Line Voltage too High

[FredC]

have enough big universal transformers on my mezzanine to power every machine at the voltage it likes if I ever pony up for the big 480 service I want.

Hmm. My 3 -phase ranch electrics for the irrigation run almost 500V instead of 480V. Hope you do not jump out of the frying pan into the fire. You might want to check with neighbors before you jump.

 

[Garwood]

Hmm. My 3 -phase ranch electrics for the irrigation run almost 500V instead of 480V. Hope you do not jump out of the frying pan into the fire. You might want to check with neighbors before you jump.

I don't know why that would matter? 480V to 500V is a 4% difference.

If I'm using a 480 to 208 transformer to get around 240 then 500 line voltage is prefect.

All the transformers I have use multiple taps labeled 190, 200 and 210 for the desired output and for each leg. So if I had 500 coming in, tapped it for 480 and 210 out I'd likely end up right in the 230V range where I want to be.

I have several 480 only machines. They are currently run from 480-240 stepdown transformers flipped backwards. When my voltage is 245. they are 490 and don't seem to care in the least.

 

[FredC]

Garwood,
You mentioned 250+ in times past, I think I would ask the power company or neighbors to make sure you do not get 510+ and have problems. I had a few problems with center pivot controls at 498. The blown parts were only one time each, so no telling if they were going to blow any way or if the 498 contributed. Asking a couple questions before committing does not cost much.

 

[rons]

Several of my motors don't like this and vibrate loudly on startup till they start turning,
just like they were saturating. I have corrected the situation by using a 230-208 stepdown transformer, which
when powered by 250V gives 230V out, which my machines are happy with .

On startup there is vibration, then the motor runs.
It appears that the increase in line volts has offset your start capacitor arrangement.
Your transformer is one way to fix this. A few capacitors are less costly.