In armoured cables, armouring must be removed before passing the cable through the CBCT to avoid induced e.m.f through the armour and the corresponding magnetizing current which may affect the performance of the current transformer. Aur agr enter ho gya armoured CBCT me to usko U turn le k waps la k earth krna pdta hai ... ua-cam.com/video/lq-MKKzNgWg/v-deo.html Watch this video after 7 .10 min
In case of HT cable earthing is done only at one end aur ye isliye karte hai kyuki ..agr dono end pe earthing karte hai to dono pit ka resistance different hota hai and kuch potential difference hoga ..jiski vajh se close loop banega aur leakage current close loop me ghumta Rhega .jiski vajah se heating hogi aur relay bhi malfunction kar skti hai ....so ek end pe earthing karne se leakage current direct earth hoga ....
Sir CBCT ki selection kis trah krty hain ?? jesy ham CT ki ratio ko dekh k lgaty hain.. Kia CBCT ka koi formula hai . Q k 1 CBCt har jaga to ni lga sakty koi 500A ka breaker koi 100 ka to kesy select kren CBCT ko
General range ki jo CBCT ati commonly use hoti h 50/1,100/1,200/1 aur kam range 40/1,25/1 ..Ab CBCT use ka karne ka main reason hota hai .. earth fault ya UNBALANCE ko detect karna..aur ye value boht jada nahi honi chahiye usse pehle hi system trip ho jana chahiye....mtlb CBCT kam rating ki hi mostly use hoti hai...ab depend karta ka ki ap apne system me kitna earth fault allow krte hai...for example 500/1 Ki CT lagi hai kisi motor me aur ap chahte hai ki 10 % hi earth fault setting rakhna chahte hai through CBCT to yaha apko 50/1 ki CBCT lagani hogi ..aur 20% rakhan chahate h to 100/1 ..mtlb Apke CT RATIO AUR EARTH FAULT SETTING PE DEPEND KARTA HAI CBCT RATING ..
An easy way to test CBCT ,you have to pass unbalance current through it .It can be passed by using single core cable and connecting halogen or any other load .Secondry of CBCt must be given to the tripping terminal of ELR relay (generally ELR relay min current setting is 30 mA) . So if setting is done minimum and current is passed through it then your ELR Must Trip .this is the best way of checking new CBCT.
@@electricalpracticalfunda suppose I have used yellow single phase lamp load...so 2 wire load, one wire entere in cbct hole to load and another neutral wire is outer side of cbct, that's way cbct tripping genrate or not sir
Yes I have done this experiment ...it will read unbalance when there is actual unbalance Condition....that's why we use CBCT to avoid nuisance tripping...
Very good. Thanks 🙏🙏🙏🙏
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Sir cbct power cable earthing kindly explain in details
In armoured cables, armouring must be removed before passing the cable through the CBCT to avoid induced e.m.f through the armour and the corresponding magnetizing current which may affect the performance of the current transformer.
Aur agr enter ho gya armoured CBCT me to usko U turn le k waps la k earth krna pdta hai ...
ua-cam.com/video/lq-MKKzNgWg/v-deo.html
Watch this video after 7 .10 min
Sir cbct ( in case of HT cable 11 kv induction motor) cable earthing done on feeder end. Or motor end or both end why?
In case of HT cable earthing is done only at one end aur ye isliye karte hai kyuki ..agr dono end pe earthing karte hai to dono pit ka resistance different hota hai and kuch potential difference hoga ..jiski vajh se close loop banega aur leakage current close loop me ghumta Rhega .jiski vajah se heating hogi aur relay bhi malfunction kar skti hai ....so ek end pe earthing karne se leakage current direct earth hoga ....
Is topic PE video se bhi explain krenge ...
Sir CBCT ki selection kis trah krty hain ?? jesy ham CT ki ratio ko dekh k lgaty hain..
Kia CBCT ka koi formula hai . Q k 1 CBCt har jaga to ni lga sakty koi 500A ka breaker koi 100 ka to kesy select kren CBCT ko
Sir kindly conform me
General range ki jo CBCT ati commonly use hoti h 50/1,100/1,200/1 aur kam range 40/1,25/1 ..Ab CBCT use ka karne ka main reason hota hai .. earth fault ya UNBALANCE ko detect karna..aur ye value boht jada nahi honi chahiye usse pehle hi system trip ho jana chahiye....mtlb CBCT kam rating ki hi mostly use hoti hai...ab depend karta ka ki ap apne system me kitna earth fault allow krte hai...for example 500/1 Ki CT lagi hai kisi motor me aur ap chahte hai ki 10 % hi earth fault setting rakhna chahte hai through CBCT to yaha apko 50/1 ki CBCT lagani hogi ..aur 20% rakhan chahate h to 100/1 ..mtlb Apke CT RATIO AUR EARTH FAULT SETTING PE DEPEND KARTA HAI CBCT RATING ..
how to test CBCT , is it possible to test NEW CBCT, how many ways CBCT test
An easy way to test CBCT ,you have to pass unbalance current through it .It can be passed by using single core cable and connecting halogen or any other load .Secondry of CBCt must be given to the tripping terminal of ELR relay (generally ELR relay min current setting is 30 mA) .
So if setting is done minimum and current is passed through it then your ELR Must Trip .this is the best way of checking new CBCT.
@@electricalpracticalfunda suppose I have used yellow single phase lamp load...so 2 wire load, one wire entere in cbct hole to load and another neutral wire is outer side of cbct, that's way cbct tripping genrate or not sir
Yes correct it will ,but ,if we ender both cores of cable/wire through cbct the it won't read unbalance .
@@electricalpracticalfunda thank you sir , I will try in my company this experiment if I have a chance
Yes I have done this experiment
...it will read unbalance when there is actual unbalance Condition....that's why we use CBCT to avoid nuisance tripping...
Mere do motor he usme ak motor 220 A jayada load leti he or ak motor 90A bahot Kam load leti he uska kya problem hoga sir.....
Dono ka KW kitna hai...aur application kaha use kar rahe hai...prob may due to mech load Jo connect hai aage ..agr motor rating same hai to...
Ct problem hota he?
Aur info chahiye can't say need rating...of both motors ,CT Ratio etc