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How To Measure The Polarity Of Current Transformer
Oct 12, 2017

How to measure the polarity of current transformer

Key words: summary of how polarity current transformer measurement: current transformer should be polarity test before and after the handover and overhaul, in order to prevent the wiring polarity mistake, resulting in the relay protection circuit and measuring circuit protection device and error action caused cannot be measured correctly, so we must do polar test before put into operation. There are many ways to measure the polarity of current transformer. We usually have three kinds of test methods in our work. One is direct current method, the other is communication method.

The current transformer should be polarity test before and after the handover and overhaul, in order to prevent the wiring polarity mistake, resulting in the relay protection circuit and measuring circuit protection device and error action caused cannot be measured correctly, so we must do the polarity test before put into operation.

There are many ways to measure the polarity of current transformer. We usually have three kinds of test methods in our work. One is direct current method, the other is communication method.

1 DC method

1.5 ~ 3V dry battery will be a coil connected to the anode of L1 transformer, L2 transformer is connected to the anode, the two side K1 milliammeters cathode electrode with K2, after connection, K will close the milliammeters pointer is opened, after milliammeters pointer negative bias, that end the first transformer is connected to the battery anode and the end connected to the positive terminal to milliammeters polarity, namely L1 and K1 are that the transformer is reducing polarity.

2 alternating current method

The current transformer secondary coil one or two L2 and two K2 side connected by wires, in the two side with AC voltage of 1 ~ 5V (with small range), with the following 10V numerical voltage meter measuring U2 and U3 if U3=U1-U2 is minus polarity.

U3=U1+U2 is additive polarity. Note: during the test to pass into the low voltage, so as to avoid damage to the coil current is too large, in order to clear reading table to choose some small voltage, current ratio below 5 when compared with AC measurement method is simple and accurate, to measure the current ratio transformer should not exceed 10 by using this method, because close to the values of U3 and U1 small U2, meter reading is not easy to distinguish between the size, so when measurement is not to identify the measuring polarity by generally not.

3 meter method

The general transformer calibrator has polarity indicator. Before measuring the error of current transformer, the instrument can check polarity in advance. If the indicator is not indicated, the polarity of current transformer is correct (polarity reduction).


Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com