The device was designed to provide an isolation position for 3.3kV circuits during longwall maintenance tasks that was quicker, safer and more positive than current systems.

Longwall Advantage said it started with a concept after Brett Morris from the Beltana mine approached the company detailing problems associated with 90% of production tasks requiring isolation but not earthing.

“After three month of design review and prototyping we arrived at the final design,” the company said.

“After internal and minesite risk reviews the assembly was tested at Beltana in the midst of a longwall move, and was well received.”

The operator simply turns off the outlet as per mine procedures, racks out the plug and withdraws the plug to the isolate position and places his lock or scissor.

The carriage takes all the weight of the plug and cable, there is no finger access to the receptacle pins and the operator can see a break between the power pins and sockets.

After the maintenance task is completed the locking pin is removed, which is spring-pin operated, and the plug inserted into the receptacle. The cradle again guides the components together, preventing damage to the flame paths.

For electrical maintenance tasks where earthing is required, the plug is withdrawn and simply inserted as normal into an earthing receptacle that is fitted with a carriage. The plug can then be locked only in the earthed position.

The product suits 300 amp and 425A 3.3kV plugs and sockets.