Ten Points to Note in the Use of Current Transformer

20Dec

Ten Points to Note in the Use of Current Transformer

 

Ten Points to Note in the Use of Current Transformer

1. The secondary side of the CT shall not be open during operation.
Because the secondary impedance of the CT is very small, the secondary side is close to the short-circuit state during normal operation.
When the secondary side is open, high voltage will be induced, endangering the safety of people and equipment.
Therefore, the secondary side of the CT is not allowed to open the circuit. The wiring of the secondary circuit must be reliable and firm, and it is not allowed to connect the switch or fuse in the secondary circuit. Use circular crimping terminals when wiring. During disassembly and assembly, the two wire ends of the secondary side should be short-connected before disassembly and installation and replacement of instruments can be carried out to ensure the safety of people and equipment.

2. The primary winding of the CT is connected to the side circuit in series, the secondary winding is connected to the side basin instrument, and the polarity of the primary and secondary coils is correct.

3. The primary winding and core of the CT should be reliably grounded.

4. The load impedance of the secondary side shall not be greater than the rated load impedance of the CT to ensure the accuracy of the side measurement.

5. The current transformer shall not be connected with the secondary side of the voltage transformer, so as to avoid the risk of high voltage due to the current transformer’s approximately open circuit.

6. One end of the secondary side of the CT must be grounded to prevent the high voltage of the primary side from penetrating the secondary side when the insulation of the primary and secondary windings breaks down, endangering the safety of people and equipment.

7. When individual current transformers are damaged in operation and need to be replaced, they shall be used with voltage grade no lower than the rated voltage of the power network, with the same ratio as the original, correct polarity and similar volt-ampere characteristics, and pass the test.

8. The current transformers need to be replaced in groups due to capacity changes, and the setting value of relay protection and the rate of the metering instrument should be reviewed again.

9. When the secondary side cable is replaced, its cross section and core number must meet the requirements of maximum load turtle current and total load impedance of the circuit shall not exceed the allowable value of the current transformer’s accurate grade. Besides, the insulation resistance of the new cable should be measured.

10. The polarity of the current transformer and the secondary circuit after replacement must be determined before operation.

Ten Points to Note in the Use of Current Transformer


1. The secondary side of the CT shall not be open during operation.

Because the secondary impedance of the CT is very small, the secondary side is close to the short-circuit state during normal operation.

When the secondary side is open, high voltage will be induced, endangering the safety of people and equipment.

Therefore, the secondary side of the CT is not allowed to open the circuit. The wiring of the secondary circuit must be reliable and firm, and it is not allowed to connect the switch or fuse in the secondary circuit. Use circular crimping terminals when wiring. During disassembly and assembly, the two wire ends of the secondary side should be short-connected before disassembly and installation and replacement of instruments can be carried out to ensure the safety of people and equipment.


2. The primary winding of the CT is connected to the side circuit in series, the secondary winding is connected to the side basin instrument, and the polarity of the primary and secondary coils is correct.


3. The primary winding and core of the CT should be reliably grounded.


4. The load impedance of the secondary side shall not be greater than the rated load impedance of the CT to ensure the accuracy of the side measurement.


5. The current transformer shall not be connected with the secondary side of the voltage transformer, so as to avoid the risk of high voltage due to the current transformer’s approximately open circuit.


6. One end of the secondary side of the CT must be grounded to prevent the high voltage of the primary side from penetrating the secondary side when the insulation of the primary and secondary windings breaks down, endangering the safety of people and equipment.


7. When individual current transformers are damaged in operation and need to be replaced, they shall be used with voltage grade no lower than the rated voltage of the power network, with the same ratio as the original, correct polarity and similar volt-ampere characteristics, and pass the test.


8. The current transformers need to be replaced in groups due to capacity changes, and the setting value of relay protection and the rate of the metering instrument should be reviewed again.


9. When the secondary side cable is replaced, its cross section and core number must meet the requirements of maximum load turtle current and total load impedance of the circuit shall not exceed the allowable value of the current transformer’s accurate grade. Besides, the insulation resistance of the new cable should be measured.


10. The polarity of the current transformer and the secondary circuit after replacement must be determined before operation.