Problem- Transformer wiring

[pjensen]

Hello all,

I have a 1985 VMC40 that uses an input transformer that doesn't look like any transformer in the currently available Fadal manuals.

It is currently configured to take single phase 120V input, and make 120V single phase output for the rest of the system. (Except the spindle motor inverter, which gets a direct feed from the 3phase input, and bypasses this transformer completely.)

Unfortunately, I have 3 phase, and need to feed it ~208V which is what you get between two legs of a 240V 3 phase system.

This transformer has 9 input wires on the high potential side, and 6 output wires on the output side, so I think it is probably configurable to handle different situations, based on which windings are connected.

Does anyone have any information on this transformer, and how it's internally wired? The only markings on it are the number "337" and each wire has a number, from 1 to 15.

Any help would be appreciated!

Thanks,

-Peter

[Al_The_Man]

If it is a single phase transformer you could temporarily disconnect the secondary, and by ohm meter test for the most resistance between the primary winding and start by feeding in the 208 in there and see what the secondary comes out to, reduce to lower tap until the correct secondary voltage is seen.
I know it is not the best scenario, but in the absence of any other info, it may come down to this?
Al.

[carbidecraters]

You dont have a A2-A6 B2-B6 C2-C6? Sounds like it would be a old model.

[pjensen]

Yes, it's a 1985, so it's pretty old. There is no A/B/C lines on the input transformer, like all the Fadal manuals say there should be.

By breaking a few electrical codes (just as a quick test), I used the ground wire to get a true 120V input to the machine without changing the transformer wires. Now all the lines labeled 120V are, in fact, getting 120V, not 103V like before.

Unfortunately, my problem hasn't been solved. The machine will still get power glitches from time to time. It happens most often at the beginning of a tool change, but it can happen at any time, even when the machine is completely idle.

What happens is the power goes out for a fraction of a second - all the lights, display, everything flick off. I can hear some large relays inside the machine also clicking off and on. The problem is, although I know certain main power relays are turning off, I don't know if that is a symptom or a cause.

I had thought the low voltage on the 120V line was causing the problem, but apparently not.

I'm going to go get my multimeter and start monitoring voltage levels over time and try to see if I can find what's causing the problem...

Does anyone have any suggestions as to likely culprits? Seen something like this happen before, and know what did it?

Thanks for any help!

Best Regards,

-Peter

[Al_The_Man]

It sounds very much like a large load is happening and saturating the Transformer momentarily?
You may have to try and monitor exactly what picks up at the time.
Al.

[pjensen]

I pulled out all the relays on the 1180-0 power-up sequencer, and the problem (so far) appears to have been resolved. Looks like there was a bad connection, and the power sequencer certainly has the ability to interrupt power to the machine.



Thanks for all the help and suggestions!

Best Regards,

-Peter

[carbidecraters]

813 single phase

[pjensen]

Thanks for the pic -- that sure isn't anything like the transformer in my machine. I think this 1985 model is just too old

My project over the next year is to update the control and electronics.

Cheers,

-Peter

[pjensen]

Just to be clear, when I said I pulled out all the relays on the power-up sequencer, I then promptly PUT THEM BACK. All I did was re-seat them.

I don't want somebody finding this thread sometime with the same problem and thinking I just pulled out the relays and tossed them in the trash ;-)

I now have a copy of the 1985 Fadal VMC40 Maintenance manuals, which has wiring information for my "Glentek T337" transformer. If anybody needs a copy, PM me.

Cheers,

-Peter