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StrayAlien
24th Mar 2018, 09:12 AM
Hi all,

A new-to-me Bridgeport followed me home yesterday. 2hp 3 phase.

The motor terminal box wiring looks like this:

372545

very neat. I figure this means it can be re-connected for delta so I can run it on a VFD? Maybe it already is delta (but as the machine just came from an industrial toolroom I doubt it).

I guess the next question is, if it can - any hints on how to reconnect the above?

All forum disclaimers apply.

Many thanks,

Greg.

StrayAlien
24th Mar 2018, 11:26 AM
After some kero and scrubbing, the rather obscured plate revealed itself.

372546

It looks like the 'lo volts' might be the connections for delta?

That what you are looking for Bob?

Greg.

BobL
24th Mar 2018, 12:24 PM
That is exactly what I was hoping for - am also hoping the wires themselves are numbered?

I assume you have a single phase input 220/240V VFD?
In that case you should wire it for the Low voltage.

The "MUST be a delta" is not necessarily the case, and only applies to to motors that are initially 3P ~415 "Y" connected and need to be run on 240V 3P.
When these motors are converted to ∆ this automatically makes them a 240V 3P capable motor.

For example take teh opposite, a 415V ∆ connected machine won't develop full power when connected to 240V 3P even though it is already a delta. Conversion to a Y will mean this motor will require about 800V 3P to develop full power.

BTW, if you were to wire the motor to high voltage is should (no guarantee mind you!) not let out any smoke and it should still run but it will only develop half power.

If you have not used that VFD before I suggest you wire it to another 3P motor and check that it works properly before trying the mill motor otherwise you will be dealing with a double blind situation.

BTW Am dead jealous of your deal! - the only consolation I have is that there is no way I could fit such a machine inside my shed. :(

StrayAlien
24th Mar 2018, 02:41 PM
Thanks Bob. Much appreciated.

Yes, I have a 2hp 240v VFD - and I have used on it some other motors - so she's good.

I'm neck deep in crud cleaning it at the moment so I'll check the wire numbering a bit later. When it comes to wiring it up to test it I may need some more advice on what wires from the 5 core to use.

Re the deal on the machine. Thanks. :-) I have been looking some quite some time but it had to make sense before I bid. For example, not long ago someone paid $6500 on greys for a series 1. Add on 15% buyers premium and they forked out about $8k for it. Holy moly.

Despite being quite a lump it doesn't actually take up too much more space than the Herless knee that it'll replace.

Thanks again.

Chas
24th Mar 2018, 08:56 PM
After some kero and scrubbing, the rather obscured plate revealed itself.

372546

It looks like the 'lo volts' might be the connections for delta?

That what you are looking for Bob?

Greg.


According to my understanding of the motor connection diagrams on the nameplate, the motor is star connected for either 440V or 220V. The windings to (7), (8), and (9) are internally connected together as star. The other set of individual windings (1) - (4), (2) - (5), and (3) - (6) are either jumpered in series with the star set to provide a 440V star connection, or they are jumpered for star (4)-(5)-(6) and connected in parallel with the star set of windings for 220V.

Hope this helps, Chas.

BobL
24th Mar 2018, 11:16 PM
When it comes to wiring it up to test it I may need some more advice on what wires from the 5 core to use.

You'll need more specific advice from someone who knows about mills and Bridgeports.
My understanding is that Bridgeports have other motors on them like the table motion motors and a coolant pump motor
My question is, are these 3 or single phase motors?

If they are single phase it will be far easier to strip out all the 3P wiring and switches off the machine and rewire it all using single phase line.
If they are 3P things will get complicated if you use the same wring and my preference would be to instal a separate single phase line and safety switch to control the VFD/motor and runs all the the stuff from 3Phase. You can't use a single VFD to run all these motors

StrayAlien
25th Mar 2018, 09:15 AM
Chas, thanks. No delta in there? Is that what you mean?

Bob, thanks also. 'Luckily', this garden variety BP has no shmancy extras. Just the motor - no power feed or coolant motor. :)

EDIT: the DRO has its own 240 SP plug, but a curious red wire is wound around the top of a screw on the mill power box and then attaches to two points on the DRO unit.

BobL
25th Mar 2018, 09:31 AM
Chas, thanks. No delta in there? Is that what you mean?
Bob, thanks also. 'Luckily', this garden variety BP has no shmancy extras. Just the motor - no power feed or coolant motor. :)
Good in that case strip off all the old wiring and switches and start again.


EDIT: the DRO has its own 240 SP plug, but a curious red wire is wound around the top of a screw on the mill power box and then attaches to two points on the DRO unit.
How about some pics?

Chas
25th Mar 2018, 05:01 PM
[QUOTE=StrayAlien;1933465]Chas, thanks. No delta in there? Is that what you mean?

Yes, no delta option; the motor is wired either 440V star (HI Voltage) or 220V star (Lo Voltage). I would think your VFD will work into 220V star, but I cannot speak from experience.

Chas.

StrayAlien
25th Mar 2018, 06:23 PM
Bob, pics. The red wire connected to nothing in the power box so I'm guessing it might be an earth using some convenient red wire .. ?

372593372594

And re throwing it all out:

372595

Not a chance! :) :)

Chas. Thanks. disclaimer: I am quite an idiot with electrics. My small brain had equated 'star = bad, delta = good' for running a VFD on 240. But, your message is sinking in ... 240 star should be just a good. Basically, who cares .. it is 3P running on 240.

I checked the wiring. It is numbered. Twice! Each wire not only has the number word on it like (say) 'seven', but also a string of 7's down the edge of the wire as well. Nice.

I'll give it the VFD smoke test in the next day or two.

Greg.

StrayAlien
25th Mar 2018, 08:41 PM
Actually, I gave it a test just now. Rewired stuff according to the plate and it runs just fine on the 2hp VFD. The forward/reverse switch also works.

Nice. Thanks Bob . Thanks Chas.

Greg.

BobL
25th Mar 2018, 08:58 PM
Good work.

Red wire on DRO - exposure like that does look lake an earth - pretty foolish using a red wire though.

Second picture of the red wire at the back of the DRO.

Can you follow that red wire that heads off out of the picture.

What make/model is your VFD and is it a Vector drive?

Chas
26th Mar 2018, 08:20 AM
Up to the 1960's, red was the designated colour for AC earth wiring in Germany. Perhaps the wire on that VFD had its origins in that country, or someone from there?

Chas.