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Disconnecting Circuit Breaker (DCB) with Fiber Optic Current Sensor (FOCS) 420 - 550 kV for Digital substations

A smart grid ready solution for use with IEC 61850-9-2LE process bus communication

The DCB with FOCS includes three functions in one device: measurement, interruption and isolation. FOCS is a Fiber Optic Current Sensor that replaces the conventional current transformer for current measurement. Integrating the FOCS into a DCB (Disconnecting Circuit Breaker) provides the following advantages:

  • Short-circuit performance at twice the industry standard 
  • Faster installation times; plug and play
  • One FOCS replaces many CT cores, simplifying design and engineering substations
  • Lower environmental impact 
  • More intelligent protection and control due to smart process bus interface  

A Disconnecting Circuit Breaker (DCB) provides the functions of a circuit breaker and a disconnector combined in a single unit. Read more


  • Smart grid enabled as per IEC 61850-9-2LE
  • Line, transformer, reactor and capacitor switching 
  • Switching for harmonic filters 
  • Suitable for industry applications due to low space requirements and high reliability

Why Hitachi Energy?

  • Only solution with optical current measurement integrated in a disconnecting circuit breaker
  • World leader in optical current measurement systems 
  • Fully redundant, hot swappable plug and play solution 
  • Local and global Hitachi Energy industry and application support 
  • Global service organization, local everywhere

Brief performance data

DCB with FOCS    
Rated voltage kV 420 - 550 
Frequency Hz 50 - 60
Rated current A 4000
Rated breaking current kA 63
Rated power frequency  Hz 50/60
Ambient temperature C - 40 - +50
Measurement class TPE 5
power plant engineer for substation
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