Converting Compressor motor from 220 v to 110 v

[Oren]

I have a 5 HP, 1989 Craftsman Air Compressor (Model NO. 919.176851). It's a 240 Voltage Single Phase motor made by General Electric. My question is: can I convert this to a 110v use by changing the plug-cord assembly only? Will this motor run on 110v without damage to it? Or am I stuck with having to stay with the 220v configuration.

Thanks,

Oren "My doctor says I have a malformed public-duty gland and a natural deficiency in moral fiber, and that I am therefore excused from saving Universes."

[Bob]

If the motor gives dual voltage on the name plate, then you can. If not, then you can't.

[SQLit]

Unless the motor is dual voltage your stuck with 240 v. There are motors that can have the interior wiring configuration changed or the taps where the wires land are set up for dual voltage. Read the name plate and then google the motor.

I am amazed that you thought that changing the plug would even work. Sorta like changing the tires on a pinto and getting a T-bird.

[TKM]

The nameplate on the motor is the place to look. Some motors are dual voltage and the nameplate will have a wiring diagram or other information about how to change the voltage. Simply plugging a motor set for 240 volts into a 120 volt outlet will not work. It won't be able to put out the power needed to operate the compressor -- if it starts at all.

TKM

[Toller]

Real 5hp motors couldn't be run on 120v. Well, they could, but would draw

[mm]

Maybe you could get a T-pinto?

Remove NOPSAM to email me. Please let me know if you have posted also.

[Edwin Pawlowski]

Halving the volts will double the amps. You will need a special circuit to handle the load as it will pull far more than normal house circuits can handle. . There is no benefit to change it over and many reasons to leave it at 220.

The motor may or may not be capable of running on 120V. You have to check the nameplate for specifications and the wiring that has to be changed internally.

[Oren]

I've checked the motor plate:

It's a one speed motor v230, 60 Hz and 13.1 A (Amps?) . There is no mention of "dual voltage".

I did find a diagram under the switch housing, but nothing to indicate capability to wire another configuration. It (reminded me of the wiring for a GFCI) had - lines IN (plug cord) and lines OUT (motor cord).

The manual indicates a minimum branch circuit of 15 amps and " This compressor can be operated on a 15 amp circuit if: voltage supply to circuit is normal, circuit is not used to supply any other electrical needs (lights, appliances, etc. ) and extension cords comply with specifications".

It goes on that if these conditions cannot be met a 20 amp circuit may be necessary. "It is not necessary to change the cord set if this change is made".

Thanks,

Oren "My doctor says I have a malformed public-duty gland and a natural deficiency in moral fiber, and that I am therefore excused from saving Universes."

[Edwin Pawlowski]

You will have to leave it at 220 then. At 13A it is borderline as on startup it will pull much more. If you don't have a circuit now, I'd size it for 20A and be done with it.

[Oren]

Thanks.... I guess it stays @ 220V.

Oren "My doctor says I have a malformed public-duty gland and a natural deficiency in moral fiber, and that I am therefore excused from saving Universes."

[Sam]

replying to SQLit, Sam wrote: Actually, some 240v motors can be safely run on 120 or 110, but would probably lack the power necessary to start the motor turning from full stop. It would be more like putting a little battery in a big truck. It might be able to bump start, but it is doubtful that it would be able to turn over the engine due to the lower voltage. So, in some cases, simply changing the plug and adding in a manual pull start to turn the rotor will allow a 240v machine to operate properly.. The problem lies with the phases of electricity you are getting. 240v is two alternating phases of 120v. it is possible to wire a 240v outlet using 2

120v lines with opposite phases. A capacitor generally plays the role of "bump starter" for 120v machines (by providing that second phase emulating 240v electricity and turning the motor over the first time) and is why the wiring needs to be changed. After that there is very little difference in the performance of 240v and 120v. It is an instant at the start and matters very little after that. Note, the same thing in reverse is not possible. If you plug a 120v motor into a 240v outlet, then you will have and immediate and serious problem. You should try to be less demeaning to others SQLit. There is no point in being rude and condescending because someone isn't educated about voltage and wiring.

