Hi, I've just got into my electrical engineering course and I need some

Hi,

I've just got into my electrical engineering course and I need some help with a question of mine here.

During a site visit, we were shown a main LT panel which has switchgears, ammeters and different kinds of relays and the distribution network from that panel. In the main LT panel I've noted down the current readings as Ir - 163A, Iy - 150A and Ib - 147A. The Line to Line voltage is 415 V at 50 Hz and Line to Neutral voltage is 230V at 50 Hz.

From the above details, how would I calculate the kVA rating of transformer? The primary side voltage of the transformer is 11 kV and the secondary side voltage is 415V and the frequency is 50 Hz.

Question Posted / confused.elec

2 Answers
3929 Views
I also Faced
E-Mail Answers

Answers were Sorted based on User's Feedback

Hi, I've just got into my electrical engineering course and I need some help with a question..

Answer / 7anoter4

Something is not correct. If VL_L=415 V then VL_N=240 V
[not 230 V] and then

both calculation results will be the same [no error].

Is This Answer Correct ?

2 Yes

0 No

Hi, I've just got into my electrical engineering course and I need some help with a question..

Answer / 7anoter4

The transformer actual load [apparent power] S=0.23*
(163+150+147)=105.8 kVA.

You may calculate approximately taken the average current
(163+150+147)/3=153.33 A and the formula sqr(3)
*0.415*153.33=110.2 kVA [4% error].

But this is not the rated power. The rated power and the
rated current have to be written on manufacturer rating
plates.

Is This Answer Correct ?

0 Yes

1 No

Post New Answer

More Electrical Engineering Interview Questions

I have a 380 KVA DG set. How can i find out 1. My Fuel Consumption per hr ? 2. Electricity produced in 1 Hr. ? 3. If load varies then how does it affect fuel consumption & electricity produced ? Please HELP !!! Really need an answer.

0 Answers

How to check the efficiency of the generator , air compressors.

1 Answers CIL,

Why the CT Secondary is rated as 5A generally?

2 Answers

what is RCBO?

1 Answers

What is the importance of RESONANCE

2 Answers

What is the Polarisation index value ? (pi value)and simple definition of polarisation index ?

15 Answers Essar,

why transformer rating in kva?