ABB's Switching Control Sentinel™ (SCS) device is designed for high-voltage circuit breakers.

Voltage and current transients generated during switching of high-voltage circuit breakers are of increasing concern to the electric utility industry. These concerns include both power quality issues for sensitive customer loads, as well as excessive stresses on power system equipment. The SCS functions to reduce these transients by enabling synchronous switching, sometimes referred to as point-on-wave switching. Synchronous switching is performed by a dedicated electronic device, which – upon receiving a close (or trip) command – delays the energization of the circuit breaker control coils by a few milliseconds such that current inception (or contact separation) coincides with a specific point on the AC wave that is known to reduce switching transients.

Synchronized closing applications include shunt capacitor banks, shunt reactors, transformers and transmission lines. In addition, synchronized opening optimizes the circuit breaker arcing time in reactor bank applications. The arcing time may be increased for the purpose of minimizing the probability of re-ignitions.

The SCS is also a Smart Grid capable device. The SCS achieves this by providing not only digital communication capabilities, but also microprocessor-based condition monitoring of the circuit breaker’s synchronous performance. This monitoring improves reliability by providing the utility feedback on the breakers synchronous performance. Detailed waveforms are stored for the last 20 operations in non-volatile flash memory. Smart Grid capability opens the door for utilities to participate in Title XIII of the Energy Independence and Security Act of 2007. Finally, as Smart Grid interoperability standards continue to evolve, the SCS firmware is designed to be flash-updated in the field via a serial port providing a simple upgrade path for the future.

Housed in a NEMA 1 enclosure, the SCS is installed as a modular component in the control cabinet of the circuit breaker and has been successfully tested for operation under extreme temperature and environmental conditions.

ABB