Xfmr & vd

[ptonsparky]

25 KVA transformer 480 to 240/120 secondary. How much does the impedance of the transformer play into the voltage drop at the end of the secondary? Where do I fit that into my VD calculations?

I have a 210 foot run with twice the VD expected. #4 cu @ 35 amps results in about 110v. Line to neutral. 121v no load.

To late for this one but don't want to repeat it.

 

[dicklaxt]

I think they are stand alone VD problems,,,,,the primary VD is based on 25KVA and the secondary is based on the load.

dick

 

[ptonsparky]

15 KVA not 25. Worst case I have .5 volt drop on primary side of transformer. Sure doesn't account for the secondary drop.

 

[don_resqcapt19]

There is a discussion of this issue here.

 

[bob]

I have a 210 foot run with twice the VD expected. #4 cu @ 35 amps results in about 110v. Line to neutral. 121v no load.

My calculations give 4.5 volts drop. did you check the primary voltage with load along with the secondary at the transformer?

 

[dicklaxt]

I'm confused,why would you want to figure the secondary VD at 210 feet to the load by using the impedance of the transformer?

dick

 

[ptonsparky]

I'm confused,why would you want to figure the secondary VD at 210 feet to the load by using the impedance of the transformer?

dick

Don't know if I should or shouldn't. I need to check the link above.
Just trying to figure why the vd is excessive. I will check link, get ducks in row test again. Not sure which taps help used on the transformer either.