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Bradford Metalmaster 440v to 220v

FJsapper

Cast Iron
Joined
Nov 18, 2020
Location
Sterling Heights, MI
I am continuing to work through the Bradford Metalmaster posted in the vintage section (https://www.practicalmachinist.com/...rd-metalmaster-384378/index2.html#post3671277).

I am starting to work on how i am going to power this thing. The power hookup in my garage is for 220v single phase. I would like to run the lathe on 220v 3ph so a VFD will be involved. This will be my only piece of equipment running on 220v so i dont see the need to use a RPC. I also dont think i need any more HP rating for the work i plan to do so 440v and a step up seems like a waste. I see two options:

1) Re-wire the motor for 220v 3ph (if possible) + VFD

2) Acquire a new 220v 3ph + VFD

Only 3x wires protrude from the casing. It seems as if it was re-wired once before and converted to 440v. The data plate was re-stamped at some point and there was a service tag on the motor body. Does this mean it cannot be re-wired unless i start picking the windings apart to find all the different leads? Is there a way to confirm what the motor is actually wired for since i have some conflicting information?

If I elect to get a new motor at 220v 3ph will there be any significant re-wiring or swap of components of the lathe electrical system to accommodate (besides VFD)? Or will I be able to wire it up the same was the 440v was wired?

Data Plate reads 3hp, 1200rpm, 440v stamped and original voltage marked out

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This was how the motor was hooked up to the machine :angry:

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Opened the non-shaft end of the case

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Three leads disappear into the windings

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The motor hookup fed into this internal junction box

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Wiring diagram from the internal junction box. 220v is written in pencil and 440v is crossed out...kind of a head scratcher

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This is the external switching on the back of the lathe

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Data card inside external switch lid

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And the original lathe controls on the front of the machine which i would like to wire the VFD up to. It has forward/reverse function.

NtR1IlRl.jpg
 
The motor has only three wires, and therefore cannot be rewired for different voltages.

460V VFDs of reasonable quality can be had cheap because people buy up the 230V ones.

If you want cheap 440, find a transformer with primaries and secondaries anywhere from 208-240, and wire the input in parallel with and the output in series with the power supply. The output will add (or subtract if wired backwards) and roughly double your mains voltage. The transformer KVA rating must be more than half of what you intend to draw. It's not great, but it works fine.
 
My 1917 10 HP Westinghouse is 220/230/240 only on its three leads. Guess that was common over 100 years back

That reversing starter should say somewhere in its data what it is good for on 220/230/240. You can also check its coil voltage - if 220 there would have to be a transformer to run it on 440

This coil voltage will be on those "yellow" tags
 
My 1917 10 HP Westinghouse is 220/230/240 only on its three leads. Guess that was common over 100 years back

That reversing starter should say somewhere in its data what it is good for on 220/230/240. You can also check its coil voltage - if 220 there would have to be a transformer to run it on 440

This coil voltage will be on those "yellow" tags

That's not dual voltage, that's just a 230V motor that runs okay 10 volts over or under. Modern motors are commonly 208-230 rated. They just draw a bit more on 208.

His motor will not survive 440 volts.
 
The motor has only three wires, and therefore cannot be rewired for different voltages.

Thank you for confirming that.

So if re-wiring is not possible then I am inclined to go with swapping the motor out for a 220v of similar specs. With grasp and comfort level with electrical I would prefer not to mess with transformers.

Given a suitable 220v 3ph motor and VFD will there be any other major concerns with the existing layout? Will i need to do anything with the internal lathe junction box?

Here is a close up of the yellow tags on the coils. They read 220v25cy so I assume that would be the motor spec i need to look for at 220v?

HuDWvROl.jpg

Also i found this data plate between the two coils. It reads 440v 3ph 60cy.

Cdgi7Ovl.jpg
 
Thank you for confirming that.

So if re-wiring is not possible then I am inclined to go with swapping the motor out for a 220v of similar specs. With grasp and comfort level with electrical I would prefer not to mess with transformers.

Given a suitable 220v 3ph motor and VFD will there be any other major concerns with the existing layout? Will i need to do anything with the internal lathe junction box?

Here is a close up of the yellow tags on the coils. They read 220v25cy so I assume that would be the motor spec i need to look for at 220v?

View attachment 307212

Also i found this data plate between the two coils. It reads 440v 3ph 60cy.

View attachment 307213

Yes, you will ditch all of those contactors. Wire the forward, stop, and reverse buttons to the VFD control connections directly.

Some people, including myself, are not fond of working on a lathe chuck while it still connected to a powered drive. The chances of accidental activation are slim, but the consequences are significant. I recommend buying a "magnetic starter" to put between the incoming line power and the VFD that shuts everything off cold. It also functions as a true E-stop, because VFDs don't actually have proper emergency stop functionality.

Surplus Center carries a Hitachi 3hp VFD designed for single phase input. I bought one and used it on a cold saw a while ago. I can dig up the link if interested.
 
