Do I need a magnetic motor starter?

[Cinnabar325is]

Okay, here's the scenario: I'm rebuilding an old 80 gallon vertical Saylor-Beall compressor, that was refitted with with an IR T30 Model 242 pump before it came into my possession. It came to me in pieces and missing some parts.

It also has a relatively new Leeson 5hp, single phase, 21 amp motor.

I'm using an Allen Bradley Bulletin 836 pressure switch, exactly like this: http://www.ebay.com/itm/360628195577?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

So my question is, do I need to purchase a magnetic motor starter? The compressor did not come with one. It is my understanding that it may work without one, but it will burn up the contacts on the pressure switch rather quickly.

I was considering this model: http://www.amazon.com/dp/B0080HCUTE/?tag=atomicindus08-20

Thanks for your help!

Ryan

 

[pattenp]

It's good to have one, but I wouldn't spend that much on a starter though.

 

[Cinnabar325is]

It's good to have one, but I wouldn't spend that much on a starter though.

That's the cheapest one I've found by a LONG shot, discounting the Chinese ones on eBay. I want good quality.

The Square D units start at $325 or so and go up from there.

 

[Trey T]

IF your switch can handle the running and start load, you don't need a magnetic starter. I don;t know the specs of the switch you bought to tell you the answer you want to hear.

If I have to guess, yes.

 

[pattenp]

Here's the same starter for less.

http://www.ebay.com/itm/NEW-GE-Magn...A%2BFICS%2BUFI&otn=21&pmod=271069040982&ps=54

 

[Cinnabar325is]

Here's the same starter for less.

http://www.ebay.com/itm/NEW-GE-Magn...A%2BFICS%2BUFI&otn=21&pmod=271069040982&ps=54

Wow, thanks!

 

[zkling]

Yes you will. Look under the control circuit ratings towards the bottom of the page. You should be able to find a motor start for pretty cheap. Used of course.

http://www.ab.com/en/epub/catalogs/12768/229240/2286210/9861080/9861082/Technical-Data.html

 

[Todd.Brock]

The way, I have come to understand magnetic starters on a 5 hp motor, which seems to be the threshold for needing one is this.. If the motor is thermally protected, then a mag starter is not required. I have been looking at compressors, where a 5 hp 1725 Baldor motor is standard along with a mag. starter. A value line compressor will still have a Baldor , but maybe a 3450 rpm, thermally protected unit ( has a reset button). I learned this with FS Curtis.

I replaced the 22-23 amp pressure switch on my Champion 5hp with a Sunny ( Chinese ) from surplus center. It works great. I also had one on my old 5 hp 80 gallon IR. Both motors are thermally protected. I could not find a replacement from Furnas that matched amps and 140-175 psi cuts.

 

[zkling]

Another and possibly better option is to do what Todd did and just buy a cheap, higher current rated pressure switch. The switch you bought is a pretty application specific switch designed for low amp circuit control. You could the one you bought, but you will need a motor starter to go with it, which would be overkill really, but the "best" in overall setup.

 

[cyato]

Definitely spend the money on the mag motor starter. Especially at that price. I burnt up a couple expensive motors trying to get by without one.

 

[66dave]

The mag starter is simply an electromagnetic contactor, used in place of a mechanical pull type.

One of the primary purposes of a mag starter is for safety. You see these on a lot of equipment because if the power fails while using the tool and stops it these is no way it can restart unless you push the start button again. If you did not have it there is a chance that you could be injured when the power comes back. Imagine if you we're using a lathe or a large table saw...yikes!

 

[Trey T]

almost right but it's a contator with thermal load protector.

If a motor has thermal load protector (reset button), get a contactor w/ box for switching, much cheaper.

The mag starter is simply an electromagnetic contactor, used in place of a mechanical pull type.

....

 

[bronc3buster842001]

Here's the same starter for less.

http://www.ebay.com/itm/NEW-GE-Magn...A%2BFICS%2BUFI&otn=21&pmod=271069040982&ps=54

i ordered mine from here and was sent a Square D one as a replacement... Said he was having problems with the Ge ones...

 

[Cinnabar325is]

i ordered mine from here and was sent a Square D one as a replacement... Said he was having problems with the Ge ones...

I guess we'll see, I bought the GE one last night and it shipped today.

 

[Todd.Brock]

Did I get called cheap ??? . My 5hp champion does not have a mag starter. Those switches I referenced are about 20 bucks. I agree a mag starter would be ideal though.

 

[Zrexxer]

That seller on both Amazon and eBay - UPE Group - is a top notch outfit to do business with. I bought my Square D mag starter from them, and they patiently answered all my questions and explained how to choose the overloads.

I will turn to them first if I need to buy a mag starter again.

 

[PT Doc]

Definitely spend the money on the mag motor starter. Especially at that price. I burnt up a couple expensive motors trying to get by without one.

what type of compressor did you have? motor hp? did the pressure switch have overload protection? Thanks good the info. it could be helpful for some folks.

 

[scw1991]

I've purchased several Square D type 8911 definite purpose mag motor starters with thermal overload protection from UDP. They are brand new. I've also purchased the Siemens mag starter with thermal overload protection as well. Not quite as heavy duty in construction but good enough and does the job just fine.

Forget trying to find a pressure switch that can handle a 5HP motor as it draws too much current. You can purchase a pressure switch rated up to about 3HP maximum.

 

[OccupantRJ]

Do you have an industrial salvage yard near you? If so, one can normally find all the heavy duty goodies at a very reasonable price off of salvaged equipment. Sometimes the parts are new, acquired when some facility closed shop. Besides, roaming the yard is an entertainment in and of itself. I have a 3/8" capacity plasma cutter from one that cost me a whopping $20. New forks for the forklift were $100 a pair. 40 foot semi trailer for $700. You get the idea. Lot of stuff shows up in these places because of manufacturing going offshore, and I'm there to find it.