The difference in current and voltage in the power supply line varies from a few amperes to tens of thousands of amperes. In order to facilitate the measurement of the secondary instrument, it needs to be converted into a relatively uniform current. In addition, the voltage on the line is relatively high, such as direct measurement, which is very risky. The current transformer plays the role of current conversion and electrical isolation. The matters needing attention during the operation of the current transformer are as follows:

　　 The secondary side of the current transformer must not be open during operation. Once the secondary side is open, it will burn out due to excessive iron loss and high temperature, or the voltage of the secondary winding will increase and the insulation will break down, resulting in the risk of high-voltage electric shock. Therefore, when changing meters, such as interchange of ammeters, active meters, and reactive meters, the current loop should be short-circuited before the metering meter interchange should be stopped. When the meter is adjusted, first connect it to the secondary circuit and then remove the short wiring and check whether the meter is normal. If sparks are found when the short wiring is removed, the current transformer has been opened at this time, and the short circuit should be re-shorted immediately. Only when it is found that there is no open circuit in the meter circuit, can the short wiring be removed again. When you stop removing the short circuit of the current transformer, you should stand on the insulating pad. In addition, consider stopping the maintenance and installation of the current transformer circuit. After the work is completed, the maintenance and installation can be put into operation.

　　 When the insulation resistance of the secondary coil of the current transformer is lower than 10-20 megohms, the drying process must be stopped to restore the insulation before it can be used.

　　 One end of the secondary side of the current transformer, and the shell must be firmly grounded.

　　 If the current transformer has a buzzing noise, check whether the internal dead center can be loosened, and tighten the dead center bolt.