Method for measuring the polarity of a current transformer - News - Global IC Trade Starts Here Free Join

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

inductance

There are many methods for measuring the polarity of current transformers. The following three test methods are commonly used in our work: 1 DC method; 2 AC method; 3 instrument method.

1 DC method

Use 1.5~3V dry Battery to connect the positive pole to the primary coil L1 of the transformer. L2 is connected to the negative pole. The secondary side K1 of the transformer is connected to the positive electrode of the milliampere meter, and the negative pole is connected to K2. After the wire is connected, the K is closed. The pointer is positively biased, and the pointer of the milliampere meter is negatively biased, indicating that the end of the transformer connected to the positive pole of the battery is the same polarity as the end connected to the positive end of the milliampere meter, that is, L1 and K1 are the same polarity, that is, mutual inductance. The device is reduced in polarity. If the pointer swings opposite to the above, the polarity is added.
2 communication method

Connect the L2 of the primary and secondary coils of the current transformer to the secondary side K2 by wires, and connect the AC voltage of 1~5V on the secondary side (with a small range), and measure the U2 and U3 with a voltmeter of 10V or less. If the value is U3=U1-U2, the polarity is reduced. U3=U1 U2 is the polarity.

Note: In the test process, try to make the input voltage lower, so as not to damage the coil too much. For the reading, the voltmeter should be selected as small as possible. When the converter ratio is below 5, the AC method is simple and accurate. Do not use this method for measurement of more than 10 transformers, because the value of U2 is smaller, the value of U3 is close to that of U1, and the reading of voltmeter is not easy to distinguish, so it is not easy to distinguish when measuring. Generally, it is not suitable to measure polarity by this method. .

3 instrument method

The general transformer calibrator has a polarity indicator. The instrument can check the polarity before measuring the current transformer error. If the indicator is not indicated, the polarity of the current transformer is correct (reduced polarity).