How to ground the pad-mounted substation

Electrical grounding is to connect a ground wire to the metal casing of the equipment; use the earth as a current loop grounding wire to protect the equipment and personal safety. Therefore, the grounding of electrical equipment is very heavy, and the grounding must be correct to avoid a series of accidents caused by grounding. For the ground problem of pad-mounted substations, the same is true.

Pad-mounted Substation Grounding:

Correctly select low-voltage public grounding bus.

“High-voltage/low-voltage pre-installed Pad-mounted substation selection guideline” DL/T537　2002 article 5.1 stipulates: the grounding conductor should use copper conductor, and its minimum cross-sectional area should not be less than 30mm2.

Some boxes have become cost-saving and the use of aluminum is not in compliance with the requirements of the regulations. This line does not pass the working current, and at the same time, this line has an important role in effectively reducing the fault contact voltage and preventing electric shock.

After the cross-sectional area of this line is increased, the selection area of the conductive circuit in the Pad-mounted substation can be greatly reduced after calculation, so it should be more cost-effective to reduce the overall cost.

The grounding grid of the Pad-mounted substation should be buried below 1m deep

The foundation of the Pad-mounted substation is generally less than 10m2, and the size is relatively small, while the grounding grid is relatively large, and it needs to be extended to the farther area around it. In order to reduce the grounding resistance, some vertical grounding electrodes must be added.

In order to reduce the ground voltage distribution and not cause other damage to the surroundings, the grounding grid should be buried as deep as possible. At the same time, the connection point between the grounding grid and the Pad-mounted substation should be firmly connected at least in two or more places according to the requirements of countermeasures, and the connection area should meet the requirements.

The inside of the Pad-mounted substation box shall be connected to the ground potential as required to create an equipotential environment to protect the operation and maintenance of the Pad-mounted transformer.