Yes, you will ditch all of those contactors. Wire the forward, stop, and reverse buttons to the VFD control connections directly.

Some people, including myself, are not fond of working on a lathe chuck while it still connected to a powered drive. The chances of accidental activation are slim, but the consequences are significant. I recommend buying a "magnetic starter" to put between the incoming line power and the VFD that shuts everything off cold. It also functions as a true E-stop, because VFDs don't actually have proper emergency stop functionality.

Surplus Center carries a Hitachi 3hp VFD designed for single phase input. I bought one and used it on a cold saw a while ago. I can dig up the link if interested.

Excellent! I will keep doing my homework and post my results once i have figured everything out.

Thanks everyone for the help.
 
Some VFDs with a so-called 'safe torque off' (STO) functionality are rated to absolutely not start without the safety inputs present, and to immediately stop applying power/torque when the safety signal is removed.

It is important to remember that the same issues can apply with contactors, although usually what happens is they weld closed and then don't open when you hit the stop button.

Start buttons can also fail or be bumped, and shock/vibration can cause a contactor to bounce closed and then the holding contact will hold it there.

The standard on most modern machinery is two safety contactors in series, monitored by a safety relay that is also monitoring e-stops and guards, plus the normal per-motor controls. Or the above but with the VFD's redundant STO in place of the contactors.
 
Some VFDs with a so-called 'safe torque off' (STO) functionality are rated to absolutely not start without the safety inputs present, and to immediately stop applying power/torque when the safety signal is removed.

It is important to remember that the same issues can apply with contactors, although usually what happens is they weld closed and then don't open when you hit the stop button.

Start buttons can also fail or be bumped, and shock/vibration can cause a contactor to bounce closed and then the holding contact will hold it there.

The standard on most modern machinery is two safety contactors in series, monitored by a safety relay that is also monitoring e-stops and guards, plus the normal per-motor controls. Or the above but with the VFD's redundant STO in place of the contactors.

That's pretty neat. I looked it up and the typical method is to disconnect the IGBT gate inputs so no signal can get to the transistors. That also means that even though an IGBT can fail shorted, that will cause the motor windings to be live but will not cause the motor to rotate. Interesting stuff.

My typical approach to safety equipment is to have all safety outputs in series with a common safety line, signalling to the main safety contactor and to all drives to stop. I like the double contactor approach.

The one pet peeve I have with emergency stops is when they shut off the controls and computer too. In an actual emergency I may need to reset the E stop immediately and jog the machine one way or another. Not to mention the consequence of loss of data/program origin/crashing of turbopumps/ etc may make the e-stop button seem too drastic of an action for a scenario that could otherwise use it (such as an imminent laser head crash).

Not all of this was relevant to the machine the thread was made for, by the way.
 
by the looks of the inside of that motor with the insulating paint i would say it has been rewound at one time and being more then likely the other owner only interned to run it on 440 why pay for the cost to have it rewound for 220 / 440 and specking of 440 we think we have a tough time with 220 3 ph cheek out what the limeys have to put up with to get 220 / 440 3 ph with a rpc in there home shops on there tru 220 two wire 1 ph. there only a third of the way there as we are two thirds of the way there with are 220 three wire 2 ph. but whatever way you go good luck with your quest
 
That's pretty neat. I looked it up and the typical method is to disconnect the IGBT gate inputs so no signal can get to the transistors. That also means that even though an IGBT can fail shorted, that will cause the motor windings to be live but will not cause the motor to rotate. Interesting stuff.

My typical approach to safety equipment is to have all safety outputs in series with a common safety line, signalling to the main safety contactor and to all drives to stop. I like the double contactor approach.

The one pet peeve I have with emergency stops is when they shut off the controls and computer too. In an actual emergency I may need to reset the E stop immediately and jog the machine one way or another. Not to mention the consequence of loss of data/program origin/crashing of turbopumps/ etc may make the e-stop button seem too drastic of an action for a scenario that could otherwise use it (such as an imminent laser head crash).

Not all of this was relevant to the machine the thread was made for, by the way.

Gentlemen...I have pretty much no idea what you are talking about. Which makes me feel like i have come to the right place :cheers:.
 
Okay i've been reading and researching I think I am pretty close as far as components for the power system with the exception of scaling ratings up/down. Here is what i have so far:

**In lieu of a sweet wiring diagram here is the flow as best i can explain it as it comes out of the wall until it spins the lathe**

COMING OUT OF THE MAGIC HOLE IN THE WALL

1. Power source 220v 1ph

10awg 220v rated cord and plug -----feeds> ENCLOSURE

2. MCB 2 pole @ 12A -or- 30A
- Do i go 125% of the motor max amp draw of 9A? Or go off of the feeder line breaker of 30A?

3. Mag Starter NEMA 4x @ 3hp and 9A w/ Start/Stop/Reset
- I was considering wiring a remote pushbutton station located at the stock lathe control location. Is this dumb?

