DMS Accessories www.murata-ps.com 5 Amp AC Current Transformers These commercial grade, UL & CSA recognized, donut style AC current-transformers GENERAL SPECIFICATIONS (ALL MODELS) (CTs) provide an isolated 0-5A output that can be used with Murata Power Solutions ACA5 Insulation Class 600V, 10kV BIL full wave (1) Series of digital ammeters. Installation is straightforward: simply pass the load-carrying Frequency Range 50-400Hz conductor through the 5A CTs primary window, and then route its secondarys leads through the ACA5-ammeters built-in, low-burden, toroid sensor. Supplied Secondary All models feature rugged, fully insulated construction, allowing continuous operation Max. Secondary Lead with primary voltages up to 600Vac, at line frequencies from 50 to 400Hz. Fourteen models Rated Accuracy are available to enable accurate measurements from 50A through 2000A. When combined with Murata Power Solutions ACA5 Series ammeters, secondary lead-extensions may be Burden See Table 1 used for those applications where the CT cannot be installed in the immediate vicinity of UL FIle No. the ammeter. CSA File No. TECHNICAL NOTES Weight IMPORTANT To ensure safe and reliable operation, Current Transformers and asso- (1) Basic Lightning Impulse Insulation Level (BIL): The ciated equipment must be installed and serviced by qualiefi d technical personnel. insulation strength referenced to the crest value of an Never open the CTs secondary connections while the primary is energized. Open impulse voltage-waveform which rises to a crest value in CT secondary wiring can generate potentially lethal voltages when the primary cir- 1.2 microseconds, then drops to the crest value in 50 microseconds. cuit is energized. Contact Murata Power Solutions if you have any doubts regarding the installation or operation of any of our ac-mains measurement instruments and accessories. 1. CT Precautions: In normal operation, a 5A current transformers secondary circuit oper- ates at a relatively low voltage due to its closed-loop, low burden congfi uration (essentially zero Ohms when used with Murata Power Solutions ACA5 series ammeters). However, any CT can generate potentially lethal voltages if its output current is suddenly interrupted. AC POWER SUPPLY For example, loose secondary connections can produce a condition referred to as induc- tive kick. Inductive kick can generate extremely high voltages across the open secondary ACA5-20PC-X-ACX connections. AB TB1 Therefore, all connections made to a CTs secondary leads must only be performed with TO AC LOAD L1 zero current flowing in the primary circuit. Never operate a CT with its secondary circuit open and current flowing in the primary. 5A CURRENT TRANSFORMER 2. CT Connections and Grounding: Some applications require connecting one of the CTs (see technical notes) 5A output terminals to earth/chassis ground. In the USA, consult the latest revision of the National Electrical Code for more information. 0-5A OUTPUT After all mechanical assembly is completed, pass the 5A secondary leads through the ACA5 ammeters built-in toroid, then connect the two leads together as shown in Figure 1. For this connection, and for connections involving lead extensions, pressure-style Figure 1. Typical Connections connectors (commonly called wire nuts) are acceptable as long as they are rated for the currents and voltages involved. 