DIY wiring a 3 phase compressor?

[GlennRobinson]

Basic question...

I just bought a large compressor for my shop. It requires a 3 phase connection. I can handle just about any "household" electrical work. Is installing a 3 phase connection something I should attempt or am I better off hiring an electrician?

If it is a DIY project, any advice or guidance?

Thanks,

Glenn

 

[jlv03]

Do you have 3 phase available? How big (HP wise) is the motor?

 

[DeeKay]

Need more info on your project.
What if any 3 phase supply do you have available? 208, 240 480?

 

[marinusdees]

3 phase power is not a usual power supply for a residence. So, you need to source a 3 phase source to convert your single phase. That being said, compressors in general do not like "phony" 3 phase sources. Not saying it can't be done, saying it is somewhat complex, maybe not cost effective. If the motor is 5 hp, it's better to buy a single phase 5 hp motor. The VFD boys can jump in.
Or, phase converter, stationary or rotary boys.

 

[Norcal]

Need more info on your project.
What if any 3 phase supply do you have available? 208, 240 480?

If 480V 3Ø definitely not DIY, the consequences of a mistake are too great.

 

[wyliesdiesels]

Basic question...

I just bought a large compressor for my shop. It requires a 3 phase connection. I can handle just about any "household" electrical work. Is installing a 3 phase connection something I should attempt or am I better off hiring an electrician?

If it is a DIY project, any advice or guidance?

Thanks,

Glenn

We definitely need more info here...

3 phase power is not a usual power supply for a residence. So, you need to source a 3 phase source to convert your single phase. That being said, compressors in general do not like "phony" 3 phase sources. Not saying it can't be done, saying it is somewhat complex, maybe not cost effective. If the motor is 5 hp, it's better to buy a single phase 5 hp motor. The VFD boys can jump in.
Or, phase converter, stationary or rotary boys.

Where did he say this is in a residence? he didn't. He said SHOP. Also, where did he say he has single phase power?

What is a "phony 3 phase source"? are you referring to a static converter?

 

[Mgraves235]

as others have chimed in, if you don't have 3 phase service coming into your shop, you CANT "wire it yourself"
your options are, a:have the power co install the service and b: purchase a vfd that allows phase conversion.
not to insult your intelligence, but i would recommend doing some homework and study before your next step.

back in the day, putting together a phase converter with a few extr motors was and option, and i've done it several times, but with the cost of motors being so high, and VFD's getting more affordable, it's not really an option anymore, unless you just happant to have access to electric motors. even then. they were marginal at best, and never a "proper" solution.

 

[MushCreek]

Many owners of rotary phase converters would disagree that they are 'never a proper solution'. I bought an American Rotary panel, driving a 10 hp idler motor. Plenty of proper three phase power. I paid $25 for the Baldor idler at an auction. Around here, three phase motors are dirt cheap at auction.

VFD's are a good option, but they require a little fiddling to be dialed in for the particular motor. I had one, but went to the RPC so I could run any motor, rather than buying a separate VFD for each machine.

As for wiring three phase, it's not all that hard, assuming you have it available. For each motor, hook it up and see if it runs in the correct direction. If not, reverse any two of the hot leads. The one big caution is if your three phase has a 'high leg' or 'stinger'. In many locations, one leg will be in the 220V range, with the other two legs being around 120V. My buddy baked the refrigerator in our shop because he plugged a single pole breaker into the high leg, feeding 220V to the poor old fridge.

 

[Chuckster in NJ]

Basic question...

I just bought a large compressor for my shop. It requires a 3 phase connection. I can handle just about any "household" electrical work. Is installing a 3 phase connection something I should attempt or am I better off hiring an electrician?

If it is a DIY project, any advice or guidance?

Thanks,

Glenn

Best Advice: HIRE a Electrical Contractor who has experience in doing this type of work.

BTW! NOT all electrical contractors have experience for your situation....... Trust me on this one!

 

[Norcal]

Many owners of rotary phase converters would disagree that they are 'never a proper solution'. I bought an American Rotary panel, driving a 10 hp idler motor. Plenty of proper three phase power. I paid $25 for the Baldor idler at an auction. Around here, three phase motors are dirt cheap at auction.

VFD's are a good option, but they require a little fiddling to be dialed in for the particular motor. I had one, but went to the RPC so I could run any motor, rather than buying a separate VFD for each machine.

As for wiring three phase, it's not all that hard, assuming you have it available. For each motor, hook it up and see if it runs in the correct direction. If not, reverse any two of the hot leads. The one big caution is if your three phase has a 'high leg' or 'stinger'. In many locations, one leg will be in the 220V range, with the other two legs being around 120V. My buddy baked the refrigerator in our shop because he plugged a single pole breaker into the high leg, feeding 220V to the poor old fridge.

The high leg is not "220V" it is 208V, not the same thing, but still lethal to 120V equipment.

 

[KenC]

The high leg is not "220V" it is 208V, not the same thing, but still lethal to 120V equipment.

