Why we not use the impedance relay in protection of short transmission line ?
Answers were Sorted based on User's Feedback
Answer / pritish
in case of short transmission line, the protection due to arc resistance is the major factor. hence , the relay should be selected which is less affected to arc resistance. and according to R-X diagram of impedance and reactance relay, the area of reactance relay is more and it is less affected to arc resistance fault but impedance relay is moderately affected due to arc resistance. so reactance relay is used in a short transmission line.
for more clarification, please email to pritish.nath@gmail.com
Is This Answer Correct ? | 2 Yes | 1 No |
Answer / niket gupta
In the short transmission single to ground falling fault are occur 85% so when this fault occur then the resistance are changed so impedace are also changed and arc producing so we not use the impedance relay
Is This Answer Correct ? | 3 Yes | 3 No |
1. During Short circuit current Step and Touch potential increases.Step potential : It is the potential developed between the two feet on the ground of a man or animal when short circuit occurs. This results in flow of current in the body leads to electrical shockTouch potential: It is the potential that is developed between the ground and the body of the equipment when a person touches the body during fault condition. When operating personnel touch an electrical equipment during short circuit condition, fault current flows through the human body. This is defined as touch potential.Gravel/Stones in the substation is provided to reduce the step potential and touch potential when operators work on switch yard.2. Power Transformers installed in the substations will have oil as cooling and insulating medium. Oil leakage takes place during operation or when changing the oil in the transformer. This oil spillage which can catch fire is dangerous to the switchyard operation. So Stones/Gravel is provided to protect from fire when oil spillage takes place.3. Stones eliminate the growth of small weeds and plants inside the switch yard4. Improves yard working condition5. Provides protection from wild life and snakes.
Is This Answer Correct ? | 1 Yes | 1 No |
The impedance too small to be measured
Is This Answer Correct ? | 0 Yes | 1 No |
We have one 500KVA transformer. We have tested REF relay and commissioned. After one and half year, due to some ground fault in one of the DB circuit Transformer tripped by REF relay. What will be cause and remedy. Please advise?
how copper and aluminium wires or cables are choose for current rating? please provide copper and aluminium wire selection chart for different current rating ?
what is the basic principle of the alternator ????
why most of the induction are delta connected?
What is the name of process In VFD frequency are increase then voltage increase & frequency decrease then voltage decrease?
URGENT PLEASE//////////A WORK SHOP IS HAVING A 100 KVA TRANSFORMER 11KV/415 VOLTS, AND THE CONNECTED LOAD OF THE WORK SHOP IS 80 KW WITH INDUCTIVE LOADS, LIGHTING LOADS,ETC., HOW MANY EARTH ELECTRODES ARE NEEDED AND WHAT IS THE EARTH RESISTANCE OF EACH EARTH ELECTRODE AND COMBINED EARTH RESISTANCE in normal soil. AT 11 KV SIDE AND AT LT SIDE. HOW TO CALCULATE.
Is it posible to instal one more SMDB from the existing SMDB and is it practical.
Why Transistors are not used as switching devices?
Why we use Delta connection in the secondary side of a High Voltage transformer?
what is the purpose of interpose t/f in control and relay ckts?
how to calculate the settings for shaft ct protn in hydro generators
What is core CT & it's function?