Electrician Help **Powering up 3 phase machines on single phase**

[Big D]

Need some input on wiring up some 3 phase machines in a garage with single phase power.

After 65+ years in business as a Tool & Die maker, my pop is finally calling it quits. We are liquidating all the equipment, but he is holding onto a Bridgeport mill & an Engine lathe. I'm Trying to set him up with a small hobby shop in his 3 car garage. Both machines are 3 phase power so I'm looking for input on how we can set them up to run on single phase power. I know we'll need to run some type of phase converter, but I have no education on how it all works. I believe the mill is 2 HP & the lathe is 7.5 HP. He has a 100 amp panel that is full but he does have a 30 amp service going to a RV plug which he does not use. If it's feasible, looking to get this done ASAP. Any input would be greatly appreciated.

 

[bonesfab]

Get a VFD. my buddy just did a mill and lathe at his house with them.

 

[fmo24]

There are a bunch of smart peeps in the machine and fab forum that can give you some direction

 

[Livewire Fabworks]

VFD. I run a 3 phase mill and a 3 phase lathe in my garage on VFD's. No complaints.

 

[Shlbyntro]

a lot of 3phase motors can be wired to run on single phase 220v. you'll lose some HP but it'll work and last. most will have the various wiring diagrams under an access lid on the motor itself

 

[Rayson1971]

Get a phase converter probably cheaper. I have one for my mill

 

[Rayson1971]

 

[WYRD]

View attachment 1099681

This will be your most cost-effective solution. Vfd is nice but overkill if you don't need all the features

 

[Big D]

Thanks for all the feedback

 

[Big D]

Think it's feasible with the 100 amp service & running off the existing 30 amp breaker? Hoping to drop the machines on the floor next week and can figure out all the details after. Just don't want to find out later that I don't have ample power to support the machines.

 

[Racey]

a lot of 3phase motors can be wired to run on single phase 220v. you'll lose some HP but it'll work and last. most will have the various wiring diagrams under an access lid on the motor itself

Not on machinery. With no starter you can't guarantee the motor would run the proper way each time. It's also a good way to burn the motor up as the torque is massively limited when you single phase a three phase motor. I've never seen a machine tool in my life with a starting cap on the motor. What you may be thinking is that most 3 phase motors can be wired for dual voltage (220/480) not single and three phase.

VFD for single phase essentially needs to be rated at twice the power of the motor (it's actually 1.77 iirc) so a 2hp motor needs a 4hp drive to run on single phase.

VFDs are very affordable now and offer many features and benefits over a phase converter, including speed control and better power factor.

 

[WTR&PWR]

I think 30A is gonna be close for you on the lathe. 7.5HP x 746 watts per horsepower =5,595 watts. Now divide that by your single phase 240v and it’s drawing 23+ amps plus any other loads you are running off it including for Whatever the load is of the VFD itself.

 

[Your ad here]

I think 30A is gonna be close for you on the lathe. 7.5HP x 746 watts per horsepower =5,595 watts. Now divide that by your single phase 240v and it’s drawing 23+ amps plus any other loads you are running off it including for Whatever the load is of the VFD itself.

I think the math for 3 phase is volts x amps x 1.73 = watts.
7.5hp 3 phase 1770rpm motor should be 240 volts and 18 amps.
240 volt x 18 amps x 1.73 = 7,473.6 watts.
7473.6 watts/240 volts single phase = 31.14 amps

Single phase is volts x amps = watts.

 

[Roosky01]

I thought 3-phase was when you had three drop cords plugged into a three way splitter?

P.S. I don’t know shit about electricity….

 

[Your ad here]

I do know for a fact a 240 volt/29amp 7.5hp single phase 1770rpm motor can start and run off a 30 amp breaker. I've ran the motor at up to a 35 amp load for short periods and didn't trip the breaker or melt wires. Toughest part is figuring out the motor starter. The whole starting assembly is 3 times larger than the motor starter for my 480 volt 15hp 3 phase motor.

 

[scottchbrite]

Here is a thread on another forum that might be helpful.

