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
4016 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

where is the need for short circuit test for 3 see is required and why? can you explain in brief with application

0 Answers

What about Reactive power.and role of that one?

7 Answers

What is force on parallel conductors ?

0 Answers

how to calculate the knee point voltage of current transformer?

2 Answers

What is the meaning of maximum demand

21 Answers MN Dastur,

why it is unable to birds to be on a 220kV 0r 132 kv lines like on 33kV and 11kV lines?

4 Answers MSETCL Maharashtra State Electricity Transmission Co Ltd,

When measuring the Insulation resistance of a motor winding (winding to earth) using a megger meter, Applied voltage(1000V) was automatically reduced to 500V. and the measured insulation resistance values are also very low (in Kohm range) Can anyone give me a reason???

3 Answers

What is the difference between lubricating oil and insulating Oil?

4 Answers Orchid,

What is OLTC AND RTCC and it's function?

2 Answers Sterling Wilson,

Explain the working principle of Vacuum circuit breaker and Air circuit breaker

10 Answers HP, Trinidad and Tobago Electricity Commission T TEC,

What is the criteria for deciding whther fire wall is required between two power transformers

1 Answers

Why increase in current leads to increase in conductor temperature?

0 Answers

For more Electrical Engineering Interview Questions Click Here