In my shop the 'high leg' actually measures about 218 to ground. the other two are about 122 each. Even though I have it marked, still managed to wire a recept to the wrong pole and fried a modem power supply!

240v 3ph. Not 208/120 like newer buildings normally get around here.

 

[wyliesdiesels]

In my shop the 'high leg' actually measures about 218 to ground. the other two are about 122 each. Even though I have it marked, still managed to wire a recept to the wrong pole and fried a modem power supply!

240v 3ph. Not 208/120 like newer buildings normally get around here.

then your PoCo is running the primary a little hot. put some load on it and the stinger voltage will drop....

240v 3ph is delta connected and the algebra works out to 120/208/120, phase to neutral. The nominal voltage of the stinger/hi leg is 208v...

208v phase to phase is a different animal- Wye....

 

[laser3kw]

VFD's are a good option, but they require a little fiddling to be dialed in for the particular motor.

A lot of VFD's have "canned" programs that address certain reoccurring scenarios. The Yaskawas we use have a canned program for air compressors.

 

[nadogail]

IMHO, You are entering onto very thin ice for a DIY Electrican.

 

[alfredeneuman]

In my shop the 'high leg' actually measures about 218 to ground. the other two are about 122 each.

That's mathematically impossible.
1.732 is the multiplier (square root of 3) that is used.
122 X 1.732 =211.304

 

[Stuart in MN]

Before this wanders too far off topic, I'd wait for the original poster to come back and fill in some of the blanks before responding.

 

[wyliesdiesels]

That's mathematically impossible.
1.732 is the multiplier (square root of 3) that is used.
122 X 1.732 =211.304

his ungrounded conductors must be about 126v

 

[Bert_]

That's mathematically impossible.
1.732 is the multiplier (square root of 3) that is used.
122 X 1.732 =211.304

If there's a bunch of single phase load it's not uncommon to see more droop on those phases.

 

[DeeKay]

If 480V 3Ø definitely not DIY, the consequences of a mistake are too great.

That's why I asked
Though the consequences of not knowing what you're doing with anything over 50volts can be bad according to OSHA haha.

 

[GlennRobinson]

Wow! Thank you for all of the replies. Sorry for the delay in mine. I didn't have notifications turned on. (I do now.)

The compressor is a Ingersoll Rand 2545 with a 7.5hp motor. It calls for 200v 3-phase at 60hz.

We recently moved into a house that has two large garages that were used as an automotive sales and service business. One of the garages, I am making into my shop. There is separate power supply coming in for the two garages.

I do not see anything that would indicate a 3-phase power source. I am assuming I will need a phase converter or some other option.

Based on the replies so far, it looks like I am hiring an electrician with commercial/industrial expertise.

Glenn

 

[GlennRobinson]

Or maybe I should convert to single phase? I see reasonably priced single phase 7.5hp motors available for reasonable prices.

 

[Norcal]

Unless you have 208V power, the motor will need to be replaced or buck/boost transformers installed to buck the voltage down to the voltage range the motor is designed for, posting photos of the electric service will allow us to know what you have & then go from there.

 

[GlennRobinson]

Here is the main panel where the street power comes in.

But that is in the other garage. Here is the main panel in the Shop.

And there is another panel in the room that will house the compressor.

 

[DeeKay]

Unless you plan on buying other 3 phase equipment (mill, lathe, etc.) I think your best bet would be to skip the phase converter and just buy a single phase 7-1/2 horse motor or a decently priced VFD. Motor replacement would likely be the easiest/cheapest route though.

 

[DeeKay]

Unless you have 208V power, the motor will need to be replaced or buck/boost transformers installed to buck the voltage down to the voltage range the motor is designed for, posting photos of the electric service will allow us to know what you have & then go from there.

200v motors run fine on 208. My understanding is that they came out with 200 volt motors to run specifically on 208 rather than using a 208-230/460 motor which generally won't meet name plate specs at 208.

 

[GlennRobinson]

Unless you plan on buying other 3 phase equipment (mill, lathe, etc.) I think your best bet would be to skip the phase converter and just buy a single phase 7-1/2 horse motor or a decently priced VFD. Motor replacement would likely be the easiest/cheapest route though.

At some point, maybe, but not in the near future. So, what am I looking for in a single phase 7.5 hp motor? And what other challenges will I have to overcome to make the conversion?

Thank you,

Glenn

 

[nadogail]

That's mathematically impossible.
1.732 is the multiplier (square root of 3) that is used.
122 X 1.732 =211.304

IMHO, you have a Delta connected system and you have found the "Wild" leg witch , again in my opinion, should be marked with Orange Tape and not used for a 120 feed.

I made that mistake once and a grocery store with a previously unidentified Delta system lost their Radio/PA system.

THeir panel had a lot of Orange tape added into it when I finished that Baler Installation.

 

[Norcal]

200v motors run fine on 208. My understanding is that they came out with 200 volt motors to run specifically on 208 rather than using a 208-230/460 motor which generally won't meet name plate specs at 208.

