Considerations for Grounding Protection of High and low voltage switchgear

2025-10-16 14:29:30

High and low voltage switchgear grounding protection refers to connecting certain conductive parts of electrical devices or facilities in the power system or building to the grounding electrode through a grounding wire. Grounding measures taken to prevent personal and equipment safety in electrical equipment such as metal enclosures, distribution equipment structures, and line towers that may become electrified after insulation damage. However, there are still some issues to be noted when grounding protection for Complete set of electrical switchgear, as follows:

1. To ensure the safety of maintenance work, the main circuit should be able to be grounded. During the maintenance period after opening the casing, it should be possible to connect the main circuit to the grounding electrode.

2. There should be grounding copper bars with a cross-sectional area of not less than 50 × 5 on the cabinet, and there should be copper bar connection plates between each cabinet.

3. The casing should be able to be grounded. All metal parts that do not belong to the main or auxiliary circuits and require grounding should be grounded. The shell, framework, etc. should be able to ensure tight connections to ensure electrical connectivity.

4. The grounding circuit should be able to withstand dynamic and thermal stability tests. The contact surface of the grounding point and the cross-section of the grounding wire should be able to safely pass through the fault grounding current. The diameter of the bolt used to secure the grounding should not be less than 12mm, and the grounding point should be marked with a grounding symbol.

5. Isolation switches and grounding switches should have indications indicating their opening and closing positions and for easy inspection. Isolation switches and grounding switches should not cause accidental disconnection or disconnection due to potential forces during operation.

6. High and low voltage distribution cabinet should be divided into several compartments, which should meet normal operating conditions and limit the arc effect inside the compartments. The partitions between functional units such as busbar room, circuit breaker room, cable room, and relay instrument room are required to be made of galvanized sheet metal.