CT-50/5

CT Series OPERATION The CT Current Transformers are of the inserted primary type with the secondary toroidally wound over a core of oriented electrical steel. The windings are carefully insulated. The entire transformer is then dipped in PVC insulation compound which insures maximum protection against moisture, acids, alkaline, oils and abrasive particles. The securely fastened 24” 14 AWG leads are identified to the extent that the secondary current leaving the CT through the white lead is in phase with the primary current when the primary conductor enters the CT from the side identified by the black dot. To prevent shock and transformer damage, it is important that the secondary leads always form a continuous circuit when the current is flowing in the primary. An External CT may be used to extend the range of the AC Current Monitors. Current Transformers DIMENSIONS (INCHES) • 600 Volt Insulation • 25 - 400 Hz Operation • 25/5 to 2500/5 Amperes • Optional Mounting Bracket (Add Suffix-B to part number) SPECIFICATIONS CT-25/5 CT-50/5 CT-100/5 CT-200/5 CT-500/5 CT-1000/5 CT-2500/5 25/5 50/5 100/5 200/5 500/5 1000/5 2500/5 2 V.A. 6.00% 2 V.A. 6.00% 2 V.A. 3.00% 2 V.A. 1.50% 2 V.A. .60% 2 V.A. .30% 5 V.A. .10% 1 2 3 3 3 4 5 3 lb. 5 oz. 1lb. 6 oz. 1lb. 4.5 oz. 15 oz. 1 lb. 1 oz. 3 lb. 3 lb. 4 oz. NOTES: GROUP SIZE 1 2 3 4 5 A B C I 1-1/4 1-1/4 1-1/4 1-7/8 3-3/8 3-3/4 3-7/8 3-1/2 4 6-1/2 2-3/4 1-1/4 1-1/4 1-1/4 1-11/16 5-1/4 4-1/2 4-1/2 4-1/2 7-7/8 II III IV 4 2-1/8 0.281 x 0.5 3-7/8 7/8 0.250 x 0.375 3-7/8 7/8 0.250 x 0.375 3-7/8 7/8 0.250 x 0.375 6-1/2 1-1/8 0.281 x .5 1. The current ratio in the table is the ratio of current in the primary/ secondary with one turn on the primary. The ratio can be increased by adding turns on the primary. 2. The transformers may be installed at some distance from the load. However, the interconnecting conductor resistance must not cause the VA rating of the transformer to be exceeded. CURRENT MONITORS MODEL RATIO CAPACITY ACCURACY GROUP WEIGHT 3. CTs should not be operated at twice the rated currents. For example, CT-25/5 should not operate above 50/10 amps. With current too high overheating will occur. WIRING Diversified Electronics 800.727.5646 atcdiversified.com 187 THREE PHASE CURRENT UNBALANCE Example: Balanced or matched currents on a three phase system are difficult to maintain because of the many varying factors involved such as, unequal single phase loading, poor connections and cabling and/or dirty or burnt starter contacts. Although these varying factors can be controlled to maintain as close as possible a balanced line, the unseen conditions such as overheated motor windings, burnt bearings, low voltage, high voltage and single phasing need to be constantly monitored to protect your valuable equipment. Measure the current on each leg. Assume A = 10 amps B = 12 amps C = 9 amps 2. Find Average 10 + 12 + 9 = 31 31 = 10.33 3 The CLB Series Three Phase Current Unbalance and Over Current Monitor (page 176) offers this protection. To determine the condition of your three phase line and to properly select the CLB Series percent unbalance setting a simple calculation formula is needed as follows: 1. (I max - I avg) x 100 I max I max = 12 I avg = 10.33 Apply formula 12 - 10.33 = 1.67 3. 1.67 = .139 x 100 = 13.9% unbalance 12 CURRENT MONITORS EXTERNAL CURRENT TRANSFORMERS The load or burden that can be connected to the secondary of the Current Transformer is usually specified in VA. The rated accuracy of the Current Transformer is guaranteed only when the sum of the VA ratings of all devices (ampmeters, wattmeters, current monitors, etc.) connected to the secondary windings does not exceed the specified VA rating. If the only load on the Current Transformer is a DE Current Monitor, its VA rating (approx. 