Transformer Circuit breaker and Fuse size Calculation

[@ShahulHameed-ic7tn]

very useful info regarding electrical field.

[@Rashid-iqubal]

Thanks and keep watching

[@nazmulkabir2481]

Very Very Informative and helpful

[@Rashid-iqubal]

Thanks for watching

[@mohammedirzath2788]

can you tell me why your following NEC for breaker calc

[@vipinsoni8437]

Please make a video for calculation of breaker making & breaking current.

[@deepakmuyal4096]

Kindly upload substation design videos

[@Rashid-iqubal]

Will upload soon

[@vinodkumarprajapati5182]

Very good

[@Rashid-iqubal]

Thanks 🙏🏽

[@manzoorkhan5246]

For sizing breaker, contactor and cables which standard you normally use?

[@Rashid-iqubal]

@@manzoorkhan5246 NEC

[@manzoorkhan5246]

@@Rashid-iqubal please explain it further or mention any specific code like 23567

[@seanakiiki7670]

Great, thxu

[@Rashid-iqubal]

Thanks for watching...

[@maikanataucoko5888]

For the 2nd example, is there a reason why you used P= 1600KVA for the secondary current? or was that a mistake?

[@Rashid-iqubal]

It should be 1500 kva, typo error

[@NomanQudrat-u2p]

Brother very nice

[@Rashid-iqubal]

Thanks 🙏🏽

[@kaleemahmad6573]

Why you did not consider the fault current of primary side of HT 33 KV brraker rating will come above 800 amp if you will see the fault current

[@Rashid-iqubal]

Actually In this video I explained CB current rating as per load.. For fault current calculation we should divide full load current (Is) / impedance. Short circuit current always higher than normal current rating of breaker. Every circuit breaker has two types of rating that is current rating and short circuit rating (ka) As per my first example we have selected 630amp circuit breaker and its short circuit current would be 52.49/4.71% =1.1Ka I will make another video which cover all safety protection. Thanks for watching

[@brajeshtripathy7599]

Please make a video on Transformer, DG sets, UPS selection in details.

[@Rashid-iqubal]

Sure my next video will be on Generator and transformer. Thanks for your suggestion

[@noelfaithfulkari2857]

thank you sir for your amazing explanations. any video on transformer sizing??

[@Rashid-iqubal]

@@noelfaithfulkari2857 thanks for watching, my next video will be on transformer size calculation method.

[@souravhajra1645]

What do we use to select a circuit breaker, full load current value or short circuit current value? Please clarify, i am so confused..

[@Rashid-iqubal]

For circuit breaker calculation you need both full load current and short circuit current. Through full load current you can find out the rating of breaker. If current exceed then full load current in any circumstances like over load or short circuit, breaker will be trip. While short circuit current work when huge amount of current flow like 100 or thousand times more then full load current then breaker trip immediately in few mili second. It will protect system from fire as well as breaker it self. So if you purchase circuit breaker you need both rating. Eg 1000A ACB with 50KA short circuit current in 1sec. Or 36KA in 3sec. Thats mean circuit breaker can tolerate 50Ka current upto 1 second. Hope you understand.

[@souravhajra1645]

Thanks alot, understood completely sir..

[@nategreene45]

What if it is a step-up transformer? 480v, 3ph to 4,160v, 3ph. Say impedance is 5%. Am I using 600% factor from the table to size the circuit breaker on the primary (480v) side?

[@narayanmanna6532]

Please make a video on LT panel incomer, bus coupler & outgoing feeder ACB , MCB & MCCB size selection in details please.

[@Rashid-iqubal]

Sure, i will cover all these topic

[@AfrozAlam975]

U explained very well and your voice is so energetic and crystal clear. May i request to please earthing wire and pit calculation pe ek video banayen. Like high rise sky scrappers, hospital and residential building me earthing and selection of bare copper wire clams and pit etc

[@Rashid-iqubal]

Thanks, sure i will upload soon..

[@salmananwar8370]

dear i follow NEC calculation, but not in all cases , you have given exp of 1000 kva which has currnt capacity 1440 amps and we can consider 1600 amps which is already at next size then why we go on 2000 amps 2 times higher than trafo size. we know when we on transformer , inrush current happens but if we size the breaker as per curve characterstic then we don need to go on higher size which is technically and economically not good.

[@Rashid-iqubal]

Brother i request you to please watch this video carefully, for 1000KVA full load current is 1391.24 amp and as per NEC standard we must consider 125% (125% of FLC to ensure it can handle both the regular operating current and the inrush current) then it become 1739amp and the next available size of breaker will be 2000 amp.

[@salmananwar8370]

@@Rashid-iqubal dear I appreciate your effort but adding 125 percent on line current secondary getting oversize more than transformer is unnecessary requirement. 1000 kva line current is 1440 amps available size z 1600 amps ACB in which breaker curve can bear the inrush current , that's m not talking in the Air that is my practical exposure I have done projects and proposed 1600 amps ACB that's under operational , running smoothly without any tripping. I follow nec alot but I have concerned on NEC 450.3A . Cause your design standard not only based on NEC practical exposure also does matter , when 1600 amps ACB characteristics curve offers over current protection then why do I go on 2009 amps.

[@salmananwar8370]

@@Rashid-iqubal recent I have completed data center project in ryadh in which all trafo's are dry type as per specs dry type generate huge inrush current, I installed 4 trafo's of 3150 where I proposed 5000 amps ACB accordingly all substation are operational and working smoothly.

[@Rashid-iqubal]

@@salmananwar8370based on your country standard or design it may happen.. i also worked in saudi and Qatar, depends on requirements and project budget we can negotiate. However for 1000 kva transformer i always used 2000amp ACB and very rarely i see 1600amp ACB. I am not saying that 1600amp is not correct. Moreover you worked in Saudi, in middle east they never compromise with safety and standards. And my calculation is totally based on NEC standard.. hope you understand dear..

[@manmohandhir9117]

In India we follow iec rules and not nec rules.You can consult any state electricity authority and you will discover that proper fuse size for this transformer will be 80 A.CB rating for secondary will of course be 1.25 times secondary current.

[@Ab_multimedia24]

Formula wrong kva how to write

[@Rashid-iqubal]

@@Ab_multimedia24 what wrong ???