Another wiring question

[Shaun @ Tru6]

I just picked up this buffer and am a little confused on how to wire it for power. As you can see the power line is cut as is the foot pedal but that's easy to reconnect. The shop I bought it from was too busy moving and the guy who knew about it was let go in the move so all I have is "it works."

Motor is 3 phase, 3 hp 208-230.

The junction box has the deadman pedal and wire going out to plug it in. The deadman pedal has 3 heavy gauge wires but the green is just clipped inside the box. The plug wire is just 2 wires. that doesn't make sense to me except the black label just above the connectors says 120V. They think it was cut because it was just wired into the breaker box.

Any ideas how it should be wired if it isn't properly? It was used a lot.

[1990C4S]

Looks like the foot pedal pulls in the contactor...

[billybek]

Is the coil voltage on the contractor 120 vac?
Not saying this is the right thing to do but it appears that they may have had 120vac supplied as control voltage from a wall outlet. Two switches in series on/off on the front and the foot pedal, both n/o switches need to close for the contractor coil to be energized, and allowing the motor to start.

[Paul_Heery]

Do the drawings from the manufacturer help?

https://www.baldor.com/catalog/1252#tab=%22drawings%22

[Pazuzu]

When they wired in the foot pedal, they had a length of 3-wire SOW cord laying around and used it instead of going out to buy some 2-wire cord.


As for the motor, it could also be 3 phase 460/480V unless you know they ran it on 220V. It's a standard Baldur 3 phase, dual voltage motor, there are millions of them out there. There should be a plate that you can open up, there will be 9 wires inside, they *should* be numbered, and they will be linked together in 3 or 4 groups. That is how you go between 230V/ 460V, Wye or Delta configuration.

So, is your shop 220/230V, and is it Wye or Delta? When you probe the L1/L2/L3 wires, is there 208V between each and every phase, or is it 240V between each phase? Is there a neutral wire? Is it 120V between each phase and neutral, or is it 120/120/208V?

[Shaun @ Tru6]

Originally Posted by Pazuzu

When they wired in the foot pedal, they had a length of 3-wire SOW cord laying around and used it instead of going out to buy some 2-wire cord.


As for the motor, it could also be 3 phase 460/480V unless you know they ran it on 220V. It's a standard Baldur 3 phase, dual voltage motor, there are millions of them out there. There should be a plate that you can open up, there will be 9 wires inside, they *should* be numbered, and they will be linked together in 3 or 4 groups. That is how you go between 230V/ 460V, Wye or Delta configuration.

So, is your shop 220/230V, and is it Wye or Delta? When you probe the L1/L2/L3 wires, is there 208V between each and every phase, or is it 240V between each phase? Is there a neutral wire? Is it 120V between each phase and neutral, or is it 120/120/208V?

All good information and questions. I will report back tomorrow morning. I think there is 208 in between each phase but will confirm.

[carambola]

I have nothing to add, all great observations and advice.

[Pazuzu]

"Wye" style 3 phase is symmetric between the phases, and what is in "modern" industrial buildings.
"Delta" style has a hot, or wild phase, which is higher potential compared to the other 2 phases, this makes it easier to get all sorts of single phase voltages in one building (120, 208, 220). Old industrial buildings use this.

I *think* you're in an old building, but if someone came in and updated it, all bets are off.

Don't blow your hands off testing the voltage between the phases.
If there is an orange wire, or a wire with orange electrical tape on it, then you have a wild leg delta, it's industry standard to label the wild leg as orange. In 480V feeds, that wild leg is 277V to ground, which is enough to maim or kill, so that's why they're careful to label it.

[Shaun @ Tru6]

Here is what I have, I hope this helps in trying to figure out how I can plug the buffer in. Used a Fluke multimeter across the terminals at the breaker box and then inserted into the sockets for the wall plug for the air compressor. A buck boost transformer plugs into the wall to give it the 230V it wants. Also a pic of the box on buffer.

[1990C4S]

You need the three phases from the transformer (top pic). And probably one phase to neutral for your foot pedal/coil circuit...

And you need the motor windings configured to 208/230.

[Shaun @ Tru6]

Thank you. A few questions:

How can I find out what the motor windings are currently configured at? The deadman pedal is rated for 125 to 250 VAC so would that indicate it's set for 208-230V?

And I think I figured something out. Here's a pic again for the box that connects the deadman pedal to the buffer. I was told the buffer will only work when the pedal is pressed. It will rip your arms off otherwise if a sleeve or something gets caught.

The top of this box where a conduit elbow screws in there are 3 screws that are loose and scratch marks in the dust. this must be where power goes in. So I think there is only the one mystery wire that is clipped.

[Arizona_928]

Just plug and play. Those old wires at the bottom of the 3 phase switch looks like old 120v house wiring. Noticed the white and black switched to i assume the pedal?

Pull the cover on the motor you should have 3 or 9 wires. Make sure you check rotation of the motor once you get everything running too.

[billybek]

Compare the number tags to t he wiring diagram. This is not a wye delta motor. It is a wye wound motor and the star point is not accessible. High voltage config places two (correct) windings in series for each of the three phases. Low voltage is like two wye wound motors connected in parallel.
Is the coil voltage 120? If you bring in a neutral leg any one of your three phases will suffice as a control voltage. Make sure that all the components are grounded properly.
Forgot you were on a single phase service. Ymmv.

[dad911]

https://www.baldor.com/catalog/1252#tab=%22specs%22

Connection diagram under the 'drawings' tab.

As Arizona said above, motor connections are usually near or under the plate where the wires enter the motor.

[1990C4S]

The foot pedal voltage is irrelevant, that's the rating. What voltage is the coil on the starter? I think I see 110V.

[Shaun @ Tru6]

[Shaun @ Tru6]

OK, it looks like I have one of two options to get this thing going.

Buy a phase converter so I can run the 3 phase motor on my single phase system. Found these: Need A Variable Frequency Drive To Run Your 3 Phase Motor On Single Phase Power?

https://www.precision-elec.com/shop/?filter_product-category=vfd-static-phase-converters&filtering=1&filter_input-voltages=240-vac-input

See relatively inexpensive.


Second is more of a question than an option. Since there is 3 phase coming into the breaker box, can I have an electrician install a 3 phase breaker box next to our single phase one? And then run the buffer off that?

Clearly if the first will work, it's the best option but am interested in opinions on the second.

[Zeke]

I think It would be better and cheaper to run a dedicated 3-phase circuit to the buffer. I'm surprised you don't have more 3-phase power distributed throughout your shop. Much more efficient for ovens, etc.

[dad911]

VFDs are nice. We used to remove and toss the 3 phase motors from lathes and milling machines to wire them for home use. Now I'd slap on a VFD and get variable speed as a bonus.

I just went back to this thread: Why is this breaker failing so quickly?

I'm confused about your power.......


3 breakers, but:

Originally Posted by Shaun @ Tru6

phase to phase is 211V. When I called Nstar a few years ago they were very clear that I had single phase 208V.
....

[Shaun @ Tru6]

Here's our internal breaker box with the front cover removed. From the diagram above we have 208/205/208 across all three terminals.