Choice of MV switchgear panel for a transformer circuit

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Three types of MV switchgear panel are generally available:

  • Load-break switch and separate MV fuses in the panel
  • Load-break switch/MV fuses combination
  • Circuit-breaker

Seven parameters influence the optimum choice:

  • The primary current of the transformer
  • The insulating medium of the transformer
  • The position of the substation with respect to the load centre
  • The kVA rating of the transformer
  • The distance from switchgear to the transformer
  • The use of separate protection relays (as opposed to direct-acting trip coils).

Note: The fuses used in the load-break/switch fuses combination have striker-pins which ensure tripping of the 3-pole switch on the operation of one (or more) fuse(s).

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