3phase Motor wiring 480/208v

[ojh]

Hi all, I have a machine that I believe was connected to 480v, I need to connect it to 208v. It is a German built machine with Seimens motors and I have no information on it. I have taken one motor apart and find the wire terminology different from what I'd expect, I expect to see T1, T2 etcetc but what I find is: 9 wires
Ub; Vb & Wb joined to Ua; Va & Wa
with Xa; Ya & Za all connected together by a strap.
L1; L2 & L3 connected to the terminals for the Ua, Ub; Va, Vb & Wa, Wb connections.
I am wondering if, in fact, this machine is already connected for 208v
Thanks for your assistance, what little information I have is written in German and I'd really like to get the machine up and running, it's a Trumpf CN-701
OJ

 

[telectrix]

looks like it's wired in star. this configuration is for 415V. usually the lower voltage is 230V 3 phaseand you would connect the windings in delta. it should run as it is but not as fast.

 

[telectrix]

look at the 6 lead diagram. showing both standards of identifying both T system and uvw.
http://catalog.wegelectric.com/img/Wiring_Diagrams.pdf

 

[ojh]

The 'star' is what we'd call 'Y'?
I'd better ring out the windings and then I'd know each end, I'd expect it is the 'a' and 'b'.
It is the strap joining the three windings (X, Y & Z) that throws me, would that be the center of a Y connection that I normally wouldn't see? and I should regard this as a 6 wire motor?
Thanks for the responses, I'm out of my depth here and this is a great help.
OJ

 

[telectrix]

a photo would help, but as you describe it, that strap appears to be the star point connection. did you say 9 leads? if so, it's one of the first 2 diagrams. the windings are u1 u2: v1 v2: w1 w2. check with an ohm meter.

 

[ojh]

I rang them out, Ua to Xa, 1.9ohm; Va to Ya, 1.9ohm; Wa to Za, 1.9ohm
Vb, Wb & Ub all read 3.0ohm they all read together.
I measured everything totally disconnected, none of it was read thru a terminal block or anything. I read wire end to wire end.

These might be pictures or just internet gobbledygook

 

[Lucien Nunes]

There's a risk of confusion here as this is a UK forum and the OP is in the USA looking at an older European motor. The service voltages are different and multi-voltage motors wound differently and marked differently in the three locations. UK readers note that US-market motors 'high' and 'low' voltage are not equivalent to our 230V and 400V and that you can connect for star-delta starting in either high or low voltage config, that is why there are so many leads.

Take a look at the bottom of page 2-41 here: http://www.moteursbsc.com/media/other/133841-Connexions.pdf This is the old German coding which is what I think you have. In a 9-wire motor, either the elbows or one star connection is hidden inside (seems to be your X). Does this make sense? It would be interesting to see a close-up of the data plate - it's not a dual speed pole-changing motor is it?

 

[ojh]

I think you've nailed it! As soon as I get my head clear I'll sit down with the schematic and see if it matches up, it sure likes right.
The name plate is bright chrome plated, all but impossible to read and very small print, I halfway know what should be written and what to expect but a normal person wouldn't have a clue. Couldn't get a picture.
Some info from the name plate:
230/460v Y/Y 8.7/4.35a
Baugr. 100L (Frame?)
Bauf. 83 (Power Factor?)
60hz
1715rpm
Thanks, OJ

 

[Lucien Nunes]

Aha. So it's single-speed, always Y (star), high voltage twice the low. In low voltage there are two separate Y- config windings working in parallel. One (made of the three 'a' sections) is fed from the line at Ua, Va, Wa, the other ends of these are star-connected by the strap Xa, Ya, Za. The other set ('b' sections) is supplied from the line at Ub, Vb, Wb and the other ends of its windings (would be Xb, Yb, Zb) are internally star-connected and not visible in the terminal box.

So it sounds like it was already connected for 230V. When changing any wiring in a 9- or 12-lead motor, ensure not only to get the phase sequence correct between the two sections of windings but also the phasing of the a's versus the b's. Otherwise it behaves like a short-circuited transformer and gets fried pretty quickly!