Current transformer open circuit preventive measures

- Dec 11, 2019-

In the electrical safety work regulations, it is stipulated that the secondary side of the current transformer must be grounded. The purpose is to prevent the primary side insulation and high pressure from entering the secondary side, causing damage to the human body and the secondary side meter. Therefore, the secondary side of the current transformer must be grounded.

 

When the secondary open circuit fault of the current transformer occurs, the correct and safe treatment method is: power off the high voltage side, and process it (return the open circuit point to the normal loop state), but this will cause unplanned power outage;

 

The unconventional treatment method is: because the open circuit of the current transformer has a discharge phenomenon, it is easier to find. One wire can be used (the wire diameter should meet the rated secondary current requirement of the current transformer, the rated secondary current of the current transformer is 1 amp or 5 amps, and the wire can be fully used with 2 square meters). First, the wire ends with the open coil. The grounding terminal is connected, and the other end of the wire is connected to the farther fixed connection point of the open point by the insulating tool (the insulation of the general screwdriver handle) to achieve the purpose of shorting the open circuit point, which is relatively easy. The grounding point is treated to avoid equipment blackout. This method is not recommended from the perspective of safety, but in order to avoid the occurrence of assessment accidents, it can be completed by experienced secondary system staff.

 

Precautions for the open circuit of the secondary circuit of the current transformer:

(1) The secondary circuit of the current transformer is not allowed to be equipped with a short circuit protection device such as a fuse;

(2) The secondary circuit of the current transformer generally does not switch. When it is necessary to switch, there should be reliable measures to prevent open circuit;

(3) The relay and the measuring instrument generally do not use the current transformer. When it is necessary to use it, the measuring instrument should be connected through the intermediate converter;

(4) For current transformers that have been installed and not used, the terminals of the secondary winding must be shorted and grounded.

(5) Terminals of the secondary circuit of the current transformer should use test terminals

(6) It should be ensured that the connecting wires of the secondary circuit of the current transformer have sufficient mechanical strength.

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