Hi, Thanks you very much for sharing your knowledge. I request to clarify one doubt. Usually 51N & 51G is setting at 10 to 30%. In video it is setting above 100%.
Thanks for nicely explaining the method of earth fault protection and coordination. Can you please post a similar video pertaining to a case of HV system neutral Earthed through Neutral grounding transformer.
Very nice explanation. One Clarification. I have existing settings from the Client. I am adding new switchgear and MCC in to the existing network. How to start the relay coordination study? Should be from upstream settings (from the client) to downstream or downstream to upstream?
you are considering 50N(HV1) Is 5% of 400A. It is very less .it may trip during charging of 6.6/.433kV Transformer due to Inrush current.Because it DMT not IDMT. so you may increase the pickup value to 80% of NGR Rating
i have a video on time gradation. watch that video. then watch this video you will understand. and regarding auto recloser as per i am concerned it is a feature of circuit breaker duty cycle. CIRCUIT breaker has a duty cycle of open and close sequence. for circuit breaker having auto recloser scheme the breaker closes after a delay of 0.3 sec. then it checks if there is still a fault. then again it opens. you do not have to make any setting. it is inherent feature of breaker......
Good evening sir thanks for your video I have question I have O/C relay In=300/1 Is=1.2In Time 500 msec How can I calculate the trip time and accept the relay and saying is agood ?
33 kV system shall be solidly earthed. So you can increase the pick up setting. However prior to increasing the pickup check the system throughly if there is really anybearth fault or not.
Hello sir the video was really good but i have some doubts as follows: 1. When to use 50 and when to use 51 relay? 2. What happens when there is a fault above bus 1? 3. How can we calculate the transformer withstand capability as we need to coordinate the relays accordingly?
1. use 50 for the end feeder at any voltage like capacitor, motor transformer. say a 6.6/0.433 kv transformer is an end feeder at 6.6 kv level. after that it transfers power at 0.433kv level . 2. for that upstream Protection will work. these protections are arranged in sequence to give serial backup to each other. 3. transformer withstand capability is specified. in general transformer can with stand fault current if the secondary is bolted short circuit with full rated voltage at primary for 2 second. transformer designs are made like that
Pls check your earth fault current calculations for 433 V system. For solidly grounded system (considering 1 ohm earth pit resistance) = (433 V/ 1.732 )/ Earth resistance (1ohm) = 250 Amps. Correct me if I am wrong.
No it is wrong. For solidly earth system earth fault current will be mostly same with phase fault current because the earthing conductors will be interconnected. 1 ohm resistance is conductor to ground resistance.
I mixed up with NGR calculation. So your observation is wrong. As the current through soil is only 250A so GPR will be 250V. Which will be well within tolerable limit. That is why for LT system we do not need to check GPR criteria.
Hello, Can you help me with the cable sizing for the NGR ground cable and neutral cable? 1.) Does the ground and neutral cable for NGR to be sized as per 400A or it should can sized lower as earth fault relay will operate at 10% of NGR rating. Please help.
@@electricaltechnologyandind5335 thanks for ur reply...but in normal condition there will be no current flow in nuetral of trfr. So settings with 10% of ct current is enough for 51NS relay operation.... and at normal condition trfr lv side the resultant current for 51NLV will be zero...so any small current flow during fault can operate 51LV say 10% of ct rating as the resultant current will not be zero... So I want to say that 10% of ct current is enough for EF pickup as we used to provide settings for EF in such a way...
if 9MW, 11kv generator connected to Grid with continours synchronized condition, .... so Generator NGR keep close condition or not...... can any one explain me......
See generally generators are connected to grid via a generator transformer which has a vector group of Yd1 or Yd11. So presence of the delta winding isolates thr zero sequence network from getting paralleled. So if you have GT with one winding delta you can comfortably close the NGR
Hallo i am lao can speak english alitebit can you sent me a lession flie becasuse i don't know how to download load file,i need relay protection lession flie,
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Thank you for your very informative video
Just amazing 👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻
Very good description & useful for the commissioning engineers !
Hi, Thanks you very much for sharing your knowledge. I request to clarify one doubt. Usually 51N & 51G is setting at 10 to 30%. In video it is setting above 100%.
Nice explanation. Understood it very clearly. Thank you Sir.
Nyc explanation with practical solutions...great sir.
Plz make a vdo on rotor earthfault relay
you are my guru now :)
Thank you very much for this lecture
Thanks for nicely explaining the method of earth fault protection and coordination. Can you please post a similar video pertaining to a case of HV system neutral Earthed through Neutral grounding transformer.
Very nice explanation. One Clarification. I have existing settings from the Client. I am adding new switchgear and MCC in to the existing network. How to start the relay coordination study? Should be from upstream settings (from the client) to downstream or downstream to upstream?
Thanks a lot. Merci beaucoup
Thank you sir .... please make check synchronised relay i.e 25M topic lectures.
