What is Relay Time?
Answer: Relay time is the interval between the occurrence of the fault and the closure of the relay contacts is called relay time.
What is fault clearance time?
Answer: When the fault occurs relay operates and close the trip coils and circuit breaker operates and open the contacts subsequently and fault is cleared. Therefore fault clearance time is the sum of relay operating time and circuit breaker operating time and clearing the fault
What is Reach?
Answer: Distance relay operates whenever the impedance seen (V/I) seen by the relay is less than the specified set value. This impedance or corresponding distance is known as reach of the relay. Reach is the limiting distance covered by the relay for protection of line. Faults beyond the distance (reach of the relay) relay will not operate and should be covered by the other relay.
What are the fundamental elements of relay?
Answer: Basic fundamental elements of the relay are:
- Sensing element: It is the measuring element measures the actuating quantity. Actuating quantity is change in current in case of over current relay
- Comparing element: It compares the actuating quantity with the relay pre-setting of the relay
- Control element: On pick up of the relay control element carryout the final switching operations such as closing the circuit to operate the circuit breaker
What are the good features of protective relaying?
Answer: Some of the good features for protective relaying are: Reliability, Selectivity, Sensitivity, Simplicity, Speed and economy
Some of the causes for relay failures?
Answer: Primary reason for relay failure to operate during faults are wrong settings, bad contacts and open circuit in the relay coil.
1 comment:
Don't find fault, find a remedy. See the link below for more info.
#fault
www.ufgop.org
Post a Comment