Transformer Re-wiring Assistance Needed 440 to 220

[dalmatiangirl61]

I rewired a machine to 220v 3ph and its not working, I have tracked the problem to this transformer, and not sure if it can be re-wired to 220v. Initially I thought its only purpose was to provide 110v for a worklight, but it also provides power to the Sprecher Schuh contactor coil, which sends power to the main switches. With power on I can manually move it and it will hold, power reading between the 0 and 110 terminals on transformer is only 77v. Can this transformer be re-wired to output 110v by rearranging taps 1 thru 4? Voltage readings on those taps are in the last pic.
Thank you.

 

[SAF]

Was the OEM voltage setup for 440V? How do you have it wired now with your 240V feed, to get the voltages you show?

The primary has two 220V coils. At 440V they should have been wired in series. For 220V they should be wired in parallel. If you have 240V feeding a 220V primary coil, your output voltage will be on the high side as well.

 

[dalmatiangirl61]

Was the OEM voltage setup for 440V? How do you have it wired now with your 240V feed, to get the voltages you show?

The primary has two 220V coils. At 440V they should have been wired in series. For 220V they should be wired in parallel. If you have 240V feeding a 220V primary coil, your output voltage will be on the high side as well.

I have a manual for it here somewhere, need to find it....iirc it states the machine can be run on 220 or 440v, but I don't always rc right any more. I changed motor connections to 220v, nothing else. A thought crossed my mind, disconnect all inputs to transformer, cap off 2&4, jump 3&1 to the 0 & 110 terminals, seems like kind of a hack and not right though. Not quite following you on how to wire in parallel, a quick sketch would help.

 

[SAF]

If it's still wired for 440V, then show how it's connected, for the readings you obtained.

 

[dalmatiangirl61]

If it's still wired for 440V, then show how it's connected, for the readings you obtained.

I have not changed any of the wires on the transformer, so yes it is still wired for 440v input (0-220 & 0-220), and since its only being fed 220v (0-140 & 0-140), it is only outputting 77v. Can it be re-wired to input 220v and output 110v, if so, how? Or would it need to be replaced?

 

[SAF]

You need to show how its connected currently, we could guess at how to connect it, but you may not get favorable results with guesses. Show the input connections, it's a euro design and may be different than a US design.

 

[dalmatiangirl61]

Terminals 1 and 4 are hot, terminals 2 and 3 are neutral as currently wired.

 

[SAF]

I don't believe that your #2&3 terminals are connected to neutral, typically there is no neutral conductor supplied to power 3 phase equipment. Instead there should be a jumper installed between 2&3 for the high voltage connection.

This drawing shows both primary connections for your typical dual voltage control transformer.

 

[dalmatiangirl61]

Forgive me, I struggle to find the difference between neutral and ground. My current power into the building is single phase, 2 hot wires and a neutral/ground, at the 3ph rotary converter panel its still just a neutral/ground. I think, maybe wrong, that this is the only machine that utilizes a neutral leg.

I will study the schematics you provided in the AM.
Thank you.

Edit: This machine was made in Italy, not sure how/if that affects the wiring. I did find it odd that wiring motor for 220v is a double delta connection.

Edit again: There are 4 wires into this machine, 2 hot manufactured legs, 1 hot artificial leg, and the neutral/ground leg.

 

[EmanuelGoldstein]

From memory, the US dual-voltage xformers I've rewired were like SAF's drawing, 1 and 4 hot, 1&3 plus 2&4 jumped for low, 2&3 jumped for high.

You can check by running an ohmmeter across 2 & 3. Or it's possible the eyetalians label things different, but from that info you should be able to figure it out.

Keep your hand near the power switch when trying it

 

[SomeoneSomewhere]

Yup, jumper 1-3 and 2-4, remove 2-3 jumper.

The 2-3 jumper should not be connected to either neutral or ground or things would probably go bang.

 

[dalmatiangirl61]

I see said the blind man to the deaf dog! That is a jumper between terminals 2 and 3, not neutral wires, just had to bend over and peer up there with a flashlight to see it, that is what I get for letting my eyes do the thinking. The way the label on transformer reads 0 made me think it was neutral the same as the 0 next to the 110 terminal is neutral.

 

[dalmatiangirl61]

Ok, got it sorted out, seems the italians don't quite follow the same wiring, jumpers between 2&4 and 1&3 is not correct, it gave zero voltage (and no smoke!). Removed those jumpers, used ohm meter to verify ends of the coils, and put jumpers between 1&2 and 3&4, with this I was getting 140v output. A little testing determined one of the input wires to transformer was the artificial leg, after swapping a few wires around it is now outputting 120v.

Machine is still not quite right, I think one of the main switches is bad, and its stuck in ON position, but getting machine to run requires manually engaging the S-S contactor, once engaged it will hold itself in. Other problem is probably related to rpc output voltage, I'll revive that thread.

Thank you to all with advice.