0.15 VA) is small compared to the Current Transformer rating and can be neglected. This means that the resistance of the wiring can be 80 milliohms max. for the 2 VA units and 200 milliohms max for the 5 V A unit. Gauge Ohms per 1000' Milliohms per foot The interconnecting conductor resistance must also be considered, especially when the Transformer is installed at some distance from the Current Monitor or other load. AWG 14 2.5 2.5 AWG 16 4.0 4.0 For the wiring, the VA can be calculated using Ohm’s Law: AWG 18 6.4 6.4 VA = E x I = (I x R) x I = I2R AWG 20 10.0 10.0 Where I = 5 Amps and R is the DC resistance of the wire. Example: All of the standard DE Current Transformers have a rating of 2 VA except the 2500/5 version which has a 5 VA rating. For a 2 VA Current Transformer, the length of AWG 16 wire would be: From the above formula we can also calculate the maximum resistance that can be connected to the secondary of a Current Transformer: VA=I R, Hence R = VA I2 2 Example: VA = 2 VA = 5 188 Rmax = VA = 2 = 0.08 Ohms = 80 milliohms I2 (5)2 Rmax = VA = 5 = 0.2 Ohms = 200 milliohms I2 (5)2 Diversified Electronics 80 milliohms 4.0 milliohms/ft = 20' Because we are dealing with a pair of wires, the maximum distance from the Current Transformer to the Current Monitor can be only 10 ft. As we can see, it is important to keep the wire length to minimum, use heavy wire, and keep all connections clean and tight. 800.727.5646 atcdiversified.com ALTERNATING CONTROLLERS ATC-Diversified Electronics offers a wide variety of models for various staging requirements. The different models available are: Duplexors, Triplexors, Quadraplexors, Special Function, and Expandable Alternating Relays. The Alternating Relay is used in multiple load installations to assure equal run time on all loads. They also allow for the addition of more capacity in the event of excess load requirements. The Alternating Relay provides equal run time on two or more loads by alternating the sequence in which the loads are allowed to start up. In each case, the alternating action is initiated each time the control switch across designated terminal opens. The control switch may be a float, a thermostat, a pressure switch, or a timer contact. The ARM Series, Alternating Controllers, are used in multiple load installations to assure equal run time on all loads. They also allow for the addition of more capacity in the event of excess load requirements. The Alternating Controllers provide equal run time on two or more loads by alternating the sequence in which the loads are allowed to start up. All ARM models feature intrinsically safe inputs and logic that allows the outputs to operate even if one of the inputs fails to open or close. For example: if the off switch fails to close, the lead load will not energize until both the lead and the lag switches close. An inrush delay on all models reduces line sags by preventing multiple loads from energizing simultaneously. ARA, ARM Series ALTERNATING RELAYS ARM-XXX-ABEP ARA-XXX-AGE ARM-XXX-ACE ARA-120-AHE ARM-XXX-ACEP ARA-120-AJE ARM-XXX-ADE ARA-120-AME ARM-XXX-ADEP ARA-120-ANE ARM-XXX-AFE ARB-XXX-ABA ARM-XXX-AFEP ARB-XXX-ACA ARM-XXX-AGE ARB-XXX-ADA ARM-XXX-AGEP ARB-XXX-AEA ARM-XXX-AHE ARC-XXX-AAA ARM-XXX-AHEP ARD-XXX-AAA AUC-XXX-AAA PUMP & LEVEL CONTROLS ARA-XXX-AFE UL LISTED 913 ARM-XXX-ABE LEAD SELECT ARA-XXX-AEA OMIT ARM-XXX-AAEP OUTPUT LOGIC (FOSO) ARA-XXX-ADA 4 OUTPUT LOGIC (SOSO) ARM-XXX-AAE 3 SELECTABLE SEQUENCING ARA-XXX-ACA 2 AUTOMATIC ALTERNATING Model Number PANEL MOUNT ARA-XXX-ABA STYLE SURFACE MOUNT CSA CERTIFIED NUMBER OF LOADS SEQUENCED FEATURE MATRIX UL LISTED E UL/CANADIAN UL RECOGNIZED A FIELD SELECTABLE SEQUENCING 4 AUTOMATIC ALTERNATING 3 EXTERNAL CLOCKING 2 EXPANDABLE Model Number ENCLOSURE STYLE NUMBER OF LOADS SEQUENCED FEATURE MATRIX AUD-XXX-AAA Diversified Electronics 800.727.5646 atcdiversified.com 189