Current Transformer Considerations

- Sep 10, 2018-

Current Transformers-Precautions for use when the current transformer is running, the side edge is not allowed to open the road. Because once the open circuit, the original edge current becomes the excitation current, so that the flux and side voltage greatly exceed the normal value and endanger the safety of the person and equipment.

Therefore, the current transformer side circuit is not allowed to connect the fuse, nor is it allowed to remove the ammeter, relays and other equipment without bypass at run time. When the current transformer is running, the secondary edge is not allowed to open the road.

The reasons are as follows:

1.current transformer is measured at one current magnetic potential i1n1 in the iron core to produce flux φ1

2.current transformer Two measurement instrument current magnetic potential i2n2 in the iron core to generate magnetic flux φ2

3.current transformer iron core bonding flux: φ=φ1 +φ2

4.because the φ1.φ2 direction is opposite, the size is equal, offset each other, so φ= 0

5.If the open circuit two times, that is, I2 = 0, then: φ=φ1, the current transformer iron core flux is very strong, saturated, core heat, burnout insulation, resulting in leakage

If the 6.opens two times, that is, I2 = 0, then: Φ=φ1,φ produces a high inductive potential e in the current transformer two coil N2, forming high pressure at both ends of the current transformer two coils, endangering the operator's life safety.

7.current transformer grounding at one end of the two-time coil is a protective measure taken to prevent high pressure hazards.