Power Systems Protection Power Quality and Substation Automation
Covering concepts that are important and useful to the engineer, scientist and technician independent of discipline.
The object division of the Substation Automation system consists of Intelligent Electronic Devices (IEDs), modern, 3rd generation microprocessor based relays and/or Remote Terminal Units (RTUs). (PLCs also continue to play an important role in some systems.) They receive analog inputs from the Current Transformers (CTs), Voltage Transformers (VTs) and transducers in the various switchgear panels, as well as digital inputs from auxiliary contacts, other field devices or IEDs, or the SCADA Master. They are able to perform complex logical and mathematical calculations and provide an output either to the SCADA Master, other field instruments or IEDs, or back to the switchgear to perform some command, for example open a circuit breaker.