Sir I am Farhan from Karachi water & sewerage bord recently hamara HT< penal upgrade howy he is me incoming VCB me fannox ki rely lagai Gai he us rely ki setting k bary me Kuch bataen
Voltage is considered for polarisation I.e. for determination of direction in case of directional over current relay. Voltage is not considered for grading margin. If you see non directional relay, then voltage is not required.
Sir Take an Example where utility gives only let say 550mS for max fault with SI curve and you got 3 steps coordination down stream. I face a problem when curve goes to minimum definite time and that time does not grade over full range. Any solutions for that.
This is the problem with over current relay, you can’t coordinate with all conditions because over current protection depends upon source impedance. Some numerical relay gives the option to create custom curve (r.g. NR OCS 902/931), in some relays have the option to set minimum time of operation for IDMT or we can set additional time delay ( e.g. ABB Make Relays)….. However the coordination is difficult in complex networks.
Really Sir, great teaching.
Excellent explanation... Big and prolonged doubt is almost clear....
Glad it helped
Excellent explanation. Today, I got relay coordination perfectly.
Thank You
Excellent video ❤
Thank You
Thank you very much sir.
Most welcome
Very good. Thanks Sir 🙏
Nice presentation, indeed. Could you please tell me about the earth fault (50N/51N) protection setting?
thanks sir for your generosity
Thank You
Thank you sir
You’re welcome
Request to please make some conceptual videos on tertiary winding. Love from Pakistan. Doing excellent job sir
Sir I am Farhan from Karachi water & sewerage bord recently hamara HT< penal upgrade howy he is me incoming VCB me fannox ki rely lagai Gai he us rely ki setting k bary me Kuch bataen
Sir how to calculate fault current?. In system we see lots of variation in fault current recorded by relay.
Sir please upload pdf also if possible, that will be so helpful... Anyway your videos are great
Sir,
If we measure value on behalf of current then why do we consider voltage in grading margin?
Voltage is considered for polarisation I.e. for determination of direction in case of directional over current relay. Voltage is not considered for grading margin. If you see non directional relay, then voltage is not required.
what is relay reset time in protection coordination not clear sir.
Sir Take an Example where utility gives only let say 550mS for max fault with SI curve and you got 3 steps coordination down stream. I face a problem when curve goes to minimum definite time and that time does not grade over full range. Any solutions for that.
This is the problem with over current relay, you can’t coordinate with all conditions because over current protection depends upon source impedance. Some numerical relay gives the option to create custom curve (r.g. NR OCS 902/931), in some relays have the option to set minimum time of operation for IDMT or we can set additional time delay ( e.g. ABB Make Relays)….. However the coordination is difficult in complex networks.
sir TMS kia ha
1st view
😊 Thank You