Overcurrent relays (CO, COD, COM, COQ, COV)

CO relays, a complete coordinated line, assure accurate and reliable primary or backup protection against phase or ground faults. They provide the back-bone of any protective relaying system, from generator to load.

COD current sensing relay

The COD current sensing relay is used to initiate switching or control functions upon a change in line current. It is equipped with independently adjustable high current and low current circuit closing contacts, and operates similar to a contact closing AC ammeter with inverse time delay.

COM overcurrent relays

The COM relays are designed for distribution feeder circuit applications where high speed overcurrent protection is required in conjunction with a reclosing relay to protect a lateral fuse to blow following that for permanent faults.

COQ Generator protection against unbalanced fault currents

The COQ relay is designed to protect turbine or engine driven generators from damage due to thermal heating caused by negative sequence currents which flow during unbalanced faults on the power on the power system.

COV voltage controlled overcurrent relay

The COV relay provides back-up protection for the generator and system from damage due to phase faults which are not cleared by primary relays and associated breakers.  

 Why ABB?

  • Long production life, ease of application and reliable protection
  • High quality design
  • 12 year warranty
  • Short lead times
  • Consistent on-time delivery
  • 24/7 customer support

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