Isolation Verification proves that all sources of energy are removed from equipment prior to conducting maintenance works.  Done correctly it eliminates the risk of the equipment starting while being maintained and therefore injuring people or damaging plant.

Redbusbar Electrical Isolation Verification – Selection Guide

Use the following guide to determine the verification solution for your plant.

Isolator Line side voltage – Verifying an isolator means confirming that no current flows through the switch when a voltage is applied to the line side, with respect to the load side. The voltage may be supplied by the power system, if available, or by the verifying device.  The line side voltage is typically “Alive” for outgoing circuits eg MCC Drive Cells / Buckets and is typically “Dead” for circuits switched upstream eg Field Isolators, all switches during plant wide shutdowns.

Verification Backgound

Electrical Isolation VerificationProof of isolation on electrical powered equipment means confirming that an electrical switch, circuit breaker or disconnect powering the machine is off or open.  Lockout Tagout Verification methods include:

• • Voltage measurement at the load side of the switch – Electrician Test for Dead, Voltage Indicators (DeadEasy), Live Line Indicators (LLI), Absence of Voltage Testers (AVT)
  • Visual check – Plug and Sockets, Visual Break Isolators
  • Attempting to start the equipment after isolating – Try Start / Attempt Start / Bump Start
  • Insulation resistance measurement across the switch contacts – Electrician high voltage resistance test, Automatic high voltage resistance test (SwitChek)

Care is needed when selecting a LOTO verification method.  The method integrity, location, complexity and cost vary greatly.  Learn more in the Technical Paper – Confirming Electrical Isolations