Power feed Wiring for Bridgeport Mill

============= In the US it is common that these mills are wired to run off 220 volts 3 phase. Any one of the hot 3 phases should produce 110 volt single phase to neutral. If you are running 220v 3 phase 50 cycles, you only alternative may be to get a transformer, although I would check to see if you have a dual voltage motor on the Align power feed.

The Align website at

show only 110 volt operation but 50/60 cycles.

A quick google search show that in 220V countries the power feed is sold with a stepdown transformer. For example

your might try emailing snipped-for-privacy@att.net to see if they have a

220v motor.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Chris,

I have an older step pulley Bridgeport that I fitted an Align to, it didn't have power feed fitted before that and had no 110V provision. I added an external stepdown transformer and routed the power to it and

110V back into the control box. The 110V was then fed to the Align via a new contactor which was powered off the circuit which energises the main motor, in that way when the motor was off so was the powerfeed, standard practice I think and it was shown in the Bridgeport manual showing the wiring diagram when fitted with a powerfeed.

This would only be true if the 3 phase is Wye connected. A delta connection has no "neutral" and wouldn't do this.

Right? Pete Stanaitis

---------------------

I meant 440 3 phase 50 cycle. If the "normal" single phase voltage in the UK is 220 then the "normal" threee phase will be

440.

Sorry about the brain fart.

As far as delta v wye connection, its not the motor, its the supply and these are almost always 5 wires in, 3 phased hot, 1 neutral and one ground. You might run into a "wild leg" condition where the voltage of a hot wire to neutral is not 110 (or 220) but is correct between the three phased power wires.

While using only one leg of a three phase circuit will cause screams about "power factor" from the electricians, it is almost impossible to even measure for a limited use fractional hp motor on a power feed. A possible exception is if you are downstream from a RPC or VFD [rotary phase converter / variable frequency drive]

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

The one in our shop is on an extension cord from a nearby wall socket.

Got a transformer? 220v to 110v AC?

Gonna need one.

Don't get your hopes up on finding anything integral to the Bridgeport. You are putting an aftermarket item on it, thus, an item that the makers did not plan around, or spend profitless money providing for.

Cheers Trevor Jones

George, Strictly speaking if you refer to the 3 phase power that has available 120 nominal from phase to neutral then the phase to phase voltage should be refered to as 208. This is Y connected. There is the Delta connected that does indeed produce 220 or 240 but then the neutral is the centertap of one leg and the voltage from the other (wild leg) will be a lot higher than

120 Maybe I shouldn't get involved in this. ...lew...

Well, sometimes. Center tapped delta is very common in some parts of the US. This is the service with the 'wild', 'high', or 'bastard' leg that gives nominal 208 volts to neutral, while the other two give the expected 120 volts. Usually the mill will be supplied by only the 3 phases and no neutral so there is no 120 or 208 there (not counting doing something dumb like using ground as neutral). Sometimes there might be a 120 vac circuit adjacent to the 3 phase disconnect for cord and plug connection. I just use a separate SO cord over to the nearest

120 volt outlet for power feeds, coolant pumps, DRO's, work lights, etc.

Paul

=========== Note UK extension on OP's email. Chris

IIRC normal wall outlet voltage in the UK is 220v 50 cycle single phase.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Careful, George. If the 3 phase is delta, the high (wild) leg to ground is something like 208 volts----hardly the same as 120 volts.

Typically, if the voltage in question is 208 volts, phase to phase, it is star and what you suggested is true. If the voltage is 240 phase to phase, it's delta.

The wild leg is normally flagged a fluorescent red, and is found on the B phase of a panel. Bruce may even correct what I've said, but I've had delta service for all my shops and know all too well that you have to be careful about picking 120 v from the panel.

In this case, if the wiring is 5 wires, all that is required is to use either the A or C phase, along with the neutral, and you have 120 volts. If it's only four wires, one ground, code no longer allows for the ground to serve as a neutral.

Harold

Well spotted George, the guy did have at the bottom of his post that he was in Kent UK also. The voltage used to be nominally 240V but due to harmonisation with Europe is now nominally 230V. It is the phase to neutral voltage so one phase of the 3 phase system and the neutral. 13A as standard in the UK as well so 3kW from the wall socket.

That is not neccessarily true. 208 V Wye circuits will provide 120 V line to neutral. A 220 V Delta circuit may not have any associated neutral. If it did, the L-N voltage would be a NOMINAL 127 V, which sounds marginally OK, but I don't know of any 220 V power. It is usually a NOMINAL 240 V, and actually runs higher. At 240 L-L, you'd get 138 V L-N, which won't be good for it.

Does the OP not have an ordinary 120 V outlet within reach? What about for lights, coolant, etc?

Jon

Yes, you absolutely MUST know what power you actually have before trying to do this, and then measure, anyway. There are both CORNER-grounded and CENTER-grounded open-delta systems still in use, especially in smaller shops, ma and pa groceries, etc. The corner-grounded systems are real obvious as there are only two breakers on a supposedly 3-phase system.

Corner-grounded delta just uses two single-phase transformers. The center-grounded scheme needs one transformer center-tapped like a home

120-240 transformer. It can be set up with just one other transformer as open-delta, or with 3 transformers, total.

Jon

OP in Kent UK so 230V mains outlets, no 120V without transformer.

Thanks all - I have now ordered a transformer.

Rgds

Chris

208 V Wye circuits will provide 120 V

Yes, of course, I should have noticed. And, no 208 V there, as no need to create these rather bastardized 120/208 V systems to run 120 V office equipment and 3-phase gear like central air conditioners off a single transformer.

Jon