Safety Points For Mining Distribution Boxes

Mining distribution boxes are used in mining environments characterized by high humidity, dust, and the risk of gas or coal dust explosions. Their safety is directly related to the safety of mine power supply, equipment operation, and the lives of workers. The following are the core safety points:

I. Selection and Installation

1. Explosion-proof Rating:

The appropriate explosion-proof type and rating must be selected based on the specific area of ​​the mine.

Key Markings: The nameplate must be marked with the "Ex" explosion-proof mark and the "MA" mining product safety mark; otherwise, it is strictly forbidden to put them underground.

2. Casing:

Before installation, the casing must be inspected for cracks, deformation, and severe corrosion.

The explosion-proof surface must be smooth, free of rust and scratches, and coated with anti-rust oil. Excessive explosion-proof gap tolerance is a major cause of explosion propagation.

3. Cable Entry Device:

Qualified metal or rubber sealing rings must be used, and they must fit tightly with the cable's outer diameter.

Multiple cables in one opening or the use of substandard materials for sealing are strictly prohibited.

Any excess cable inlets must be sealed with metal plugs of equivalent explosion-proof rating.

4. Grounding System

Protective and auxiliary grounding must be implemented according to regulations.

The cross-sectional area of ​​the grounding connection wire and the burial depth of the grounding electrode should comply with the "Coal Mine Safety Regulations," and the grounding resistance must meet the standards.

 

II. Operation and Maintenance

1. Cover Opening Alarm/Power Off: Distribution boxes used in underground coal mines should have an "open cover alarm" or "open cover power off" function to prevent accidental operation.

2. Regular Cleaning: Clean the exterior of the box and the heat sink of coal dust at least once a week to prevent accumulation and burial that affects heat dissipation; internal cleaning must be carried out after power is off, according to the instruction manual.

3. Moisture and Condensation Prevention: Check if the desiccant inside the box is ineffective; observe for condensation. In humid environments, use a hot air blower to dehumidify regularly.

4. Tightness and Temperature Rise Check: Regularly check all wiring terminals for looseness using explosion-proof tools; during operation, monitor the temperature of each phase connection point and the outer casing with an infrared thermometer; there should be no obvious hot spots.

5. Closing Operation: It is strictly forbidden to directly open or close the isolating switch under load.

 

III. Emergency Handling

1. Do not forcibly restore power to abnormal tripping: If the distribution box trips frequently or the cause cannot be found after tripping, it is forbidden to repeatedly force power back on. Power can only be restored after the fault point has been identified and resolved.

2. Immediate Shutdown for Abnormal Casing Temperature

If excessively high localized temperatures are detected on the casing of the distribution box during operation, it may indicate internal contact corrosion or a short circuit hazard. Power should be immediately cut off and the box inspected.

3. Fire Response

If a fire breaks out inside the distribution box, do not pour water directly on it to avoid short circuits or electric shock. Use dry powder or carbon dioxide fire extinguishers or cover the fire with sand.

 

IV. Supplementary Information for Special Environments

High-sulfur mines: Corrosion-resistant distribution boxes must be selected. Grounding wires and fasteners should be galvanized or made of stainless steel.

High altitudes: Pay attention to the insulation gap and breaking capacity of the distribution box; derating or selecting a special model may be necessary.

Mobile equipment platforms: Distribution boxes require additional shock absorption and fixation; cable entry points should use anti-pull-out structures.