibration and Shock If a relay and magnetic switch are mounted next to each other on a single plate, the relay contacts may separate momentarily from the shock produced when the magnetic switch is operated and result in faulty operation. Countermeasures include mounting them on separate plates, using a rubber sheet to absorb the shock, and changing the direction of the shock to a perpendicular angle. 5. Influence of External Magnetic Fields Permanent magnets are used in reed relays and polarized relays (including NR relays), and their movable parts are constructed of ferrous materials. For this reason, when a magnet or permanent magnet in any other large relay, transformer, or speaker is located nearby, the relay characteristics may change and faulty operations may result. The influence depends on the strength of the magnetic field and it should be checked at the installation. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines 6. Usage, storage, and transport conditions 1) During usage, storage, or transportation, avoid locations subject to direct sunlight and maintain normal temperature, humidity, and pressure conditions. The allowable specifications for environments suitable for usage, storage, and transportation are given below. • Temperature: The allowable temperature range differs for each relay, so refer to the relay’s individual specifications. In addition, when transporting or storing relays while they are tube packaged, there are cases when the temperature may differ from the allowable range. In this situation, be sure to consult the individual specifications. • Humidity: 5 to 85 % R.H. TX(-SMD) / TX-D(-SMD) / TQ-SMD ;;;;;;; ; ; ;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;; ;;;;;;;;;;;; ;;;;;;;;;;;; ;;;;;;;;;;;; ;;;;;;;;;;;; ;;;;;;;;;;;; Humidity, %R.H. 85 Tolerance range (Avoid freezing when (Avoid used at temperatures condensation when lower than 0°C 32°F) used at temperatures higher than 0°C 32°F) 5 –40 –40 0 +32 Temperature, °C °F +85 +185 • Pressure: 86 to 106 kPa The humidity range varies with the temperature. Use within the range indicated in the graph above. 2) Condensation Condensation forms when there is a sudden change in temperature under high temperature, high humidity conditions. Condensation will cause deterioration of the relay insulation. 3) Freezing Condensation or other moisture may freeze on the relay when the temperatures is lower than 0°C 32°F. This causes problems such as sticking of movable parts or operational time lags. 4) Low temperature, low humidity environments The plastic becomes brittle if the relay is exposed to a low temperature, low humidity environment for long periods of time. • Be aware that plastic may become brittle in low-temperature, low-humidity environments. When stored in high-temperature, highhumidity environments, and in environments with organic or sulfide gases for long periods of time (including during transport), sulfide or oxide membrane will form on the surfaces of the contacts, which may lead to contact instability or malfunction, as well as functional disorder. Please verify the environment for storing and transporting. • Packaging should be designed to reduce, as much as possible, the influence of humidity, organic gas and sulfide gas when packaging. • Since the SMD type is sensitive to humidity it is packaged with tightly sealed anti-humidity packaging. However, when storing, please be careful of the following. (1) Please use promptly once the antihumidity pack is opened. (As a guide, use within one week.) (2) When storing for a long period after opening the anti-humidity pack, storage in a humidity-controlled desicator or in antihumidity packaging with an anti-humidity bag to which silica gel has been added, is recommended. (As a guide, storage can be for three months.) 7. Vibration, Impact and Pressure when Shipping When shipping, if strong vibration, impact or heavy weight is applied to a device in which a relay is installed, functional damage may occur. Therefore, please package in a way, using shock absorbing material, etc., so that the allowable range for vibration and impact is not exceeded. ENVIRONMENTALLY SEALED TYPE RELAYS Sealed type relays are available. They are effective when problems arise during PC board mounting (e.g. automatic soldering and cleaning). They also, of course, feature excellent corrosion resistance. Note the cautions below regarding the features and use of environmentally sealed type relays to avoid problems when using them in applications. 