Need 5HP compressor motor and starter

[md21722]

I'm getting a 5HP air compressor that currently has a 3 phase motor. I need to replace it with a 1 phase 230V motor.

Because the compressor is located in the same general area where angle grinders are used, I am looking at getting a TEFC motor to keep the grinding dust out of the motor. Looking at the Baldor EL3612T or L3612TM:

http://www.ebay.com/itm/EL3612T-5-H...897477?hash=item58be2f5e85:g:qGsAAOSwNSxU08Qu

but for the price difference I can get a ODP motor and change it once and and break even!

http://www.ebay.com/itm/5-HP-Single...722591?hash=item4163971f5f:g:qCkAAOSwjVVVup4a

I was also looking at Eaton magnetic starters, something like this:

http://www.ebay.com/itm/EATON-MAGNE...068482?hash=item3f340ae382:g:h4cAAOxyQqBRHo10

I would prefer an ON/OFF switch but those seem to add $200 to the price!

Any comments or suggestions would be appreciated!

This will be used in a home shop, not a factory.

Thanks!

 

[Steevo]

I used this Baldor 5HP on my compressor and have been very happy with it.
http://williamsonneelectric.com/5hpbaldoraircompressorelectricmotorl1410t.aspx

 

[sld961]

I would prefer an ON/OFF switch but those seem to add $200 to the price!

Just get a pressure switch that has an on/off switch.

 

[Milton Shaw]

Pressure switches are usually good for 5 hp motors, above that you need to use magnetic starter. I would just use something like an a/c outside disconnect for the switch and then check to see the rating on the pressure switch that comes with the compressor and see if you need to upgrade it. Northern carries a couple of pressure switches one for single stage 125 pressure and one for two stage 175 pressure. Square D brand switches so they work about as good as any you can get. (Not listed in catalog that I could find just in stores for less than $50)

 

[sld961]

Pressure switches are usually good for 5 hp motors, above that you need to use magnetic starter. I would just use something like an a/c outside disconnect for the switch and then check to see the rating on the pressure switch that comes with the compressor and see if you need to upgrade it. Northern carries a couple of pressure switches one for single stage 125 pressure and one for two stage 175 pressure. Square D brand switches so they work about as good as any you can get. (Not listed in catalog that I could find just in stores for less than $50)

With a 5hp, I wouldn't use the pressure switch to switch the load, I would use it to switch the mag starter.

 

[manwithtools]

You could opt for a VFD if the current three phase motor is constructed appropriately for your grinding environment. Just be sure the VFD is rated for the environment or is inside of a dust proof enclosure. A VFD is likely cheaper than the replacement single phase motor and control package.

Be sure to get a VFD rated for the 5hp output use with single phase input. You might have to dig through the specs of the VFD - three phase input models can be used with single phase input but require de-rating. Wire it up using the existing pressure switch to control on/off.

 

[Norcal]

You could opt for a VFD if the current three phase motor is constructed appropriately for your grinding environment. Just be sure the VFD is rated for the environment or is inside of a dust proof enclosure. A VFD is likely cheaper than the replacement single phase motor and control package.

Be sure to get a VFD rated for the 5hp output use with single phase input. You might have to dig through the specs of the VFD - three phase input models can be used with single phase input but require de-rating. Wire it up using the existing pressure switch to control on/off.

After 3 HP, single phase input VFD's get REAL expensive in most cases a 10 HP drive has to be used, derating it 50%, this assumes the phase loss protection can be disabled.

 

[md21722]

After 3 HP, single phase input VFD's get REAL expensive in most cases a 10 HP drive has to be used, derating it 50%, this assumes the phase loss protection can be disabled.

What I was thinking. VFD's are great for low HP. I'm really just looking for motor & mag starter alternatives to the ones I've found. It looks like the Leeson TEFC are in the $400-500 range so I'll probably go that route unless I hear Baldor's are just that much better.

 

[manwithtools]

I'll wager you can buy a VFD that will work for $300 or so, 10hp three phase input, derated by .578 giving 5.78 HP output on single phase input. You might need to put it in an enclosure for another $100 - total cost is still less than a new single phase motor and control.

Most VFD's can be used with single phase in, phase loss detection can easily be disabled if it's part of the drive feature set to begin with - unless it's a really old VFD - in which case you don't want it anyway.

If you decide to change motors; be sure to get the same NEMA frame size so that mounting and shaft sizes,etc. are the same as the existing motor or you will have other issues to deal with.

 

[chrispyny]

I'm getting a 5HP air compressor that currently has a 3 phase motor. I need to replace it with a 1 phase 230V motor.

but for the price difference I can get a ODP motor and change it once and and break even!

http://www.ebay.com/itm/5-HP-Single...722591?hash=item4163971f5f:g:qCkAAOSwjVVVup4a

I was also looking at Eaton magnetic starters, something like this:

http://www.ebay.com/itm/EATON-MAGNE...068482?hash=item3f340ae382:g:h4cAAOxyQqBRHo10

I would prefer an ON/OFF switch but those seem to add $200 to the price!


Thanks!

That motor and mag starter are EXACTLY what i used when i purchased my very lightly used quincy qt-7.5 compressor at auction 2 years ago. I removed the 7.5hp 3ph baldor motor, replaced it with the l1430t you linked to and same mag starter you linked to (bought both mine from same vendors you linked to) and wired up a leviton n1303-ds 30amp switch inline and called it a day. Runs like a raped ape.

