Transformer humming loudly

[hillbilly1]

Got a call from one of my guys saying he replaced a transformer that humming loudly, the new one was just as loud. After he sent me the pictures, I wonder how it worked at all! LOL! (Left pic is H's, right is X's, 480 volt step down to 120/240 single phase)

 

[LarryFine]

It's hard to tell what you're showing us.

 

[hillbilly1]

It's hard to tell what you're showing us.

Just edited so you would know. Note phase colors on wires.

 

[LarryFine]

I see the brown and orange, no yellow, and I see the green and white wires and the jumpers.

Where does the black wire jumped to the green come from, or go to, whichever is applicable?

 

[hillbilly1]

The two greens are on H2 and H3 (where the jumper is) The black is on X1 where its supposed to be, the Red is on X4, white on X2 and X3, where they are supposed to be. The issues are the greens! This is stepping down, not up! Don't know who originally wired it, but he copied what they did.

 

[LarryFine]

Okay, so it's a 1ph transformer. Knowing that helps. I guessed at step-down. Lemme look again.

Okay, now I know what I'm looking at. Looks like a 240/480 transformer wired for 480 to 120/240v.

There should be nothing on the primary jumper, and the greens should be moved the secondary jumper.

 

[tank728]

Transformers hum because they don't know the words.

I couldn't help it

 

[ptonsparky]

The two greens are on H2 and H3 (where the jumper is) The black is on X1 where its supposed to be, the Red is on X4, white on X2 and X3, where they are supposed to be. The issues are the greens! This is stepping down, not up! Don't know who originally wired it, but he copied what they did.

That is a dilemma and a waste of time.

I would like to think my guys would have questioned the original install as soon as they opened it, but I couldn't guarantee it. I've never seen it before either. Regardless, they will know as of Monday. Thanks for the pictures.

I assume the correction helped.

 

[hillbilly1]

That is a dilemma and a waste of time.

I would like to think my guys would have questioned the original install as soon as they opened it, but I couldn't guarantee it. I've never seen it before either. Regardless, they will know as of Monday. Thanks for the pictures.

I assume the correction helped.

Transformers seem to confuse a lot of electricians for some reason. They are really simple once you know how they work. He called back and said it was so quiet he thought it wasn’t working! LOL!

 

[kwired]

Okay, so it's a 1ph transformer. Knowing that helps. I guessed at step-down. Lemme look again.

Okay, now I know what I'm looking at. Looks like a 240/480 transformer wired for 480 to 120/240v.

There should be nothing on the primary jumper, and the greens should be moved the secondary jumper.

If the supply is a 480/277 source, that grounded jumper to the primary center tap means each half of primary is seeing 277 instead of 240, extra excitation of the primary coil and will make more noise.

If primary were from a 240/480 source, there would still be some stray current issues, but may not cause any noticeable problems