Question { Alstom, 47118 }
What is the purpose of SOTF being used inspite of distance
Protection given?
Answer
During energisation of the line vt input is near to zero. at that time any fault happens in the line distance protection is not able to operate because vt is near to zero. So we are enabling the SOTF protection in the relay.
SOTF function: The relay will check if any fault happens during energisation with in the 20ms, if fault is presents the relay will operate as a simple O/C relay and its isolate the healthy section from faulty dection.
Current detection(A,B&C) and No Voltage detection(A,B&C)--> 20ms Delay ---> Trip