Transformers Levels

No the short circuit level of transformer can not be fix with regards system sc level. yes the short circuit level of transformer can be fix with regards system sc level in case if the system is connected with secondry side of T/F then we can fix T/F sc level with regards to whole system SC level.

We devide the electrical system in two parts one is primary part and other is backup For example a fault occure in electrical system in this case first primary part of system work and trip or turn off the system if primary part of system did not work due to any reason then backup part of electrical system work and turn off the circuit. If you examine the electrical system of a house then you see that the rating of short circuit current of C.B. (circuit Breaker) of main DB is greater than SC level of sub main DB.

If u see the formula of short circuit current then u see that short circuit current depends upon the KVA of the system. SO ______________

U examine

Dear Sir,

Transformer shortcircuit current level depends on the rating of transformer and its percentage of impedence(z%).The maximum shortcircuit that can flow during shorcircuit current (Isc) in the transformer is given by equation if we neglect system impedence

Isc=100 x I rated current of transformer/ Percentage of impedence(z%)---(1)

At the outset SCL of transformer has no bearing on system short circuit level.But it has bearing to the extent that it will reduce the transformer shortcircuit current depending upon system impedence (which depends on system Shortcircuit level

Zs- v x v/ScL of system) as calculated as per equation-1 above.

V.Ambarani

Dear Sir,

The Short Circuit Current of Bus bar on the HV & LV side of the transformer as well the transformer Short Circuit Current varies depending on system requirement.

Best Regards,

N.Suresh