MV AC Switchgear

Medium voltage switchgear buses typical failures

Electrical buses are an integral part of the medium-voltage switchgear and are used as a connection point to distribute electric power to various parts of the facility. A bus consists of metallic bus bars which are energized at the rated nominal system voltage level. The bus bars are usually made of solid copper metal bar that are silver and/or zinc plated, metal tubing, or flexible cable and are supported by insulators. Cable leads are attached to the bus to connect the various loads to be supplied. Aging stressors that may cause degradation of electrical buses primarily include exposure to moist or humid air,which can lead to corrosion of the metallic components, as well as exposure to high voltage arcing, which can degrade the various insulators used to support and isolate the bus bars. Vibration and thermal cycling can also lead to loosening of connections. Electrical transients can produce substantial electromagnetic forces that can crack,damage,or displace bus support insulators,connections, and associated hardware to secure these supports.examples of busbar failures:

  • Short to ground
  • Phase-to-phase short
  • Corona and tracking

Pic show a busbar failure in switchgear

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