Transformer Rewire

[Jody Boehs]

Hello,

I am in the process of wiring a press brake that runs on 575V wired in Wye configuration. The shops power is 480V and it is also wired in Wye configuration. Therefore, a step-up transformer is needed. A previous electrician ordered one with primary voltage of 480V and secondary of 575V. But, it is a Delta-Wye transformer. Can this transformer be rewired on the primary side to work in this scenario?

I was thinking I could disconnect one lead on each winding and tie them together to create a Wye primary. Am I thinking right?

Also, it looks as though in a step-up transformer the connections are opposite. The H connections are secondary. And the X connections are primary. The reason I say this is because the nameplate on this particular transformer shows the X terminations are wired in Delta and the H terminations are wired in Wye. See nameplate below...

 

[augie47]

The transformer will work as is. Just connect the primary to the phases and don't worry about the primary neutral.

 

[mbrooke]

If you somehow managed to rewire the primary from delta to wye, you would need an 830 volt phase-phase supply. It is fine as is. Near 100% of dry type transformers in buildings stepping voltage up or down is delta on the primary.

 

[Jody Boehs]

If you somehow managed to rewire the primary from delta to wye, you would need an 830 volt phase-phase supply. It is fine as is. Near 100% of dry type transformers in buildings stepping voltage up or down is delta on the primary.

Ok thank you for the info! I have not yet rewired it. But why would I need that much voltage for the primary if I rewired it to Wye?

On this particular transformer though, the primary wire will go to X1 X2 X3? And Secondary will go to H1 H2 H3? Or why are those reversed on the label? Is it because it’s a step up transformer? (This is the first Step-up transformer I have worked with so I’m kinda new to this realm.)

 

[mbrooke]

Ok thank you for the info! I have not yet rewired it. But why would I need that much voltage for the primary if I rewired it to Wye?

The primary coils as they are now are 480 volts. By going wye, those same 480 volt coils are no longer phase to phase connected but phase to a neutral point- meaning in very over simplified terms your 480 volts has to go through two or three coils instead of just one.

On this particular transformer though, the primary wire will go to X1 X2 X3? And Secondary will go to H1 H2 H3? Or why are those reversed on the label? Is it because it’s a step up transformer? (This is the first Step-up transformer I have worked with so I’m kinda new to this realm.)

Technically they should be H1, H2, H3 for the primary and X1 X2 and X3 for the secondary even if stepping up, it incorrect as pictured, but I guess the manufacturer for what ever reason thought it would work the other way around label wise. Double check the output voltages before applying power to the machine its connected to.

 

[LarryFine]

I was thinking I could disconnect one lead on each winding and tie them together to create a Wye primary. Am I thinking right?

Negatory. You should connect the delta primary to the supply just as it is, with no neutral connection.

When using a wye primary, the transformer's neutral should be left floating and powered as if it was a delta anyway.

 

[LarryFine]

Technically they should be H1, H2, H3 for the primary and X1 X2 and X3 for the secondary even if stepping up, it incorrect as pictured, but I guess the manufacturer for what ever reason thought it would work the other way around label wise.

I believe the H designation means the higher voltage, whether stepping up or down.