Workscope: Substation - Low Voltage Switchgear

• Before any work is performed, all lock out and tag out procedures will be followed to ensure that the equipment is de-energized and safe for maintenance. The switchgear cubicles and circuit breaker compartments will be cleaned and inspected for evidence of damaged or defective devices
  

  -	The cubicles will be inspected for damaged or missing components.
  -	Where applicable, the circuit breakers will be racked in and out to verify proper operation of racking mechanism.
  -	Cubicle primary and secondary disconnects will be inspected and cleaned.
  -	Cubicle wiring will be inspected for damaged wires and connection tightness.
  -	Any item found damaged will be recorded and a suitable replacement identified.

• Compartment space heaters will be inspected for proper operation
• Protective interlocks will be checked for proper operation
  

  -	Positive, negative and racking interlocks will be checked for proper operation.
  -	Circuit breaker interference plates will be checked against the manufacturer's specifications for appropriate location.
  -	Any item found damaged will be recorded and a suitable replacement identified.

• All circuit breaker compartment function positions (disconnect, test and connected) will be checked for proper operation
  

  -	The breaker racking mechanism will be racked to all positions and any indicators checked for indication of proper position.

• The bus insulation will be inspected for evidence of overheating, electrical tracking or weakening of the insulation supports
  

  -	The bus insulation will be inspected for signs of corona or tracking.
  -	The insulation will be cleaned with solvent and rags as applicable.
  -	Any item found damaged will be recorded and a suitable replacement identified.

• Bolted pressure connections will be checked for proper torque (tightness) where possible
  

  -	Bolted connections, where accessible, will be checked for proper torque according to applicable standards.
  -	Ground bus connections and supports will be checked for proper tightness.
  -	Compartment panel door latches will be checked for proper operation.
  -	Compartment door latches will be checked for smooth operation and that the doors close completely.
  -	For outdoor switchgear, gaskets and outdoor latches will be checked for condition.
  -	Any item found damaged will be recorded and a suitable replacement identified.

• The circuit breaker elevating/racking mechanism will be cleaned, inspected and lubricated using extended life lubricants
  

  -	Jack screws and other racking mechanism components will be checked for proper operation.
  -	Where possible, racking mechanism components will be lubricated.

• All potential transformer and control power transformer compartments will be cleaned and inspected
  

  -	All PT and CPT fuse clips and fuse ferrules will be inspected and cleaned.

• Final electrical tests will be performed, as applicable
  

  -	Insulation Resistance Tests - A 500 to 1,000 volt megger will be used to determine the condition of the circuit breaker insulation to the ground and across phases.

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Related Information

• Low/med voltage circuit breakers
• High voltage circuit breakers
• Motor starters
• Substation maintenance
• Protective relays
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