Energy Meter CT's

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A current transformer (CT) is used for measurement of alternating electric current for energy meter. Current transformers, together with voltage (or potential) transformers (VT or PT), are known as instrument transformers. When current in a circuit is too high to apply directly to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.

A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry.

Scope of Application

This specification suitable for 50Hz multi-functional electronic electric energy meter, anti-stealing electric meter, digital meter, also be used for transducer electric variables, remote control data acquisition system, digital relay protection, digital device and meters.

Applicable conditions:

  • Environment temperature:-40 ℃ ~ 85 ℃, relative humidity 95%;
  • Altitude: not more than 1000m;
  • Atmospheric conditions: no serious impact on transformer insulating gas, steam, chemical deposition, dirt and other corrosive, explosive medium.

Technical requirements:

It accords with IEC-60044-1 0.1class, Suitable for Meter standard IS13779

Current transformer specifications

Technical parameters are shown below:

Characteristic Parameter
Working Frequency 50-60Hz
Turn Ratio 1:2500 (+/- 2%)
Overload current Imax x 1.5
DC and even harmonics Imax/√2 as per IEC 62053-21, IEC 62053-23,1inductive , error should be less than ±3%@PF=1.0
Copper Winding SWG 38- 41
Dielectric resistance 4 kVrms for 1 min.
Accuracy Class 0.1-0.5
Insulation Withstand 4000V 50Hz/60 Sec, leakage current <1mA
Magnetic immunity EN50470-3

a. To Continuous magnetic fields of external origin.

b. To Power frequency magnetic fields of external origin 0.5 mT

c. To DC strong magnet 1.2 T Neodymium NeoDeltaMagnet (NdFeB), with surface residual magnetism Br=500mT. The distance from magnet to CT body is approx. 25mm

Secondary Wire PVC or PTFE as per Customer.
UL / ROHS Compliance
Current (Ratio) Error % Phase (angle) Error %
% of rated current % of rated current
5% 20% 100% 100% 100% 20% 100% Imax
-0.4~+0.4 -0.2~+0.2 -0.1~+0.1 -0.1~+0.1 -15~+15 -13~+13 -10~+10 -8~+8

CT drawing

Standard Range of CT:

Current Rating (A) Max OD [A] (mm) Min ID [B] (mm) Max Ht [C] (mm) Wire length [D] (mm) DC immune Magnet Shield Primary BusBar
5-10A 24.5 6.5 14 100 No No No
5-30A 29 8 16 100 Yes No No
5-60A 31 9.5 16 100 Yes No Yes
5-60A 36 9.5 22 100 Yes Yes No
5-80A 26.5 8 11 100 No No Yes
5-100A 36.5 10.5 23 100 Yes Yes No
5-120A 42.5 11.5 23 100 Yes Yes No
5-200A 79.5 39.5 28 150 Yes Yes No
5-320A 46 26 14 150 No No No

Optional Customer Specific:

  • Secondary Wire color code : Red & Black or as per requirement (Red wire in Phase with primary current direction)
  • Secondary Wire type :PVC or PTFE
  • Secondary Wire Twist or straight as per customer.
  • Secondary Wire Insulation Sleeve as per customer.
  • Secondary Wire Length : As per customer requirement.
  • CT Identification : Make, Manufacturing date, Drawing no. Or  As per customer requirement.
  • Lead Type or connector Type as per customer requirement.
  • CT Mounting slot : As per customer requirement.
  • CT Secondary: PCB mounting type or Lead type as per customer requirement.