Size of LV cables of a Transformer 2

[paulcolesec]

What determines the size of LV cables on a Transformer ?
Say on a 11000/415 volt 800 kVA, is it the conected load or the the actual kVA Rating?

 

[dydt]

i always size the cable on the LV side of the transformer based on KVA rating and not on the connected load..

i always consider the future load growth which will be a problem if you size the cable on the present connected load only...


dydt

 

[paulcolesec]

Dear dydt,

Many thanks for that answer, it was the answer I was hoping for.
I have read several books but cannot find a hard and fast answer to my question.
I was not sure if short circuit current came into the equation, but I shall use your solution.

Again many thanks,

Paul

 

[RavenJoe]

Paul,
I aggree with DYDT. Size to KVA rating.

 

[electricpete]

the short circuit rating will come into play when you select the protection settings.

 

[busbar]

Consistent with views already stated, why would you want to restrict transformer loading via secondary bus/conductor sizing? In most cases, that would seem like a false sense of economy.

 

[ADN]

Hi,

Yep KVA it is!

Just keep in mind that laying conditions will affect current carrying capacity.

best of luck..

ADN

 

[Wirenut]

Since we are on the subject: What protects the cable on the secondary side??? Would it be the breaker on the HV side??? Wirenut

 

[gordonl]

The main breaker or fuse your terminating your low voltage cable at, for overloads, and the primary and secondary protection for short circuits.