Workscope: LVCB Basic Preventive Maintenance

• The circuit breaker will be received and inspected for worn, damaged and missing components
  

  -	Inspection includes, but is not limited to, broken secondary disconnects, bent or damaged interlock arms, rusting on the frame, bent primary disconnects, and missing hardware.
  -	Any items found will be recorded and a suitable replacement identified.

• Arc chutes will be removed, cleaned, and inspected for erosion and damage
  

  -	Arc chutes will be inspected for chipped or broken components and for excessive pitting or burning in the arc path.
  -	Where available, arc chutes as well as other components containing asbestos should be replaced with the manufacturer's recommended non-asbestos parts. These asbestos replacement parts will be quoted at the customer's request.
  -	Upon request, GE will properly dispose of the asbestos-containing materials.

• The circuit breaker will be functionally and operationally tested to determine any additional work required
  

  -	The breaker will be operated and inspected for binding of moving components.
  -	Individual electrical components will be tested as required.
  -	The circuit breaker will be inspected for applicable manufacturer updates.
  -	Any additional work required will be quoted separately.

• Contact assemblies will be cleaned and inspected
  

  -	The contact assemblies will be cleaned in place.
  -	Contact tips with excessive pitting will be cleaned with a burnishing tool.
  -	Contact structure will be inspected for dry lubrication and missing silver plating.
  -	The movable contacts will be inspected for proper alignment and spacing.

• The frame and mechanism will be cleaned and inspected
  

  -	The frame and mechanism will be cleaned with rags and solvent. Where needed, touch up paint will be applied to keep frame from rusting.
  -	The mechanism will be inspected for proper operation, trip shaft torque, dry lubrication, etc.

• The operating mechanism will be lubricated with extended life lubricant
  

  -	Where possible, all bearings and sliding surfaces will be lubricated with the appropriate extended life lubricants.

• Mechanical adjustments will be checked and adjusted as required
  

  -	Wipe and gap measurements will be taken as required.
  -	Mechanism adjustments, such as trip latch wipe, will be completed according to manufacturer's specification.
  -	Quick close mechanism will be checked (if applicable).

• Interlocks, mechanical and electrical, will be checked and adjusted for proper operation, if necessary
• Breaker electrical accessory devices will be tested for proper operation (if applicable). Adjustments will be made as necessary
  

  -	Under voltage device
  -	Shunt trip
  -	Open fuse lock out device
  -	Bell alarm (with or without lock out device)
  -	Auxiliary switch

• Final electrical tests will be performed (if applicable)
  

  -	High current injection tests - Each phase will be checked for over-current and fault protection provided by the trip device.
  -	Contact resistance tests - A digital low resistance ohmmeter will be used to record the contact resistance and compare it to the manufacturer's specifications. High resistance in the contact structure can cause excessive heat in the breaker and prematurely dry out the lubrication.
  -	Insulation resistance tests - A 500 to 1,000 volt megger will be used to determine the condition of the circuit breaker insulation to ground and across phases.
  -	Functional operational tests (electrical and manual) - The breaker will be electrically and manually operated.
  -	Contact overlap sequence tests (AKF field breakers only) - For generator field circuit breakers, the field contact overlap and sequence will be checked and adjusted according to GE specifications.

• Test data will be included as part of the final customer report
  

  -	All test data received will be included with the circuit breaker test report. The test report will be shipped with the equipment.

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