11kV/433V Transformer

If it is so it is rated for optimum in considering economic,protection and many other facts. Can you calculate rated ampere for transformer having more than 2MVA in its low voltage side?

Not true.The restriction of maximum capacity of 11 kv/433 V transformer depends upon the available maximum rating of LV side Air Circuit Breakers (ACB).

These days ACBs of ratings as high as 6300 A are available.This can meet the requirement of maximum transformer capacity upto 4.5 MVA.

However, the capacity of the transformer is normally selected depending upon the Maximum demand of the substation at the concerned load center.

But then what will be fault current from a 4.5MVA Trabsformer? Can your 6300A ACB break it safely?

Certainly.

You may see ABB's catalogue for Emax type low voltage ACB model No.E6H/f ,which indicates the rated ultimate breaking capacity under short circuit (Icu) as 100 kA at all low voltages including 415 volts . Fault current from a 4.5 MVA transformer will be less than the above value.

Economics are a ruling factor. As spradhad said ACB's can be rated up to 6300A but then you have the problem of fault currents on the bus bars and all ancillary equipment related to the system. Multiple lower rated units are a more viable (and safer) option.

Multiple lower rated units are a more viable (and safer) option.

As well as being easier to transport on standard roads which have size, weight and height restrictions.

Is it like that or not?.

NOT LIKE THAT.

If it is like that then what is the reason?

QUESTION NOT APPLICABLE.

Is there any reason related to voltage range?

QUESTION NOT APPLICABLE.

Please help me...........

WHAT HELP DO YOU NEED?

this may also help you understand the subject . . .

http://www04.abb.com/global/seitp/seitp202.nsf/0/7b44883d7fae1d23c125761f004e1194/$file/Vol.2.pdf