Trafo Tap Position

By elementary arithmetic.

Plz, show me the calculation procedure.

Since elementary arithmetic is beyond your skill set, even if I give you the correct formula I doubt you'll understand the answer.

My requirement is the concept of the calculation process.

Before making any comments plz think two times....

What? And spoil the education value of getting a poster to think independently?

This is CR4, not McDonalds! <other fast food outlets are available>

Before criticizing somebody trying to help you, you should think a little for yourself. I've yet to see anything that would tell me that you can understand any concept on calculation.

Ok, here's a question for you. Do you understand how I can quickly come to the conclusion that you have sixteen different tap positions?

Oh, I'm also surprised that this is an even number. Can you guess why I'm surprised?

My mistake, you should actually have 17 taps. I feel better now.

I am sorry for asking questions. I forget that site for such peoples those know every thing.

Since still no "Great " give me the answer then i try to solve it in this way

V(n)=(220x1.1)-[(n-1)x1.25x220/100]

Am I right?

I'll give you something more important than just giving you the answer, I'll give you the method to see if your equation is correct for yourself.

The key here is that you know the output tap voltage you should have at least three positions; maximum tap (242V), minimum tap (198V) and one less than maximum tap (239.25V). Your equation fits the standard form of a linear (straight line) equation of y=mx+b. So verifying that this line intercepts your known minimum and maximum points and one step produces the 1.25% increment means that you have found one of the valid formulas that solves your relationship.

amitabha0107,

You mentioned the tap changer range is -10% to +10% with the 17 steps of each 1.25%. This seems unusual to me. In general, the tap changer range is -5% to +5% with the step of 2.5% (5 positions only). Is yours one a real case?

You didn't mention which side the tap changer is located. Since, most cases the tap changer is located in high voltage side, it is assumed the tap changer is located in 220kV winding side.

Now come to your question. You have 17 tap changing positions. Let's mark them as 1 to 17. The middle position is 9^th which is the position for the rated voltage which is 220kV. The 1^st position is 220 x 1.1 = 242kV and the 17^th position is 198 kV. Finding the kV of all other positions is simple linear math.

Your equation seems correct. You can verify it with above method.

If the tap changer is located in low voltage side, replace 220 by 34.5 in your equation.

Hope this thing helps.

- MS