Transformer regulations

[rds1975]

Hello friends

I tried the exercise as mentioned in the question below. It is mispelled int he question as 23 ohms total resistance. Please correct it as 23 Ohms total reactance (I presume so).
I tried to get the voltage regulation of transformer using following formula based on engineering book.

Vr = Full load current (Total resistance * Cos Pi + Total reactance * Sin Pi) / Volatage in primary

Cos pi is 0.8
Sine Pi is 0.6

Total resistance = R1 +R2(V1/V2)
Total reactance = 23 ohms as given in the question.

Iam getting percentage regulation of 0.55 % as per the formula, but the textbook answere says as 3.06 %. I do not know how they derived this as steps are not given. Can anybody help me the steps.

Thanks and regards

 

[Russlk]

It seems to me that the lagging power factor is not effective because the V-A is given. Therefore full load amps = 30K/11K=2.73 amps and the input voltage reduction is 23 * 2.73 = 62.7 volts. The percent regulation is: (11000-62.7)/11000 = 99%

Anyone agree?

 

[Painandsuffering]

hmm

I must agree with russl I recently had to deal with transformers in my college class and aced the test after his help and after seeing his formulas and answers If my memory serves correct I think he is right.

 

[Painandsuffering]

Differences

the only differences I can find are in rounding 23*2.73=62.7 which it actually equals 62.79 which when rounded is 62.8 but I don't think this will have that large of an effect on the answers.