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Extending the Life of Existing Switchgear


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Copyright AIST Reprinted with Permission. Presented at the 2013 Iron and Steel Technology Conference and Exposition (AISTech 2013). In an industrial facility, nothing operates without a reliable flow of electricity. Therefore, it is critical to properly maintain the switchgear and switchboards that distribute electricity through the power system. Switchboards are more commonly used in commercial and light industrial Low Voltage applications, while switchgear is usually specified in heavy industrial Medium Voltage applications, where the demands on the equipment require more robust construction.

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Extending the Life of Existing Switchgear

  1. 1. Miklos J Orosz Senior Staff Engineer Schneider Electric Extending the life of existing switchgear
  2. 2. In an industrial facility, nothing operates without a reliable flow of electricity
  3. 3. With increasing dependence on computers and automated processes, most modern facilities cannot afford downtime Electrical Systems are Serious Business
  4. 4. Switchgear Reliability and Longevity Requires two fundamental activities Preventive Maintenance Periodic Updating
  5. 5. Preventive Maintenance Having a preventive maintenance program in place can, in many cases, double the life of existing switchgear.  According to IEEE, the rate of electrical component failures is three times higher in facilities that do not perform preventative maintenance on their electrical systems.  Contributing factors  Mechanical failure (43%)  Loose connections, overheating, load changes/additions  Environmental conditions (17%)  Humidity, dirt/dust or corrosive environments  May impace the OEM’s recommended maintenance schedule  Work improperly performed (17%)  NFPA 70B 3.3.58 states that equipment maintenance is to be performed by a qualified person
  6. 6.  Inspection  Cleaning and lubrication  Adjustments  Over-current protective device testing  Insulation testing  Charge/close/trip circuit testing  Dielectric testing  Time and speed testing Fundamental Circuit Breaker Maintenance Activities
  7. 7. Circuit Breaker Technology Essentially four types of medium voltage circuit breakers Based on the arc quenching medium  Oil Air SF6 Gas Vacuum Typically are draw-out type
  8. 8. Modernization Retrofitting is a general term that is used to define any process which allows for modernization and life extension of electrical equipment Maintaining the core switchgear structure, conduits, cabling and footprint are left intact, which saves time and money Modern circuit breaker technology have a longer life-cycle helping extend overall switchgear life
  9. 9. Eight Reasons to Modernize Upgrade Circuit Breaker  Improve ratings  Environmental impact and hazards  Performance and safety improvements  Meet current ANSI Standards  Improve reliability  Reduce maintenance cost  Reduce size and weight  Unforeseen cost considerations
  10. 10. Eight Reasons to Modernize Upgrade Circuit Breaker 1.Improve Ratings Switchgear frame or enclosure, and bussing, are usually higher rated than the circuit breakers Circuit breakers can be upgraded at least one class  i.e. from 25kA short circuit interrupting capability to 40kA  In many cases even higher up to 50kA Modern vacuum circuit breakers are also faster, most of them have short circuit current interrupting rating of 3 cycles or less  Older circuit breakers have interrupting time of 5 or 8 cycles, or more
  11. 11. Eight Reasons to Modernize Upgrade Circuit Breaker 2. Environmental impact and hazards Many old design air magnetic circuit breakers used asbestos based arc chutes The oil used in oil circuit breakers may contain hazardous chemicals SF6 gas was recently declared a green house gas New technology of vacuum interrupters can help resolve environmental concerns
  12. 12. Eight Reasons to Modernize Upgrade Circuit Breaker 3. Performance and safety improvements Fault current interruption New circuit breakers are available with higher ratings In most cases, the interruption capacity of the entire switchgear can be increased with an engineering study and a circuit breaker upgrade or replacement Arc flash limiting circuit breaker availability Trip unit accuracy and repeatability with new circuit breakers Power metering, monitoring, and communication
  13. 13. Eight Reasons to Modernize Upgrade Circuit Breaker 4. Meet current ANSI Standards Vacuum circuit breakers are operating with the voltage factor K=1 Interrupting capability is not affected by the system voltage Vacuum circuit breakers with an assigned short circuit current interrupting capability will function at any voltage level without reducing the assigned short circuit interrupting rating More flexibility for interchangeability of the new circuit breakers
  14. 14. Eight Reasons to Modernize Upgrade Circuit Breaker 5. Improve Reliability Electromechanical trip interrupting devices on existing circuit breakers may have reliability issues: Many do not trip at all Those that trip are not repeatable and may be well outside the time-current coordination parameters Aging materials reduce equipment reliability due to: Dielectric breakdown of insulating components Degradation of aging mechanical parts
  15. 15. Eight Reasons to Modernize Upgrade Circuit Breaker 6.Reduce Maintenance cost Older power circuit breakers require extensive periodic maintenance and overhaul Expensive and time consuming Lengthens outages May require extensive outside support Many components for existing and older circuit breakers are no longer available Quantity and quality of used or reconditioned parts is decreasing and unreliable Prices of replacement parts are increasing
  16. 16. Eight Reasons to Modernize Upgrade Circuit Breaker 7. Reduce size and weight 30% to 60% weight reduction can be achieved by using new vacuum technology. Can improve maintenance access and transportability
  17. 17. Eight Reasons to Modernize Upgrade Circuit Breaker 8. Unforeseen cost considerations  Several factors influence the cost when considering upgrades Cost of new equipment VS. retrofit/ upgraded equipment Plant maintenance cost analysis Additional space requirements Construction cost Installation cost Removal of existing equipment Disposal of existing equipment Labor cost of training maintenance personnel Downtime cost Cost of Production loss
  18. 18. Updated with New Technology Original air magnetic circuit breaker with asbestos based arc chutes Direct replacement modern vacuum circuit breaker
  19. 19. Thank You Miklos J Orosz Senior Staff Engineer Schneider Electric