1. Operating Environment Plastic sealed type relays are not suited for use in environments that especially require air tightness. Although there is no problem if they are used at sea level, avoid atmospheric pressures beyond 96±10kPa. Also avoid using them in an atmosphere containing flammable or explosive gases. Use the metallic hermetic seal types for these applications. PROCESSING CONSIDERATIONS 1. Handling State of the art relays are precision mechanical devices and as such are sensitive to abusive handling practices. Every attempt is made during their manufacture to preclude any anomalies. Relays are packed in a variety of ways to best protect them during shipment and subsequent handling. These include the use of “Egg Crate” type inserts which support the relay and prevent damage to the terminals, foam trays which prevent shock damage, and tubes similar to those used by semiconductor manufacturers for machine dispensing and assembly. During incoming inspection and subsequent customer handling operations, care should be taken so as not to degrade the device which has been supplied in prime condition. Some key areas of concern: (1) Terminals should not be handled in order to prevent contamination of the surface finish. This could lead to solderability problems. (2) Terminal layout and P.C. board hole pattern should match. Any misalignment caused by mis-registered P.C. board holes can lead to severe stress on the relay, compromising performance and reliability (seal integrity). (3) The storage temperature specification should be observed. (4) Relays should be stored and handled in a suitably clean area. 2. Fluxing Depending upon the type of relay involved, fluxing procedures should be researched carefully. An unsealed relay is prone to internal flux contamination which can compromise contact performance, and ideally should be hand soldered. “Flux-resistant” relays are available which will prevent flux migration through the terminal-header interface. These and “sealed” relays are compatible with mist foam or spray fluxing operations, however “Flux-resistant” types are not totally sealed which precludes washing operations, and makes a non-active flux almost a necessity. Pre-heating the board assembly prior to soldering “Flux-resistant” types will dry the flux and further help to prevent flux being driven into the relay during the soldering operation. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines 3. Soldering As with fluxing, automated soldering processes can, unless controlled carefully, compromise the performance of unsealed relays. Flux-resistant and sealed types are compatible with mist dip or wave soldering procedures. Some state-of-the-art relays are suitable for various reflow processes, such as I.R. or vapor phase maximum soldering temperatures and times will vary from relay type to relay type, and should not be exceeded. The use of an I.R. reflow process with a relay not specifically designed to withstand the process, will in all probability degrade the relay and cause performance problems. A safe practice would be to review the thermal profile of the process on a case by case basis with your local Matsushita office. 4. Cleaning Any cleaning process which involves potential contamination of an unsealed relay should be avoided. Sealed devices can be immersion cleaned in a suitable solvent (see solvent compatibility chart). Cleaning in a ultrasonic bath should also be avoided. A harmonic of the bath frequency may be induced in the contacts causing friction welding and subsequent contact sticking. Relays with a removable “vent” tab should be vented after cooling to room temperature following cleaning and drying. MOUNTING CONSIDERATIONS • Top View and Bottom View Relays used for PC boards, especially the flat type relays, have their top or bottom surface indicated in the terminal wiring diagrams. Relay with terminals viewed from the bottom (terminals cannot be seen from the top) Relay with terminals viewed from the top (all terminals can be seen from the top) Note during PC board pattern design (NL, NC) • Mounting Direction Mounting direction is important for optimum relay characteristics. • Shock Resistance It is ideal to mount the relay so that the movement of the contacts and movable parts is perpendicular to the direction of vibration or shock. Especially note that the vibration and shock resistance of Form B contacts while the coil is not excited is greatly affected by the mounting direction of the relay. • Contact Reliability Mounting the relay so the surfaces of its contacts (fixed contacts or movable contacts) are vertical prevents dirt and dust as well as scattered contact material (produced due to large loads from which arcs are generated) and powdered metal from adhering to them. Furthermore, it is not desirable to switch both a large load and a low level load with a single relay. The scattered contact material produced when switching the large load adheres to the contacts when switching the low level load and may cause contact failure. Therefore, avoid mounting the relay with its low level load contacts located below the large load contacts. • Adjacent Mounting When many relays are mounted close together, abnormally high temperatures may result from the combined heat generated. Mount relays with sufficient spacing between them to prevent heat buildup. This also applies when a large number of boards mounted with relays are installed as in a card rack. Be sure the ambient temperature of the relay does not exceed the value listed in the catalog. • Influence of Adjacent Mounting of Polarized Relays When polarized relays are mounted close together, their characteristics change. Since the affect of adjacent mounting differs according to the type of relay, refer to the data for the particular type. • Panel Mounting -Do not remove the panel. It has a special function. (It will not come off under normal handling.) -When installing please use washers to prevent damage and deformation. Please keep the tightening torque to within 0.49 to 68.6 N (5 to 7 kgf). Also, please use a spring washer to prevent it from coming loose. • Tab Terminals As a guide, use a quick connect mounting pressure of 40 to 70N {4 to 7 kgf} for relays with tab terminals. METHOD OF MOUNTING • The direction of mounting is not specifically designated, but to the extent possible, the direction of contact movement should be such that vibration and shock will not be applied. When a terminal socket is used • After drilling the mounting holes, the terminal socket should be mounted making certain the mounting screws are not loose. DIN standard sockets are available for one-touch mounting on DIN rail of 35mm 1.378 inch width. When reversible terminal sockets are used • The reversible terminal sockets (HC, HL socket) are for one-touch mounting. (A panel thickness of 1 to 2mm .039 to .079 inch should be used.) (Fig. 23) Fig. 24 Fig. 23 • The socket should be pushed through the opening in the mounting panel until the projections on the side of the mounting bracket extend out over the back surface. (Fig. 24) • When all four of the projections are visible from the back side of the mounting panel, the mounting is completed and the socket is fastened. • To remove the socket, the projections on the side of the mounting bracket should be pushed inward and at the same time the body of the socket should be pushed lightly from the back side. The socket can then be removed from the panel. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines REGARDING CONNECTION OF LEAD WIRES • When making the connections, depending upon the size of load, the wire cross-section should be at least as large as the values shown in the table below. Permissible current 2 3 5 7.5 12.5 15 20 30 Cross-section (mm2) 0.2 0.3 0.5 0.75 1.25 2 2 3.5 • When the terminal board uses screw fastening connections, either pressure terminals or other means should be used to make secure fastening of the wire. To prevent damage and deformity, please use a torque within the following range when tightening the push screw block of the terminal block. M4.5 screw: 1.47 to 1.666 N·m (15 to 17 kgf·cm) M4 screw: 1.176 to 1.37 N·m (12 to 14 kgf·cm) M3.5 screw: 0.784 to 0.98 N·m (8 to 10 kgf·cm) M3 screw: 0.49 to 0.69 N·m (5 to 7 kgf·cm) All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines CAUTIONS FOR USE–Check List Check Item 1. Is the correct rated voltage applied? 2. Is the applied coil voltage within the allowable continuous voltage limit? 3. Is the ripple in the coil voltage within the allowable level? 4. For voltage applied to a polarized coil, is polarity observed? Coil Drive Input 5. When hot start is required, is the increase in coil resistance resulting from coil temperature rise taken into account in setting coil voltage? 6. Is the coil voltage free from momentary drop caused by load current? (Pay special attention for self-holding relays.) 7. Is supply voltage fluctuation taken into account when setting the rated coil voltage? 8. The relay status may become unstable if the coil voltage (current) is gradually increased or decreased. Was the relay tested in a real circuit or with a real load? 9. When driving with transistors, did you consider voltage drops? 1. Is the load rated within the contact ratings? 2. Does the load exceed the contacts’ minimum switching capacity? 3. Special attention is required for contact welding when the load is a lamp, motor, solenoid, or electromagnetic contractor. 4. Was the relay tested with a real load? A DC load may cause contact lock-up due to large contact transfer. Was the relay tested with a real load? 5. For an inductive load, is a surge absorber used across the contacts? Load (Relay contacts) 6. When an inductive load causes heavy arc discharge across the relay contacts, the contacts may be corroded by chemical reaction with nitrogen in the atmosphere. Was the relay tested with a real load? 7. Platinum contacts may generate brown powder due to a catalyzer effect or vibration energy. Was the relay tested with a real load? 8. Is the contact switching frequency below the specification? 9. When there are more than two sets of contacts (2T) in a relay, metallic powder shed from one set of contacts may cause a contact failure on the other set (particularly for light loads). Was the relay tested in a real circuit? 10. A delay capacitor used across relay contacts may cause contact welding. Was the relay tested with a real load? 11. For an AC relay, a large contact bounce may cause contact welding. Was the relay tested in a real circuit or with a real load? 12. A high voltage may be induced at transformer load. Was the relay tested with a real load? 1. Does circuit design take into account electrolytic corrosion of the coil? 2. Are transistors and other circuit components protected rom counter electromotive force that develops across the relay coil? 3. Is the circuit designed so the relay coil is left deenergized while the relay is inactive for long period of time? 4. Is the relay operated within the ratings approved by the relevant international standard (if compliance is required)? 5. Is the circuit protected from malfunction when the relay’s activation and/or deactivation time varies considerably? 6. Is the circuit protected from malfunctions that might result from relay contact bounce? 