4. 2 pole Inline fuses rated for 3hp 230v Single phase input
What amp rating? Higher than the MCB right?

5. VFD - Teco L510 220v 1ph input ---> 220v 3ph output

6. Shielded 14awg cable from VFD to motor

7. Shielded 20awg multi conductor cable from VFD to stock lathe control location
-I still need to work out the control button setup. I want to use the stock lathe control location for everything if feasible and sensible.

Buttons for:
VFD Start/Stop
FWD
REV

Mag starter start/stop (i would not put the reset function at the remote station)



Got my motor back today from being re-wound. I had it setup for multiple voltages just in case.

vRFlDapl.jpg

This is my original set of AB control buttons. I think they are still in good shape and could be re-used potentially. Are these normally open or normally closed type switches?

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This is my first project of this type so go easy fellas!
 
You can probably reuse the switches. Chances are the stop is normally closed and the start is normally open. Confirm this with a meter.

The breaker in the panel protects the downstream wiring. The breaker in the machine protects the machine. Size it to the load, but make sure you consider starting load (smaller with a VFD) and VFD efficiency.

Once you pull and measure those switches, and decide what functions you want, we can help you wire them.

The ingredients look fine. Check that the Teco has enough inputs to control how you want.
 
There's no point in having two breakers and a fuse switch protecting the drive.

Replace the breaker with a fuse switch containing fuses as per the drive manual, or omit altogether - in theory it increases the chance of parts of the drive surviving (because fuses can operate faster in some cases) if other parts of it fail, which is IMHO only worth it for quite expensive drives where you would actually do piecemeal repairs. The manual seems to say either a fuse or breaker is adequate; they recommend 50A fuses if you use fuses.

It's on a plug so you could omit the switch, although I'm in the land of switched sockets so you may want a switch on the machine as well/instead.

Line current is given as 21A so you're not going to want to go any lower than the 30A MCB.

It appears the Teco doesn't support FWD/REV/STOP buttons for some reason, so you'll need a pair of latching relays assuming your buttons are momentary.

Alternatively, you could either use a switch for FWD/REV, or just two switches. There is a software setting to disable restart on power on even if it immediately receives a start signal, plus your contactor will also protect against automatic restart after power failure.
 
Okay i got everything hooked up! Test runs are completed.

I just used the mag starter and omitted the MCB. Minus my external controls and some cleanup wiring i am very close. Going to get things more organized with some terminal blocks. Used a pelican case for the enclosure. Going to add a little plexi window to it and some venting up top. If i am endangering the neighborhood with this let me know...

GHeIcwyl.jpg

I think the best setup for me will be controlling the VFD via the following:

Start - N.O. Push Button
Stop - N.C. Push Button

Two position rotary switch to control fwd/rev

Is that feasible? If so the only thing left for me to figure out is how to actually wire it...i went ahead and picked up a 12 conductor shielded control cable so i should have enough conductors to cover all that...i think. Thoughts?
 
Okay i got everything hooked up! Test runs are completed.

I just used the mag starter and omitted the MCB. Minus my external controls and some cleanup wiring i am very close. Going to get things more organized with some terminal blocks. Used a pelican case for the enclosure. Going to add a little plexi window to it and some venting up top. If i am endangering the neighborhood with this let me know...

View attachment 310476

I think the best setup for me will be controlling the VFD via the following:

Start - N.O. Push Button
Stop - N.C. Push Button

Two position rotary switch to control fwd/rev

Is that feasible? If so the only thing left for me to figure out is how to actually wire it...i went ahead and picked up a 12 conductor shielded control cable so i should have enough conductors to cover all that...i think. Thoughts?

I would personally space the VFD off of the back a little bit and put a vent near the back on the top and bottom of the box to improve airflow. Shroud the top vent to minimize stuff falling into it. If you cut something like a 1/2" x 4" slot for example, an easy way to shroud it is to mount a 1 1/2" x 6" or so plate above the slot spaced off a half inch.

I haven't read up on the exact VFD so I can't comment on the connections, but the NO/NC setup like that is pretty common. So long as you have the inputs and can program the functions you should be fine.

Make sure you don't have a cold plate type VFD, meant to be mounted to a heatsink.
 
Okay so based on my plan i am going to attempt to wire up my switches according to this diagram for 3-wire control. Is it actually as simple as it looks? A few jumpers between the switches and terminate the rest at the appropriate location?

T6JQ6HTl.jpg
 
Okay so based on my plan i am going to attempt to wire up my switches according to this diagram for 3-wire control. Is it actually as simple as it looks? A few jumpers between the switches and terminate the rest at the appropriate location?

View attachment 310588

Correct. This way looks a little funny just so stop overrides start, in the event of a short or something.
 
Got it done! Thanks team! I used a 3 position switch for the fwd/rev. Only thing that puzzled me is that when switched to the "off" position it will still run forward when i hit the "start" button...i used the normally closed side of the selector for whatever thats worth.

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