THE Queensland Mines Inspectorate has released a safety alert following two incidents at longwall mines in which cables and plugs were blown out their receptacles.
According to the authority, the first incident occurred when an armoured face conveyor (AFC) stopped. When the operators attempted to restart the machine, a large arc occurred and the tailgate feeder cable was blown out of the back of a flameproof restrained plug.
A maintenance fitter nearby was uninjured, and the plug was reinserted and restrained with a quick release back-to-back coupler.
In a second incident, a cable receptacle suffered a catastrophic failure when a crusher motor was starting up. The cable plug was blown out of the receptacle.
Both the faulty plug from the first incident and the receptacle in the second incident were Minto 3.3kV 300 Amp flameproof components.
The inspectorate says the dangers of malfunctioning flameproof equipment in hazardous zones underground was compounded by the dangers to coal mine workers from the failure of electrical equipment.
The authority recommends mining operators ensure documented certification requirements are met in all aspects of an installation. Maintenance personnel should pay special attention to areas of interior mouldings, grommet size and cable size. They should ensure cable management processes effectively support and anchor cables.
Original equipment manufacturers were urged to provide the correct dimensions for termination of the cable cores into restrained plugs in their documentation.
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