How to know the VA rating of a transformer
Hello to all
I am an electrical engineer and in an interview I was asked to tell the MVA rating of a transformer of few KV , and nothing was given means neither the power factor and nor the current , so I want to ask you people is there any way to determine the MVA rating of the transformer from the KV or viceversa.
Please tell me with an example if possible.
Thank you
I am an electrical engineer and in an interview I was asked to tell the MVA rating of a transformer of few KV , and nothing was given means neither the power factor and nor the current , so I want to ask you people is there any way to determine the MVA rating of the transformer from the KV or viceversa.
Please tell me with an example if possible.
Thank you
Replies

u_know_whoAs far as i am concerned in XFR (transformer) both KV and MVA rating are mentioned. Both of them are essential because you can calculate rated current, rated impedence etc from this two value. So KV and MVA rating are independent variable. I don't know if there is practical function between them.
May be in practice there is some combination of this two. Which requires practical knowledge not mathematical issue. 
Arpnot possible to tell the exact VA rating of the transformer given.
but if given the Voltage then u can decide whether it is coming inthe distribution or transmission or which range. then u can give an approx estimation of the KVA rating. ok 
piyushpandey
hello arpArpnot possible to tell the exact VA rating of the transformer given.
but if given the Voltage then u can decide whether it is coming inthe distribution or transmission or which range. then u can give an approx estimation of the KVA rating. ok
first of all thanks for your reply .
Actually I meant the same that how can you estimate the approximate value of the VA as ofcourse it is impossible to get the exact value of VA from the value of just of voltage and not the current.
So can you show this with an example, please.
Piyush Pandey 
ArpAs an example, if the voltage rating of two sides are like 11 kv and 220 kv indicates it is a generating transformer so its rating is someewhat in range 100to 200 MVA, if 15.75 kv then 300 MVA and if 21 kv to 220 kv then can be 600900 MVA even.
if rating are 11 kv and 33 kv indicate its rating around 20 MVA.
if unit auxillary transformer (6.6/433) then should be around 24 MVA
if distribution one then should be around 25KVA to 10 MVA usually 110 MVA.
data taken from my internships done
if any furthur query u have, post here. 
Alienator
whats the math behind it? bro...ArpAs an example, if the voltage rating of two sides are like 11 kv and 220 kv indicates it is a generating transformer so its rating is someewhat in range 100to 200 MVA, if 15.75 kv then 300 MVA and if 21 kv to 220 kv then can be 600900 MVA even.
if rating are 11 kv and 33 kv indicate its rating around 20 MVA.
if unit auxillary transformer (6.6/433) then should be around 24 MVA
if distribution one then should be around 25KVA to 10 MVA usually 110 MVA.
data taken from my internships done
if any furthur query u have, post here. 
Arpno math behind it just logic
what i know is the line voltage rating of the different rating alternators. from there u can know the kva rating of transformer if know the line voltage.
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