The current transformer is based on the electromagnetic inductionprinciple. It is composed of closed iron core and winding. The turns of its first winding are very small, stringed in the circuit whose current needs to be measured. Thus, it is often flowed through by the full-load current of the line. The turns of its second winding are much than the former, stringed in the measuring instrument and protecting circuit. The circuit of secondary winding is always closed when it works. So the impedance of the measuring instrument and protection circuit is very small, with working status being close to short circuit. It converts the large primary current into the small secondary currents for measuring, meanwhile the secondary winding cannot be opened.

The function of current transformer :

The size of the current varies tremendously in the power generation, power transformation, power transmission, power distribution and power circuit, from several Amp to thousands of Amp. In order to facilitate measurement, protection and control, it needs to be converted to a relatively uniform current. In addition, the voltage of circuit is high and may cause danger when we have a direct measurement. The current transformer plays a role as current transform ing and electri city isolating .

What are the common malfunction of voltage current transformer ? How to judge and handl e it ? What items should be checked during the