Time Delay Limit of Over Current Relay for Maintaining Stability in Industrial Power Systems

산업용 전력계통의 안정도 유지를 위한 과전류계전기의 시간지연 한계

The industrial power distribution system is a radial system and therefore usually protected with time delayed over current relays (OCR's). Proper time dial settings are provided at the OCR's. Meanwhile, the systems, where synchronous generator, or synchronous motors, or large induction motors are operating, can not be protected with only OCR's with time grading. This paper presents a technical limit and a suitable range of time delay in applying OCR's to clearing faults in the industrial power systems for maintaining stability. Dynamic simulations are made to show them employing a real power systems of a large petro-chemical complex.