If you had read my post I wrote that unless he had 208V the motor would need to be replaced or buck/boost transformers would have to be used, but since the OP’ s photos show single phase panels, we have to assume no 3 phase so a 7.5 HP single phase motor would be the best choice in my opinion but the existing mag starter may not be able to handle a 7.5 HP single phase motor.

200V is the rated voltage for 208V, like 230V motors are used with a 240V supply, compressors are frequently supplied with a single voltage 200V motor when they are run on 208V rather than a 200-230/460V motor.

 

[DeeKay]

You will want to match frame size, most likely 213 or 215...maybe 184
Synchronous speed(RPM)
TEFC or ODP; doesn't really matter but ODP is generally cheaper.
.....

Post up the name plate on your existing motor and we can help you more.

 

[DeeKay]

If you had read my post I wrote that unless he had 208V the motor would need to be replaced or buck/boost transformers would have to be used, but since the OP’ s photos show single phase panels, we have to assume no 3 phase so a 7.5 HP single phase motor would be the best choice in my opinion but the existing mag starter may not be able to handle a 7.5 HP single phase motor.

200V is the rated voltage for 208V, like 230V motors are used with a 240V supply, compressors are frequently supplied with a single voltage 200V motor when they are run on 208V rather than a 200-230/460V motor.

My bad, I did read it. Just hadn't had enough coffee yet, I misunderstood and thought you were saying you have to buck 208 down for a 200volt motor to run.

 

[GlennRobinson]

You will want to match frame size, most likely 213 or 215...maybe 184
Synchronous speed(RPM)
TEFC or ODP; doesn't really matter but ODP is generally cheaper.
.....

Post up the name plate on your existing motor and we can help you more.

As requested. Looks like the frame is 213T (whatever that means)

 

[Norcal]

Match the frame size, HP, & RPM, for a replacement single phase motor, and everything should match up, but do check the HP rating & coil voltage of the magnetic starter to see if it can support your replacement motor.

 

[GlennRobinson]

Found this one.

RPM isn't exact but the closest I found, so far.

Where would I find the magnetic starter information?

 

[DeeKay]

As requested. Looks like the frame is 213T (whatever that means)

Frame size is the NEMA frame size (or IEC for European stuff) Motor frames were standardized some time back in the 50s so that you don't have to buy an exact replacement from the same manufacturer, A Siemens 213T frame motor will have the same foot mounting dimensions, same shaft diameter, length etc as say a Baldor or Leeson 213T. That's not to say there aren't exceptions to the rule, but those will generally be called out on the nameplate or drawing as "NEMA non standard" and usually only apply to special motors, like severe duty stuff.

Like Norcal said, match Frame, HP and RPM.

RPM doesn't have to be exact, as long as it's close to 1800rpm (this is the synchronous speed or speed the motor would turn at in a perfect world.)

Your motor is ODP(open drip proof) but if you find a TEFC(totally enclosed fan cooled) that will work fine as well.

Continuous Duty is ideal.

Take a picture of the starter on your compressor

 

[wyliesdiesels]

post a pic of the label on the mag starter.

you will need to change the heaters or dial settings (for solid state) on the overload relay. you might also need to change the coil in the contactor, depending on the rated voltage

 

[GlennRobinson]

I am learning a lot from this thread.

Here is the control panel.

And a close up of the 2 main components.

 

[TRWham]

post a pic of the label on the mag starter.

you will need to change the heaters or dial settings (for solid state) on the overload relay. you might also need to change the coil in the contactor, depending on the rated voltage

Might even need to change the contactor itself. The 3 phase is likely to be 30 A but he'll need 40 or better to run a single phase 240 V 7.5 hp motor.

ETA: pictures posted as I was typing. Looks like contactor is okay.

 

[firebirdparts]

I don't know that an electrician will have ever seen a phase converter. He might have. Everybody is using inverters now that they're cheap.

 

[KenC]

That's mathematically impossible.
1.732 is the multiplier (square root of 3) that is used.
122 X 1.732 =211.304

Actually it is, as the voltage moves somewhat depending on time of day (system level loading) and the loads in use in my shop. And mine is a cheap meter.

I have seen the readings stated at one time or another but probably not at the same time.

For instance, Sunday I measured the hi leg at about 214, down from the early observation. About 124 on one leg, and 122 on other. Another day and time will yield slightly different.

Best part of my situation is that the utility installed the second transformer and 3rd conductor free! My old single phase panel fried the main breaker after only 50some years, I had a good used Sq D panel full of breakers and I wanted a 3ph compressor and table saw. Just asked at the electric dept shop and they provided me a new meter base which I installed and they installed the rest.

That would never happen in the current city administration.

 

[DeeKay]

Contactor looks ok, just have to find a heater table to figure out what to resize your overloads to.
Any part numbers on the overload? (The thing with the motor leads attached to it, under the contactor(which is the thing that says Furnas on it)