Voltage Difference Calculations

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Don't forget the cooling fans.

I don't see how any of these numbers match up.

Hardly seems possible. The transformer ratio suggests something on the order of 600 volts at the primary.

...either that or a serious undervoltage issue with the incoming power, perhaps.

One wonders why the protection equipment didn't operate.

It was being cooled by the fans.

Perhaps you talking about PT secondary voltage possibly provided on 14.4 kv side. Or it could be that you are applying low voltage on 69 kv side to check transformer performance. You need to offer more data than provided.

What If I consider there is another distribution transformer at the secondary of the regulator with ratio 14400/120 V.How can I solve the problem then?

Please post the revised sketch.

This is starting to sound like homework, which we do not do.

Determination of Transformer Rating

Now we are perhaps moving in the right direction. I am assuming the distribution transformer is not having voltage regulation taps. Now details of regulator, whether stepless type or stepped type is required. If stepless type is provided, the primary voltage cannot be calculated, as irrespective of incoming voltage, the output voltage will be maintained constant. If stepped type, the tapping at which the regulator is stationed at the time of measurement is required along with no. of taps and each tap percentage regulation. Next is the 69 / 14.4 KV transformer. Does it have any stepped voltage regulation facility. If yes, details as above is required. If all these details are available, then we can back calculate the primary voltage at the instant at which you have measured the distribution transformer output voltage.

You can't, unless you provide the load current and impedances. No load, open circuit voltage is easy though, if you assume ideal transformers.

With the limited infor given, it looks like 560.68V.

Homework for sure! then Guess if correct and risk it (!?)

This problem in itself is confusing so Let us analyze it:

(i) Load side voltage = 121.4V

(ii) Regulator tap ratio is 1.0375 and this approximates to 1.04. Clarify!

(iii) Transformer ratio is 69kV/14.4kV. It seems to be the voltage ratio, is it?

(iv) Transformer tap is 67000/65200. It seems to be the turns ratio, is it?

Now the ratio of the primary voltage(Vp) to secondary voltage (Vs) is DIRECTLY propoartional to the turns ratio,i.e Vp/Vs = Tp/Ts.

The above does not meet that equivalency. More and clearer information are needed for anyone to give some reasonable solution.

Triniboy,

67000/65200 seems to be the range that the regulator will be able to handle for fine tracking of the voltage ( 67000/65200 = 1.0276). It cannot be the turn rations of the transformer since that will have to be 69/14.4.

I am sure you can do the rest.