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Generator circuit-breaker VD4G up to 63 kA

Cost-optimized solutions for generators up to 90 MW

VD4G is a generator circuit-breaker (GCB) with vacuum interrupting technology for short circuit currents up to 63 kA, 15 kV and rated currents up to 3,150 A with natural cooling (4,000 A with forced cooling) suitable for generators up to 90 MW.

Based on the well-proven and highly reliable VD4 platform with over one million installations since 1986, the VD4G is tested to meet the most stringent IEEE and IEC requirements for generator applications as per IEEE C37.013 and the new revision IEC/IEEE 62271-37-013, the only standards for GCB worldwide.

VD4G is capable of interrupting currents with delayed zero crossings that may occur in the event of faults that are fed from the generator, or faults during synchronization with the high-voltage grid. Its interrupting technology enables withstand severe transient recovery voltages (TRV) to protect critical equipment. It has excellent duty in terms of maximum number of switching operations and is maintenance free. With its compact dimensions, VD4G is suitable for installation in standard medium-voltage switchgear for the most cost-optimized solution.


  • Generator circuit-breaker for power plants up to 90 MW
  • Renewable power generation
  • Networks with emergency power generators
  • Process industry with own power generation

Why Hitachi Energy?

  • The only manufacturer to provide GCB for power plant up to 2,000 MW
  • Fully tested according to IEC/IEEE 62271-37-013, the global GCB standard
  • Longest experience in design and manufacturing of circuit-breakers for industrial and power generation applications
  • Full Hitachi Energy support for suitability analysis and proper selection of GCB
  • Safe, reliable and economical solution

Brief performance data

Type VD4G-50 VD4G-63
Rated maximum voltage [kV] 15 15
Rated frequency [Hz] 50 / 60 50 / 60
Rated power frequency withstand voltage [kV] up to 38 up to 38
Rated lightning impulse withstand voltage [kV] up to 95 up to 95
Rated normal current [A] 3150 / 4000 (*) 3150 / 4000 (*)
Rated short-circuit breaking current [kA] 50 63

(*) on request 

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