How do operators/maintenance know when heavy machinery is truly & completely isolated? By turning the dual pole isolator handle to the “OFF” position, is it truly isolated – even if there is an LED/Pilot light indicator installed next to the isolator? Could that indicator light be faulty?
Dirty/Faulty/High Resistance contacts can result in voltage/Back EMF across the poles & can be enough to cause an ignition hazard to personnel carrying out maintenance on the assumed isolated machine/vehicle, along with other associated hazards that fault may cause in the procedure of isolation being required.
The 24VDC solution that can be installed is the Isolation Verification Control. It is a screen that can be installed to show either “LIVE”, “OFF” or “FAULT” status on a screen – no guessing. There should always be a visual, positive status of indication on the screen. If, in the remote chance that there is no screen indication at all, maintenance must be notified to investigate the issue.
