Extending SCADA systems to provide cost effective distribution switchgear condition monitoring

The authors describe the design and application of a microprocessor controlled disturbance recorder (MCDR) which can be interfaced to the remote terminal unit (RTU) of a SCADA system. The recorder stores the instantaneous voltage and current values, and status of the circuit breaker auxiliary contacts, at a rate sufficient to allow it to perform a post-fault computation of the amplitude and duration of the arc current(s) in each phase of the circuit breaker. These computed values are then communicated to the RTU from where they can be accessed by the central hardware of the SCADA network