Answer: When the power system resonates, there will be several times to dozens of times the rated voltage of over-voltage and over-current, porcelain insulator discharge, insulator, casing and other iron corona, voltage transformer fuse, serious damage to equipment.

Three-phase AC power supply line in the wear metal pipe, why can not use single-phase in charge of threading?

Answer: If a single phase wire is used to pass through the pipe, because the metal pipe is a closed magnetic conductive circuit, the induced magnetic flux in the metal pipe will increase with the increase of the current flowing through the wire, resulting in eddy current and induced voltage in the metal pipe, causing the metal pipe to heat up, threatening the safe operation of the line, and also increasing the power loss of the line.

Under what circumstances should the power cable be protected through the pipe?

Answer: In order to ensure that the cable is not damaged by external force during operation, it should be protected under the following circumstances.

(1) Cable leads to and from buildings, tunnels, trenches, etc.

(2) The cable passes through roads, railways, etc.

(3) When the cable is led out or introduced into the ground, the section 2m from the ground to 0.1~0.25m underground shall be equipped with protective pipe.

(4) Crossing of cables with various pipes and channels.

(5). Areas where the cable may be mechanically damaged.