How to use 3 phase 11 KV PT to measure 1 phase 11 KV? 3

[edison123]

How to use a three phase 11 KV PT to measure a single phase 11 KV to ground voltage?

Should I connect the single phase 11 KV terminal to A of the three phase PT and the single phase ground terminal to B of the three phase PT?


Muthu

http://www.edison.co.in

 

[7anoter4]

In my opinion the voltage between A and B [low voltage terminals] has to be 0.11 kV and the voltage between A and N has to be 110/sqrt (3).

 

[RRaghunath]

Star points on HV and LV windings of the PT are accessible, isn't it! Can we not connect the single phase voltage between A & N on HV side and take output from a & n on secondary side!
What you suggested (A-B & a-b) also should work and probably better as the PT will work at much lower flux density as 11kV/srt3 is being applied to the PT terminals meant for 11kV.
I don't see there will be any problem as long as we insulate the remaining terminal on HV as well as LV and also the neutral terminals, adequately.

 

[edison123]

Thank you both.

Yes, the secondary star point on the left is accessible while the primary star point seems to be encapsulated.

I will try with input between A & B first, measure across both a&b and a&n.

Muthu

http://www.edison.co.in

 

[waross]

Input to A-B, output from a-b.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[scottf]

The nameplate says a Wye primary and Wye secondary.

So, to use as a 1-phase VT, connect from A-N on primary and a-n on secondary.

RRaghunath - given that it is marked as wye / wye, and looking at the physical nature of the design, I would not recommend connecting A-B : a-b. Also, from an accuracy perspective, by the letter of the standard operating at 57.8% of rated voltage would not be acceptable, if using for metering. I can't read the hand-written nameplate well...I think it says acc class 1, but not sure.

 

[waross]

Yes, the secondary star point on the left is accessible while the primary star point seems to be encapsulated.

If you can locate a primary star point then use Scottf's advice.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[scottf]

Waross-

I would be willing to bet that the neutral end of the primary windingis is what is under the black rubber-like cover coming out of the unit in front of the high side stem.

Frankly, that unit looks like it was made in someone's garage and I would just buy a new 11kV indoor single-phase VT and be done with it.

 

[waross]

I have to agree with you on all counts, Scott.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[edison123]

Update.

Applied 11 KV to 1 KV between A & B and measured 110 V to 10 V at a & b.

Applied 11 KV to 1 KV between A & N and measured 110 V to 10 V at a & n.

This is for testing purpose, not for metering.

Thanks again for your valued inputs.

Muthu

http://www.edison.co.in