For the disconnection of the voltage transformer circuit, handle it according to the following three steps:
(1) According to the relevant regulations of relay protection and automatic devices, exit the relevant protection to prevent misoperation;
(2) Check the high and low voltage fuses and the automatic switch. The dual-clamp phase volt-ampere meter can conveniently measure the phase between U-U, I-I, and U-I on site, distinguish inductive and capacitive circuits and the phase sequence of three-phase voltages, detect the connection group of transformers, and test whether the secondary circuit and bus differential protection system are normal. If the fuse is blown, find out the cause and replace it immediately. If it blows again, handle it with caution;
(3) Check all joints in the voltage circuit for looseness or broken wires, and check the switching circuit for poor contact.
For the open circuit of the current transformer secondary circuit, handle it according to the following two steps:
(1) Immediately report to the dispatcher on duty and exit the relevant protection according to the regulations of relay protection and automatic devices;
(2) Identify the fault point, and under the premise of ensuring safety, try to short-circuit it on the terminal near the open circuit. Do not use fuses for short-circuiting. If the open circuit cannot be eliminated, consider power outage for handling.
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