You can barely see the switch to the left of the pump, below the intake muffler.

http://www.electricsuppliesonline.com/leviton-n1303-ds.html

 

[wyliesdiesels]

Glad u didnt use an outlet and plug!

 

[chrispyny]

Glad u didnt use an outlet and plug!

Never planned too. That would be nuts.

I didn't need the switch as my subpanel is on the other side of the door, 3 feet from the compressor as can be seen here.

I didn't want to use a breaker as a switch, and if i leave the compressor on, it will cycle on once at night and wake me up as my bedroom is over the garage.

I strongly suggest you do not use a pressure switch for a 5hp motor. Get the mag starter you linked to like mine and be happy with a quality, safe install.

ALSO, you MAY have to change the pulley on the motor to a smaller pulley. You can not reuse the pulley off the 3 phase motor if you downsize like i did. It will be to big and place undue stress on the smaller 5hp motor. I think you said your current set up is 3 ph 5hp, so you may be ok.

I called Quincy directly in IL, and a tech did the math on the phone with me in 2 seconds, determined a nice smooth speed of 700 rpms for my pump (500 is min on a qt-7.5 pump), gave me part number for the pulley, and i ordered the pulley and some quincy oil for an oil change from my local quincy supplier 15 min from my house.

Also i have to add a overly hautz motor plate to my set up. When i put my new belt on, i tried to get it as tight as i could which worked well for the last 2 years. But with some use, the belt has stretched a touch, and i noticed that when the compressor kicks on, i hear a slght chirp upon start up. The belt is a tad loose and i have no patience to fight the motor on the compressor plate without an adjustable screw which comes on motor bases.
A nice OH base that fits our l1430t motors with 184T frames is $20 on ebay. I just haven't got off my **** and ordered one yet.
Do yourself a favor and buy one yourself.

For example...

http://www.amazon.com/dp/B00B9KP9TW/?tag=atomicindus08-20

 

[wyliesdiesels]

Never planned too. That would be nuts.

Yes it would be but unfortunately people do it all the time.

Standard NEMA outlets are rated to about 3HP....

 

[md21722]

I talked to Pacific Air Compressors out of Portland and they suggested the same Baldor motors Steevo suggested. They also suggested a Square D motor starter. They said they have had fewer problems with them. They also suggested using a pressure switch with an ON/OFF switch.

I got the compressor going with a Square D motor starter & pressure switch and went with a WEG motor for now.

I do have a question about the WEG motor. Most motors I've seen have plain wire leads. The WEG had crimped on ends as if it was going to be connected to a terminal bar. Why did they do that? They also put the wire lead labels real close to these crimped on ends so if you cut the crimped ends off you'd probably want to relabel the leads.

I am also wondering what the "best" flexible conduit to use is? There is aluminum, steel, and plastic type. The compressor will not be used outside, but it will be used in a dusty environment. I am thinking the aluminum will be fine.

 

[matt_i]

Those crimp lugs on stranded wire are to keep strands from wandering and or getting smashed out of a larger diameter screw terminal. More or less its an "edge band" which keeps the full cross section of the wire in better conduction. Definitely something that's made its way over from Europe, like the screwless terminal strip connections they love to put in machinery.

I would go with some kind of metallic liquid tight. I've used the plastic-only type and it was sketchy because it was molded with a "lay" that would not sit flat or straight no matter what I did and it looked like a coiled snake unless I clamped it down every 8".

Also, if you get a NEMA -rated starter, even good used, it will outlast you in my opinion. NEMA is built to a standard that's 10x that of an IEC rated starter. Just look at the physical size of the components....Sq D, Allen Bradley, Siemens, Furnas will all work quite well.

 

[manwithtools]

matt_i is referring to a ferrule, a metal sleeve that is crimped around the stripped wire strands as he describes. I'm curious about your WEG motors leads, are they ferrules or ring terminals crimped on the wires?

Ferrule:

Ring terminal:

If they are ring terminals; its because on most of the WEG motor line they will have stud terminals inside the motor junction box to allow convenient connection to the proper winding's depending on voltage.

If they are ferrules, the Wago connectors work nice with them.

If they are ring terminals, you can put ring terminals on your supply conductors and then bolt them together and tape over the bolted connection with insulated tape and electrical tape.

 

[md21722]

They used ring terminals. There was no terminal or stud block. Just a bag of screws and nuts.

 

[manwithtools]

Then the intention is to use the screws and nuts to connect to the supply conductors. Ring terminals on the supply, screws and nuts through the ring terminals, wrap each connection with PVC tape, then a layer of rubber tape and then PVC tape again on the outside.

 

[justsam]

As much as I am a fan of the Wago's, I am not sure I would use them where there will be high in-rush current. Their nominal rating is 32 Amps, but I have not seen any form of surge/duration rating for them. Also I believe the maximum wire gauge is 12ga.

Sounds like it is moot since the motor has ring terminals.

 

[manwithtools]

Yep, good point about the Wago's. I'm used to using them on smaller motors; 5 HP and less and generally 480 VAC so lower amperage. Thanks for pointing that out.