Transformer Circuit breaker and Fuse sizing Calculation. Learn how to calculate proper size of VCB and Fuse for Transformer. #electricalengineering #rashidiqubal
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.
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
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
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?
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.