3. Installation: CTs must be installed in a manner that ensures no excessive stresses are applied to the primary conductor that passes through the CT or to the secondary circuit and its associated instruments. Use plastic tie-wraps and/or other suitable non-conductive restraining devices to secure the CT. For full details go to www.murata-ps.com/rohs www.murata-ps.com/support MPM DMS-CT.B05 Page 1 of 4DMS Accessories 5 Amp AC Current Transformers TECHNICAL NOTES 4. Reference Documentation: Prior to connecting CTs to any measure- burden column. Accuracy measurements are taken at 100% primary ment device (analog or digital), relay, or other apparatus, be sure to current, using a resistive burden and a nominal line frequency of 60Hz. thoroughly review the applicable devices technical documentation (for 7. Polarity: CTs are marked with H1 (primary) and X1 (secondary) example, Murata Power Solutions ACA5-20PC product data sheet). In polarity indicators. When a CTs only function is to measure amperes, particular, make sure the CTs ratings meet the requirements of your polarity markings can be disregarded. However, correct polarity is application. mandatory in applications in which the phase relationship between 5. Secondary Lead Extensions: When calculating the total burden two currents is involved (watt or watt-hour meters are two examples imposed on a CTs 5A output, Murata Power Solutions ACA5 digital of polarity sensitive applications). Refer to the respective instruments ammeters input impedance is negligible and can be assumed to be documentation for more information. zero Ohms. In many applications, the length of secondary wiring can 8. Thermal Rating Factor: The thermal rating factor denotes the amount be increased up to the value specified in Table 1 without adversely by which the primary current can be increased on a continuous affecting performance. basis over its rated value without exceeding the CTs maximum In order to achieve the specified accuracy, the maximum permissible temperature rise. burden must not exceed the value shown in Table 1. When used with The formula below can be used to calculate thermal rating factors at ACA5 ammeters, the total burden is the sum of the resistance of the temperatures above 30C. CTs 24 leads and any lead-extensions. Make sure all connections 2 (85 - NAT)(RF) are securely tightened and properly strain relieved. If terminal blocks NRF = are used for intermediary connections, refer to the manufacturers NAT torque recommendations. NRF = Rating Factor at New Ambient Temperature Table 1 lists general guidelines for adding lead extensions when RF = 30C Rating Factor using Murata Power Solutions ACA5-Series ammeters as the readout NAT = New Ambient Temperature device. The lengths in Table 1 assume the lead extensions are 16AWG. Stated dimensions are one-way distances between the ACA5 Example: Find the 55C. thermal rating factor of a 2000:5 CT whose and the CT. Make sure all secondary extensions meet or exceed the 30C rating factor is 1.3. specifications of the CTs built-in leads. In order to minimize external 2 (85 - 55)(1.3) noise pick up, lead extensions should be as kept short as possible. = 0.96 NRF = 55 6. Accuracy: The indicated accuracy specifications are valid as long as the total secondary burden does not exceed the value in Table 1s Table 1. Selection Guide Lead Ext. Current Accuracy ( Burden VA Thermal Rating UL File CSA File Weight MPS Part No. Feet Leads Type Ratio 60Hz) (Ohms) Factor ( 30C) Cert Cert (lb) (Meters) 7020-01036-0 50:5 2% 1.5 (0.06) 4 (1.2) 1.3 7020-01037-0 75:5 2% 3.0 (0.12) 10 (3.0) 1.3 7020-01038-0 100:5 1% 3.0 (0.12) 10 (3.0) 1.3 16AWG, 24 E175133 Pending 1.5 UL Style 3173 150:5 1% 6.0 (0.24) 20 (6.1) 1.3 7020-01039-0 7020-01040-0 200:5 1% 8.0 (0.32) 30 (9.1) 1.3 7020-01041-0 250:5 1% 10.0 (0.40) 40 (12.2) 1.3 7020-01123-0 300:5 1% 12.5 (0.50) 50 (15.2) 1.0 7020-01124-0 400:5 1% 12.5 (0.50) 50 (15.2) 1.0 E466945 260320 1.0 500:5 1% 20.0 (0.80) 80 (24.4) 1.0 7020-01125-0 7020-01042-0 600:5 1% 10.0 (0.40) 40 (12.2) 1.0 16AWG, 24 UL Style 1015 7020-01043-0 750:5 1% 10.0 (0.40) 40 (12.2) 1.0 7020-01044-0 1000:5 1% 10.0 (0.40) 40 (12.2) 1.0 E228202 223647 1.5 7020-01045-0 1500:5 1% 12.5 (0.50) 50 (15.2) 1.0 2000:5 1% 15.0 (0.60) 60 (18.3) 1.0 7020-01046-0 See www.murata-ps.com/dpm-availability for model-specific availability. www.murata-ps.com/support MPM DMS-CT.B05 Page 2 of 4