Excellent
Thanks Sir
you are considering 50N(HV1) Is 5% of 400A. It is very less .it may trip during charging of 6.6/.433kV Transformer due to Inrush current.Because it DMT not IDMT. so you may increase the pickup value to 80% of NGR Rating
Pls teach about power generation design
Good video
Sir plz guide how to do settings of auto recloser..
And there coordination with feeder and incomers
i have a video on time gradation. watch that video. then watch this video you will understand.
and regarding auto recloser as per i am concerned it is a feature of circuit breaker duty cycle. CIRCUIT breaker has a duty cycle of open and close sequence. for circuit breaker having auto recloser scheme the breaker closes after a delay of 0.3 sec. then it checks if there is still a fault. then again it opens. you do not have to make any setting. it is inherent feature of breaker......
Nice explained sir. Sir, How do you select the feeder wish curves?
Hi Can You please make a video on motor protection setting considering numerical relays. I desperately need it
🌟🌟🌟🌟🌟
Please make your video in hindi. It’s humble request.
Good evening sir
thanks for your video
I have question
I have O/C relay
In=300/1
Is=1.2In
Time 500 msec
How can I calculate the trip time and accept the relay and saying is agood ?
Hi sir..please explain about schneider VIP 45 relay.my system tripping due to earth fault..setting at 7A,0.77msec,on 33kv RMU
33 kV system shall be solidly earthed. So you can increase the pick up setting. However prior to increasing the pickup check the system throughly if there is really anybearth fault or not.
How to calculate for 50 overcurrent protection in trf
Hhindi mnhi h ka
Hello sir the video was really good but i have some doubts as follows:
1. When to use 50 and when to use 51 relay?
2. What happens when there is a fault above bus 1?
3. How can we calculate the transformer withstand capability as we need to coordinate the relays accordingly?
1. use 50 for the end feeder at any voltage like capacitor, motor transformer. say a 6.6/0.433 kv transformer is an end feeder at 6.6 kv level. after that it transfers power at 0.433kv level .
2. for that upstream Protection will work. these protections are arranged in sequence to give serial backup to each other.
3. transformer withstand capability is specified. in general transformer can with stand fault current if the secondary is bolted short circuit with full rated voltage at primary for 2 second. transformer designs are made like that
Thank you very much sir
Hello, very nice lecture.. thank you. Please, is it possible to do another similar video with relays 67N and 50/51/51N/50N together? In advance thanks
I shall try
@@electricaltechnologyandind5335 hello,... Thank you very much
Are you an Protection Engineer??
I have experience and interest on the subject.
Pls check your earth fault current calculations for 433 V system. For solidly grounded system (considering 1 ohm earth pit resistance) = (433 V/ 1.732 )/ Earth resistance (1ohm) = 250 Amps. Correct me if I am wrong.
No it is wrong. For solidly earth system earth fault current will be mostly same with phase fault current because the earthing conductors will be interconnected. 1 ohm resistance is conductor to ground resistance.
@@electricaltechnologyandind5335 pls put some disclaimer or correct this video. Else somebody will learn it in wrong way.
No whatever you are saying is current to ground. But that may not be the earth fault current always.
I mixed up with NGR calculation. So your observation is wrong. As the current through soil is only 250A so GPR will be 250V. Which will be well within tolerable limit. That is why for LT system we do not need to check GPR criteria.
Hello, Can you help me with the cable sizing for the NGR ground cable and neutral cable?
1.) Does the ground and neutral cable for NGR to be sized as per 400A or it should can sized lower as earth fault relay will operate at 10% of NGR rating. Please help.
For 400A
Why u have selected 120 perc of full load current for 51NLV and 51NS why not 5 or 10 perc like upper relays...
Since the lv neutral is solidly earthed so we can take 120 percent of flc as pickup
@@electricaltechnologyandind5335 thanks for ur reply...but in normal condition there will be no current flow in nuetral of trfr. So settings with 10% of ct current is enough for 51NS relay operation.... and at normal condition trfr lv side the resultant current for 51NLV will be zero...so any small current flow during fault can operate 51LV say 10% of ct rating as the resultant current will not be zero...
So I want to say that 10% of ct current is enough for EF pickup as we used to provide settings for EF in such a way...
Yes you can do that. Minimum pick up setting for earth fault is always recommended
Correct sir. 120% is too high and it might not trip during ground arcing fault
Yes right... if we keep it at 120% then whats the use of having a separate 51N. It is then as good as 51 with 120%.
if 9MW, 11kv generator connected to Grid with continours synchronized condition, .... so Generator NGR keep close condition or not...... can any one explain me......
See generally generators are connected to grid via a generator transformer which has a vector group of Yd1 or Yd11. So presence of the delta winding isolates thr zero sequence network from getting paralleled. So if you have GT with one winding delta you can comfortably close the NGR
Hallo i am lao can speak english alitebit can you sent me a lession flie becasuse i don't know how to download load file,i need relay protection lession flie,
Hindi please sir
Hindime bhejona