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Switching Control Sentinel (SCS)

For all ABB independent pole operated breakers

The Switching Control Sentinel (SCS) is a microprocessor-based control device, which enables synchronized closing or opening of independent pole operated (IPO) circuit breakers. Housed in a NEMA 1 enclosure, the SCS is installed as a modular component in the control cabinet of the circuit breaker at the factory.

Any model can be used for any synchronous closing or opening application by means of configuration and external wiring. A bypass circuit, providing ganged breaker operation in case of loss of DC power, can be enabled or disabled via an external jumper.

The current firmware version is 3.55, Build 14. 


  • Same firmware and hardware supports synchronous opening or synchronous closing of grounded/ungrounded capacitor bank energization.
  • Firmware upgrades are possible in the field via serial port extending life of product via future upgrades
  • No EPROM changes are required
  • The SCS can be powered down without data loss
  • Both settings and event data are stored in non-volatile Flash memory
  • Battery-free design
  • A real-time clock is powered by a gold capacitor while DC power is off
  • Automatic tracking of the delay between arcing and auxiliary contact operations for synchronous opening (patent pending)
  • Detection of wiring errors through phasor calculation (patent pending)

Why ABB?

  • Controlled point-on-wave switching is a very effective way of reducing switching transients and enhancing circuit breaker performance
  • Synchronized closing reduces transient over-voltages and currents associated with switching operations of shunt capacitor banks and shunt reactors
  • Synchronized opening allows for optimization of the circuit breaker arcing time. The arcing time may be increased with the purpose of minimizing the probability of re-ignitions
  • Reduced interrupter wear

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