Current transformer for Electricity meters

We manufacture and supply many types of current transformer for Electric energy meter, the CT adopted high permeabilityMu metal and nanocrystalline core, with high accuracy class and good linear performance, conform to industrial standard JB/T10665-2016 for current transformer and international standard IEC60044 , In further, the CT will be inspected as per the standard JJG313-1994.

According to different installation method and performance requirements, the CTs will be classified as below：

CT for state grid electricity meter – S series

Straight-through current transformer - C series

CT with terminal – Y series

PCB mounting – P series

DC immunity CT –D series

Combined CT – Z series

Magnetic field immunity – T series

Power CT –G series

Transformer for detection and protection in instruments-G series

Technical requirements

Usage conditions

Working temperature -25℃～+75℃, humidity＜90%（25℃）;

No strong electromagnetic field in operating environment;

No gas, steam, chemical sediments, dust, and others harmful medium that might seriously affect the insulation of the CT;

Rated voltage 500V, waveform of the power supply, sine wave waveform distortion coefficient: no more than 5%

Schematic Diagram:

Ratio error

The error while testing current, it caused by different between actual current ratio and rated current ratio , it can be calculated in accordance with following formulas:

Current error=（KnIs—Ip）/Ip×100%

Kn:  rated current ratio

Ip:  actual primary current ( unit:A)

Is:   actual secondary current while doing test by input Ip ( Unit: A)

Phase Error

It means the phase position difference between vector of primary current and vector of secondary current, Vector direction is subject to ideal current transformer whose phase error is zero. If secondary current vector is ahead of primary current vector, then phase error is positive number, its unit is usually sub-arc or arc.

The error ranges of current error and phase difference of transformers with different precision grades are as follows:

Class	Ratio error（±%） In the percentage of (%)of input current				Phase error（′） In the percentage of (%) of input current
	5％Ib	20%Ib	100%Ib	120%Ib	5％Ib	20%Ib	100%Ib	120%Ib
0.1	0.4	0.2	0.1	0.1	15	8	5	5
0.2	0.75	0.35	0.2	0.2	30	15	10	10
0.5	1.5	0.75	0.5	0.5	90	45	30	30
1.0	3.0	1.5	1.0	1.0	180	90	60	60
0.2S	0.75	0.35	0.2	0.2	30	15	10	10
0.5s	1.5	0.75	0.5	0.5	90	45	30	30

Insulation intensity with power frequency

Insulation of the primary winding to the secondary winding and to the earth can withstand a voltage of 3KV with power frequency lasting for 1 minute.

Turn to turn insulation intensity

With opening circuit at the secondary winding, the turn-turn insulation of the CT won’t be damaged

when the primary winding pass rated current at rated frequency lasting for 1 minute.

Insulation strength

Primary winding to Secondary winding≥1000MΩ（DC500V）

DC tolerance

As following figure, test the DC error of the CT after install the electricity meter,

0.1 Class CT will be controlled within±3.0% ,  0.2 Class CT will be controlled within±6.0% ,