Solving Question (1)

shermaine said:

I have got some questions posted on this website.
Any one can help me solve it? Pls advise. Thanks.

Q(1) A single-phase, 100kVA, 11000/2200-V, 50Hz transformer has the following parameters:

R at HV = 6.0 ohm
L at HV = 0.08H
Lm at HV = 160H
R at LV = 0.28 ohm
L at LV = 0.0032H
Rc at HV = 125Kohm

(a) Obtain the approximate equivalent circuit of the transformer referred to the low voltage side.

(b) Use this approximate equivalent circuit to determine the efficiency of the transformer when the transformer delivers full load at rated voltage and 0.85 power factor lagging.

(c) When the high-voltage winding of the transformer is connected to a 1100v supply through a cable whose impedance is 1+j3 ohm and a load Z L=50 + j15 ohm is connected to the low-volatge winding, determine the load voltage

(d) At rated voltage, determine the loading of the transformer at which the efficiency is a maximum and calculate this efficiency if the load power factor is 0.6 lagging. Discuss how the power factor will affect the maximum efficiency.

Pls advise.
Thanks.

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Russlk said:

I could have figured it out 40 years ago, but I am too lazy to do it now.

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That's no homework.
It's some question i got ....I have tried and i want to confirm the question.

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