7. Is the circuit protected from malfunction when a high-sensitivity self-holding relay, such as NR type, is to be used? Circuit Design 8. When there are two or more sets of contacts (2T) in a relay, arc discharges from load switching may cause short circuits across the two or more sets of contacts. Is the circuit designed to suppress such arc discharges? 9. Item 8 above also requires special attention when loads are supplied from separate power sources. 10. Does the post-installation insulation distance comply with the requirement of the relevant international standard or the Electrical Appliance and Material Control Law? 11. Is the circuit protected from malfunction when the relay is to be driven by transistors? 12. When the SCR is used for on/off control, the relay activation tends to synchronize with the line frequency, resulting in an extremely shortened life. Was the relay tested in a real circuit or with a real load? 13. Does the PC board design take into account use of on-board relay? 14. RF signals may leak across relay’s open contacts. Check for adequate contact isolation and use RF relays as needed. All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. General Application Guidelines Check Item 1. Is the ambient temperature in the allowable operating temperature range? 2. Is relative humidity below 85 percent? 3. Is the operating atmosphere free from organic and sulfide gases? 4. Is the operating atmosphere free from silicon gas? Depending on the load type, silicon gas may cause a black substance to from on the contacts, leading to contact failure. Operating Environment 5. Is the operating atmosphere free from excessive airborne dust? 6. Is the relay protected from oil and water splashes? 7. Is the relay protected from vibration and impact which may cause poor contact with the socket? 8. Is ambient vibration and impact below the level allowable for the relay? 9. Is the relay free from mechanical resonance after it is installed in position? 10. Is insulation coating applied to the relay along with the PC board? Depending on the load type, a black substance may form to cause contact failure. 1. Is the relay protected from solder chips and flux when it is manually soldered? 2. Are preparations for flux application and automatic soldering complete? 3. Is the PC board cleaning process designed to minimize adverse affects to the relays? 4. Are adequate separations provided between polarized or reed relays to prevent magnetic coupling? 5. Are the relay terminals free from stress in the socket? 6. Polarized relay’s characteristics may be affected by strong external magnetic field. Are the relays installed away from such fields? Installation and Connection 7. If very long leads (100 to 300 meters) are used to connect the load, the stray capacity existing across the leads may cause a surge current. Was the relay tested with a real load? 8. Unless otherwise specified, all relay terminals should be soldered at 250°C 482°F within 5 sec. or at 350°C 662°F within 3 sec. 9. A badly warped PC board can cause stress to the relay terminals which may lead to degraded relay characteristics. 10. Glass shot should not be used to clean the PC board of solder flux. This may cause relay malfunction due to glass powder becoming lodged in the relay’s internal structure. 11. Relays should always be used with their plastic shields installed, or degraded relay performance may result. 12. Do not cut away any relay terminal as the stress may cause degraded relay performance. 1. Is the relay subject to freezing or condensation (especially when shipping)? 2. Is the temperature in the allowable temperature range? 3. Is the humidity in the allowable humidity range? Storage and Transport 4. Is the storing atmosphere free from organic and sulfide gases? 5. Is the storing atmosphere free from excessive airborne dust? 6. Is the relay protected from oil and water splashes? 7. Is the relay subject to the application of heavy weight? 8. When shipping does vibration and impact exceed the allowable range? All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Reliability • What is Reliability? 1. Reliability in a Narrow Sense of the Term In the industrial world, reliability is an index of how long a particular product serves without failure. 2. Reliability in a Board Sense of the Term Every product has a finite service lifetime. This means that no product can continue normal service infinitely. When a product has broken down, the user may throw it away or repair it. The reliability of repairable products is recognized as “reliability in a broad sense of the term”. For repairable products, their serviceability or maintainability is another problem. In addition, reliability of product design is becoming a serious concern for the manufacturing industry. In short, reliability has three senses: i.e. reliability of the product itself, serviceability of the product, and reliability of product design. • Reliability Measures The following list contains some of the most popular reliability measures: Reliability measure Reliability (broad sense) f(t) T Time (a) R(T) MTTF (b) MTTF 10% Product reliability at the user’s site is called “reliability of use”, which consists mainly of reliability in the broad sense. In the relay industry, reliability of use has a significance in aspects of servicing. 