Transformer Wiring?

[Uglydog]

I'm puzzled again...
I'm reworking a Millrite with Z and X powerfeed. I've replaced the bevel gears in the knee, freed up the rust parts that are supposed to move and replaced the Z drive motor. The head and original Z drive motor were all 3 phase. Near as I can tell these 3phase was all that was fed into the machine. The main junction box fed directly into the old transformer box. Thus, 3phase to the transformer.

The DC X axis motor is getting a complete rewire by a DC motor guru.
The transformer and box appears to have suffered significant internal heat.
Thus, a new box and transformer.

However, how do I hook this up to 220v 3 phase? Where does the third incoming leg go? Looks like I jump H1 and H3 and connect to incoming Line1. And jump H2 and H4 and connect to Line 2. Where does the third Line 3phase leg go? I didn't have much to start with when I got this trauma victim.

I need 1110v 1phase out to the DC motor.

The first pick is a close up of the old transformer, the second pic is the new.



Thanks all for your ongoing patience!
Daryl
MN

 

[RJSakowski]

I'm not a 3 phase expert, but I don't think you can feed 3 phase into a single transformer. You would need to have one transformer for each leg. They may be housed in the same unit but there will be three cores, each with their own windings. The two you have shown would be single phase running on one leg of the 3 phase.

 

[Steve Shannon]

That's a single phase transformer. You hook one phase to it and take 120 vAC off the output for your controls, not your three phase motors. For them you just have the utility provide three phase at the needed voltage.


Steve Shannon, P.E.

 

[jim18655]

That's a single phase transformer so it only needs 2 of the 3 phase leads. Connect one of the 220 lines to H1 and H3 the other to H2 and H4. You get 120 from the X1 and X2.

 

[JimDawson]

That's a single phase transformer so it only needs 2 of the 3 phase leads. Connect one of the 220 lines to H1 and H3 the other to H2 and H4. You get 120 from the X1 and X2.

:+1:

 

[David VanNorman]

Do you have a Rotary 3 phase converter ? If you are running on just a spinner you might do well to take your 220 single phase of before the spinner. The spinner doesn't give true 3 phase . If you have true 3 phase it is no problem you can get your power from two legs of your 3 phase.

 

[Uglydog]

Great!!
Thank you All.
Cap off one leg.
Connect two of the 3 legs.

Is is silly for me to ask how a transformer makes a neutral out of two hots?

Daryl
MN

 

[Uglydog]

David VanNorman,
I'm not familiar with the term "spinner" please explain.
The guy I'm doing this for runs a 50hp RPC.
He is a weld fab guy, who runs large shears and benders.

Daryl
MN

 

[JimDawson]

Is is silly for me to ask how a transformer makes a neutral out of two hots?

You could ground X2 on the transformer, that would make it a neutral, which is described as ''a grounded current carrying conductor'' as opposed to a safety ground which is described as ''a grounded non-current carrying conductor''

 

[jim18655]

The transformer doesn't "create" the neutral it only transforms the voltage to 120v. You make the neutral when you bond one of the 120v legs to the frame of the machine. It doesn't matter which you bond to create the "grounded conductor" as long as you only connect one end the the winding. Get the elusive ohm meter out and check each 120v wire for continuity to the frame of the machine unless you can see the bond wire.