
Enclosure Electrical Interlocks

When an industrial control panel controls industrial machinery, and operates with a voltage more than 50 V AC / 60 V DC, each door of the control panel must be locked so that the door can only be opened when the disconnecting means is switched off. Door interlocking can either be mechanical or electrical, and must meet the following conditions. The interlocking must be activated automatically when closing the doors without additional measures. It must be possible for an authorize person to defeat the interlock with a tool so that the door can be opened for maintenance and service, with the main switch staying on.
Hoffman PROLINE G2 Mechanical Interlocks utilize a ½ inch aluminum hex rod, which feeds through door actuators positioned at the top of the enclosure. The door-mounted activator brackets engage with the actuators, and the combination of the actuators and a hook and capture system, increases the safety by preventing system re-energization without closure of all secondary doors and the primary door.
Hoffman Electrical Interlocks provide positive internal safety lockout on electrical enclosure while the equipment is energized. When energized, the interlocks prevent the door handle from being turned to open the door.
Hoffman Electrical Interlock Defeaters enable authorized personnel to enter an enclosure while the enclosure equipment is energized. Defeaters are key-operated, momentary contact switches with contacts normally closed. Turning the key disengages the circuit to the electrical interlock. They can be used with ll 110/120 V Hoffman electrical interlocks.