1. Reliability (narrow sense), durability Long life time: MTTF, B10, R(T), Low failure rate: Lamda (λ), MTBF 2. Maintainability MTTR Preventive maintenance, predicted maintenance 3. Design reliability Human factor, redundancy, fool-proof, fail-safe 1. Degree of Reliability Degree of reliability represents percentage ratio of reliability. For example, if none of 10 light bulbs has failed for 100 hours, the degree of reliability defined in, 100 hours of time is 10/10 = 100%. If only three bulbs remained alive, the degree of reliability is 3/10 = 30%. The JIS Z8115 standard defines the degree of reliability as follows: The probability at which a system, equipment, or part provides the specified functions over the intended duration under the specified conditions. 2. MTBF MTBF is an acronym of mean time between failures. It indicates the mean time period in which a system, equipment, or part operates normally between two incidences of repair. MTBF only applies to repairable products. MTBF tells how long a product can be used without the need for repair. Sometimes MTBF is used to represent the service lifetime before failure. 3. MTTF MTTF is an acronym of mean time to failure. It indicates the mean time period until a product becomes faulty MTTF normally applies to unrepairable products such as parts and materials. The relay is one of such objective of MTTF. ;; ;;;; ;;; Degree of reliability R(T) MTBF MTTF Failure rate λ Safe life B10 Sample representation 99.9% 100 hours 100 hours 20 fit, 1%/hour 50 hours 3. Intrinsic Reliability and Reliability of Use Reliability is “built” into products. This is referred to as intrinsic reliability which consists mainly of reliability in the narrow sense. Availability 4. Failure Rate Failure rate includes mean failure rate and momentary failure rate. Mean failure rate is defined as follows: Mean failure rate = Total failure count/total operating hours In general, failure rate refers to momentary failure rate. This represents the probability at which a system, equipment, or part, which has continued normal operation to a certain point of time, becomes faulty in the subsequent specified time period. Failure rate is often represented in the unit of percent/hours. For parts with low failure rates, “failure unit (Fit) = 109 /hour” is often used instead of failure rate. Percent/count is normally used for relays. 5. Safe Life Safe life is an inverse of degree of reliability. It is given as value B which makes the following equation true: 1 – R(B) = t % In general, “B[1 – R(B)] = 10%” is more often used. In some cases this represents a more practical value of reliability than MTTF. B10 (c) Safe life All Rights Reserved © COPYRIGHT Matsushita Electric Works, Ltd. Reliability Failure rate (I) Weibull distribution can be adopted to the actual failure rate distribution if the three variables above are estimated. ;;;; ;;; (III) Wear-out failure period In the final stage of the product’s service lifetime comes the wear-out failure period, in which the life of the product expires due to wear of fatigue. Preventive maintenance is effective for this type of failure. The timing of a relay’s wear-out failure can be predicted with a certain accuracy from the past record of uses. The use of a relay is intended only in the accidental failure period, and this period virtually represents the service lifetime of the relay. [3] Weibull Analysis Weibull analysis is often used for classifying a product’s failure patterns and to determine its lifetime. Weibull distribution is expressed by the following equation: m m –1 (χ–γ) f (x) = m α (χ–γ) e – α where m : Figure parameter α : Measurement parameter γ : Position prameter ( II ) ( III ) Failure rate • Failure [1] What is Failure? Failure is defined as a state of system, equipment, or component in which part of all of its functions are impaired or lost. [2] Bathtub Curve Product’s failure rate throughout its lifetime is depicted as a bathtub curve, as shown below. Failure rate is high at the beginning and end of its service lifetime. (I) Initial failure period The high failure rate in the initial failure period is derived from latent design errors, process errors, and many other causes. Initial failures are screened at manufacturer’s site through burn-in process. This process is called debugging, performing aging or screening. (II) Accidental failure period The initial failure period is followed by a long period with low, stable failure rate. In this period, called accidental failure period, failures occurs at random along the time axis. While zero accidental failure rate is desirable, this is actually not practical in the real world. m 63% α The Weibull probability chart is a simpler alternative of complex calculation formulas. The chart provides the following advantages: (1) The Weibull distribution has the closest proximity to the actual failure rate distribution. (2) The Weibull probability chart is easy to use. (3) Different types of failures can be identified on the chart. The following describes the correlation with the bathtub curve. The value of the parameter “m” represents the type of the failure. (1) When m < 1: Initial failures (2) When m = 1: Accidental failures (3) When m > 1: Wear-out failures m>1 m