Show us your VFD conversions/installations

I'm a pretty techie person and love this stuff. I have worked with VFDs in my customers machines for many years but never took the time to understand them enough to do my own installs. For some reason, I thought that they were a lot more involved in the configuration aspect. Now that I have dug...

www.garagejournal.com

 

[jmeads]

View attachment 1099681

This is what I did in my garage. It powers 2 - phase 3 machines.

 

[lbhsbz]

Think it's feasible with the 100 amp service & running off the existing 30 amp breaker? Hoping to drop the machines on the floor next week and can figure out all the details after. Just don't want to find out later that I don't have ample power to support the machines.

Yes. You need about 7 amps/hp/phase. Your lathe should draw about 18 amps.

It doesn’t sound right, but look at the wire size coming off the contactors to get a better idea of current requirement…it ain’t much.

Keep in mind that each 3pH motor needs its own VFD. My mill has a Y axis power feed and a spindle motor…so 2 VFDs required to run it.

 

[WTR&PWR]

I think the math for 3 phase is volts x amps x 1.73 = watts.
7.5hp 3 phase 1770rpm motor should be 240 volts and 18 amps.
240 volt x 18 amps x 1.73 = 7,473.6 watts.
7473.6 watts/240 volts single phase = 31.14 amps

Single phase is volts x amps = watts.

You are correct but I was talking single phase 240v. I think when you’re calculating motor load (like HP) your 3 phase multiplier (either phase voltage x3 or phase to phase voltage x1.73) is already factored so converting to watts is as simple as 7.5x746=5,595 watts require to power on a 7.5hp motor. If you plan on running that off single phase 240v then it’s as simple as 5,595 watts/240v= 23.3125 amps. This really isn’t my specialty but just trying to lend a hand. Correct me if I’m wrong.

 

[Boat Anchor]

Need some input on wiring up some 3 phase machines in a garage with single phase power.

After 65+ years in business as a Tool & Die maker, my pop is finally calling it quits. We are liquidating all the equipment, but he is holding onto a Bridgeport mill & an Engine lathe. I'm Trying to set him up with a small hobby shop in his 3 car garage. Both machines are 3 phase power so I'm looking for input on how we can set them up to run on single phase power. I know we'll need to run some type of phase converter, but I have no education on how it all works. I believe the mill is 2 HP & the lathe is 7.5 HP. He has a 100 amp panel that is full but he does have a 30 amp service going to a RV plug which he does not use. If it's feasible, looking to get this done ASAP. Any input would be greatly appreciated.

I have the phase converter system that you are asking about in my garage/shop. I power a 2 HP Tree 2UVR vertical mill, a Takisawa 5 HP T 800 lathe, a Delta 3/4 HP belt sander, and a Apex 16 inch 2 HP disk grinder, with a 10 HP 3400 RPM rotary phase converter. Since I am the only person operating my machines, I never have more than one machine running at a time. I have been using this system for over twenty years, and have never had a issue with it. I purchased my phase converter from a guy in Norwalk Ca. who built them in his garage/shop from new components that he purchased from Grangers. It is built from a 10 HP 3400 RPM 3 phase motor, and has a 8" x 8" electrical box mounted to it containing 3 separate relays, and a starting capacitor. I have a fused disconnect with 220 single phase coming into it which runs up to my phase converter. When I switch the disconnect box to on, the single phase power travels up to the the electrical box on the phase converter with the relays and starting capacitor, which starts the 10 HP 3 phase motor. Once the 10 HP 3 phase motor is running it acts as a 3 phase generator, and it's output is wired to each of my 3 phase machines. I just walk up to the machine that I want to run, switch it on and and go to work. It's that easy. With the rotary phase converter, your machines will develop their full rated HP, where as with a static phase converter (non rotary) your machines will loose 1/3 of their rated HP (example, 1 1/2 HP Bridgeport mill will only develop 1 HP). It's a great system, and exactly what I think you are looking for. I am in Simi Valley, Ca. You are welcome to come by and check out my system.

 

[RiverDave]

I have a full phase converter setup in my garage..

There is a member here that sells them!

 

[Big D]

Thanks for all the input. If there is anybody on here that sells the phase converters or an electrician for hire that could assist me with setting these up, please let me know.