If you have a transformer with let's say 3x 400 amp fuses protecting its LV outgoing cables how do I calculate its KVA? Do you just time amps by the single phase voltage or by the volts across 2 phases
You can make a rough estimation by doing the following calculation:
First of all the following information should be available.
a) Type of LV fuse (HRC/ Wired/Glass fuse)
b) Voltage rating of LV. If the same is not available you can take the working voltage of LV winding as voltage rating. If this is not possible then see the fuse, generally they also have rated voltage printed on it.
c) Percentage impedance of transformer
Calculation:
In general, the fuses have a rating between 125% to 250% of the rated current of the LV winding. If you want a conservative estimation of transformer VA, you may assume that the fuse you have in hand is 250% of rating. Hence rated current can be estimated as 400/2.5 A. With voltage data available you can calculate the VA rating using standard formula.
Please note this is a rough estimation as a number of factors such as whether the transformer has tap changer or has multiple windings etc shall affect the calculation.
You can make a rough estimation by doing the following calculation:
First of all the following information should be available.
a) Type of LV fuse (HRC/ Wired/Glass fuse)
b) Voltage rating of LV. If the same is not available you can take the working voltage of LV winding as voltage rating. If this is not possible then see the fuse, generally they also have rated voltage printed on it.
c) Percentage impedance of transformer
Calculation:
In general, the fuses have a rating between 125% to 250% of the rated current of the LV winding. If you want a conservative estimation of transformer VA, you may assume that the fuse you have in hand is 250% of rating. Hence rated current can be estimated as 400/2.5 A. With voltage data available you can calculate the VA rating using standard formula.
Please note this is a rough estimation as a number of factors such as whether the transformer has tap changer or has multiple windings etc shall affect the calculation.
