LVCB Comprehensive Preventive Maintenance and Conversion

Workscope: LVCB Comprehensive Preventive Maintenance and Conversion

  • 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 recommend 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.
  • Breaker contact assemblies will be disassembled as necessary to thoroughly inspect and clean
    - Disassembly and cleaning of the contact structures reduces the amount of resistance in and heat generated by the current carrying path. This process also removes all of the dried lubrication found in the contact structure.
    - The contact assemblies will be removed from the circuit breaker and disassembled into component parts.
    - All contact assembly components will be inspected for damage and wear.
    - All components will be cleaned and the contact structures re-assembled using extended life lubricants.
    - After re-assembly, contact pressure will be checked and adjusted according to manufacturer's specifications.
  • 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.
  • The circuit breaker's front frame and back frames will be assembled, and the appropriate conversion kit installed
    - Replacement of old electro-mechanical trip devices with new current generation digital trip devices increases the flexibility and reliability of your existing circuit breakers.
    - GE currently offers three different types of conversion kits: the MicroVersaTrip Plus™ (M or PM), the ProTrip and the Carriere conversion kit.
    - The existing trip devices and components will be removed to make room for the conversion kit.
    - The conversion kit will be installed according to manufacturer's specifications and all components verified for correct installation.
  • 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, as 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 the 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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