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Medium-Voltage Vacuum Generator Circuit Breakers, Drawout Type GMSG-GCB

For 10 MW to 80 MW Machines

Features and Benefits


Drawout type generator circuit breakers for use in type GM-SG metal-clad switchgear are available. These circuit breakers are derived from the same type 3AH3 family of circuit breaker operating mechanisms as our standard non-generator circuit breakers. The basic design of the circuit breakers is the same, making maintenance and operation of the generator circuit breakers the same as for non-generator circuit breakers. This means that there is no incremental or additional training needed for your maintenance or operational personnel. The type GMSG-GCB generator circuit breakers exploit the long history of successful service provided by the entire type 3A (including types 3AF and 3AH operators) family of vacuum circuit breakers.

These generator circuit breakers fully conform to the requirements for generator circuit breakers as specified in IEEE Std C37.013, "IEEE Standard for AC High Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis."

Medium-Voltage Vacuum Generator Circuit Breakers, Drawout Type GMSG-GCB for Small Machines 10 MW to 80 MW


  • One-high or two-high drawout construction

  • Up to 50 full-fault interruptions

  • Front accessible circuit breaker operating mechanism for ease of maintenance

  • Closed door racking

  • Floor rollout circuit breaker in lower cell without a dolly

  • Visible secondary disconnect

  • Circuit breaker ships inside of cell, thus reducing installation cost and potential transit damage

  • Pair with Siemens protective relays to provide complete generator protection

  • Drawout type GMSG-GCB vacuum generator circuit breaker with type 3AH3 operating mechanism

  • Uses the latest developments in vacuum interrupter technology

  • Highly reliable vacuum interrupters - MTTF over 57,000 years

  • Common type 3AH3 operator platform

  • Over 60,000 type 3AH3 operators produced since 1998

  • Generator circuit breakers tested to IEEE C37.013/C37.013a

  • 10,000 operations to overhaul

  • Three-cycle interrupting time (optional)

  • Meets or exceeds the latest ANSI, IEEE and NEMA standards

  • UL or C-UL Listing available

  • Available in lineups of conventional type GM-SG switchgear, indoor or outdoor.

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