[#1]

You'll need one of those magic transformers that turns a single-phase input on the primary into a two-phase output on the secondary.

[Ralph Mowery]

Outside of this being around 10 years old, the above is very missinformed advice. The motor would be wired as a single phase 240 volt motor, not some kind of 2 phase 240 volts. I doubt that one would be hard pressed to find any 2 phase in use in the US unless some very old factory.

No point in being rude to you as you don't seem to be educated about voltage and wiring.

[Sam E]

No transformer needed. TWO single-phase lines from the same source (already 180 degrees out of phase, as needed here).

Now, maybe you can figure out how to get 3 phase.

[clare]

If it is a dual voltage motor (which most medium sised compressor motors are) you just need to switch the wires in the motor and change the plug. HOWEVER the compressor will require twice the amperage at half the voltage, so unless it is smaller than 2 real horsepower it will NOT run on a 15 amp circuit, and will quite likely trip a 20 amp on starting. (which is why I switched MINE from 120 to 240 volts)

There is no "phase issue" at all. There is no such thing as "two phase" power, at least not in common North American use. All 120 volt power in north american distribution systems is derived from center tapped 240 volt single phase transformers except in a 3 phase distribution system, where you get 120 and 208 (120 across 1 phase, and 208 across 2 phases of the 3 phase supply).

[Bill]

Here, it's either single-phase or 3-phase. No two-phase is available.

Single-phase 120/240 service is delivered from a standard ubiquitous center-tapped transformer.

The 3-phase wye service is 120/208 and the phases are 120 degrees apart.

[Dean Hoffman]

The REAs in rural Nebraska also supply three phase power to irrigation well motors. I've seen center tap delta which is basically double what you referenced. There is the Y configuration, 277 volts each line to ground. Lastly is the corner ground delta. Two lines read

480 to ground, the third line reads 0 to ground. All of those read 480 line to line. Some grain bin drying systems are wired with the three phase you mentioned. That lets the electricians use common 120 volt controls. There is also enough power with the three phase to run drying fans.

[clare]

That is true - there are MANY other "industrial" voltages - and 3 phase Delta or wye . However, in "residential" systems, except in some larger MURBs, it is exclusively 120/240. In those MURBs, 120/208 3 phase..

All this "non-standard residential" has NOTHING to do with converting a 240 volt compressor to 120 volts - because ALL 240 volt systems - even in europe behave the same (with the exception it may be 50hz instead of 60) and a motor connected for 220/240 will work on any 60hz

240 volt circuit. By reconfiguring for 120 volts it will require twice the amperage. If, in the extremely unlikely case, the motor is 240 volts only and can not be reconfigured, the cheapest solution (and simplest in most cases) is a replacement motor (assuming a belt driven standard compressor - not too many 240 volt integrated oil-less compressors on the north american market) If this is a european market compressor brought to North America, all bets are off.

[gfretwell]

I have also seen 240v 3p corner delta, usually feeding sewer lift pumps. It is pretty strange the first time you see it because it is 3 phase with only 2 ungrounded conductors so it looks like single phase. (2 black wires and a white on a 2 pole breaker)

[clare]

With 3 phase motors? Requires 4 wires for a 3 phase motor on corner delta. Sounds more like single phase 208. - because theree are generally only 2 ungrounded wires in a corner delta (which is no longer allowed, to the best of my knowlege, in Ontario) - and with corner delta 3 phase you have no 120 without a transformer - and generally no center-tapped transformer is used (which is generally why grounded delta was used - to avoid the requirement for a more expensive center tapped transformer) Means you can't use a 240 device that has 120 volt controls without installing a "control transformer" on each device.to supply the required 120 volts.