tmad13
New member
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- Santa Cruz, CA
How can i wire three phase motor with single phase power.
motor has nine leads
motor has nine leads
wire three phase motor with single phase power
- Thread starter tmad13
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- Chapel Hill, NC
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- Retired Electrical Contractor
You need to get a phase converter
Without a rotary phase converter, variable frequency drive, that accepts single phase input, or a static phase converter, 3 phase power will be required to run the motor.
- Location
- San Francisco Bay Area, CA, USA
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- Electrical Engineer
Well, technically you could WIRE a 3 phase motor with single phase power, it's just not going to run... :slaphead:
gar
Senior Member
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- Ann Arbor, Michigan
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- EE
180710-1633 EDT
If you mechanically start it rotating, and sufficient torque can be provided relative to load, then it will run
.
If you mechanically start it rotating, and sufficient torque can be provided relative to load, then it will run
.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
The cost of the motor when it burns up, plus the cost of down time while you replace it.Don't be giving out bad ideas... It will run but at what expense?
Craigv
Senior Member
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- Boyertown, PA, USA
Sell or return the 3ph motor, and buy the right motor for the available power and job it must do.
OldSparks
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- Vacaville CA USA
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- Retired: Electrician, Submarine Electronics (21 years), Potable water system maintenance boss (21 years).
I recently did this for a gent who has a 3-phase, 3HP lathe and wanted variable speed operation. We bought a Variable Frequency Drive that is designed to accept single-phase power and deliver 3-phase. At low horsepower, these are not really expensive. You can do the same with larger motors and drives, just be sure the drive is designed to handle the job the motor is expected to perform.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
The cost of the motor when it burns up, plus the cost of down time while you replace it.
and the time looking for your fingers...
hmy:
- Occupation
- Licensed Electrician
:thumbsup:
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
That's called a "pony motor" setup and will only work if the connected load requires no more than half of the motor's rated power. Giving single phase to a 3 phase motor that is already spinning is still severely unbalanced, The unbalance creates "negative sequence current" flowing in the rotor, which creates negative torque, "fighting" the torque the motor produces. So the motor heats up very fast under load even though the current in the powered phases may never exceed the FLA rating and can fry without ever tripping the OL relay. So if you had a 2HP motor but you machine only needed 1HP, it could run like that for a long time. But if the machine needed 2HP, it could fry the motor in a matter of minutes.
Frank DuVal
Senior Member
- Occupation
- Electrical Contractor, Electrical Engineer
Of course a rotary phase converter is just a three phase motor running on single phase...... with some capacitors and/or inductors to help get it going and stay running!
Andy Delle
Senior Member
- Location
- Los Angeles CA
Of course a rotary phase converter is just a three phase motor running on single phase...... with some capacitors and/or inductors to help get it going and stay running!
True, but they still have the same issues that Jraef indicated. There are a few companies that make these commercially but they seem to be mainly sold to the consumer market for used machine tools in a home shop.
These days a small VFD can be had for less than $500. That is IMO, the safest solution as it provides true balanced three phase power. Not that is may matter much for a weekend shop but those rotary units are quite inefficient as well.
You can't. Don'#t even try it.
ggunn
PE (Electrical), NABCEP certified
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- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
That's what I was gonna say. The way the question was phrased made me think that the OP was looking for a simple solution to his problem, of which there are none.
drcampbell
Senior Member
- Location
- The Motor City, Michigan USA
- Occupation
- Registered Professional Engineer
I do hope everybody realizes this is a "my dad" story about Appalachian Engineerin' and getting lucky, NOT a recommendation.
If you don't need variable speed, put your three-phase motor on Craig's List and get a single-phase motor.
The monkey wrench in the works would be machine with a proprietary motor such as a direct drive motor having a custom shaft, in my shop are 3-1970's Rockwell machines with 3Ø motors, one a 7" grinder with a 200V motor that would be impossible to change, runs fine w/ a VFD* as do the other 2 and the one machine w/ another 200V motor is really the only one that could be changed but it was less then $200 for the VFD. In most cases where 3Ø is not avail., I agree that 1Ø is the best choice, sometimes though another method is better.
*The VFD was only $75.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
sure, I wouldnt do this, nor suggest anyone do this in a professional capacity. Might be ok for a hoppyist type of machine use and duty cycle.....
I was thinking about this and remembering a few more details. There is a trick to make it work much better. You can connect a second three phase "slave" motor in parallel with the master and this results in a much smoother and stable system.
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