There are some models of 5hp air compressors that do not require a magnetic starter. The models that do require the starters are a few hundred more. Is the added cost of the different motor and starter worth the added cost? My guess is it has something to do with the longevity of those parts. The brands I have looked at so far are Quincy, Champion, and Curtis.
Real 5hp air compressors
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I'd think of the magnetic starter as you would the starter solenoid in a vehicle. You're signaling the magnetic starter to pull in, which turns the motor on, exposing the magnetic starter to the 30+ amp current draw upon startup instead of whatever you're using to turn the compressor on (pressure switch, hand switch, timer, etc.)
is this for home use? are you running a body shop on the side?
JHZR2
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Do you mean a soft starter to minimize inrush current on the motor start?
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
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My 5HP two stage does fine without a magnetic starter. The magnetic starters do more than a starter solenoid, as they protect against overload (I believe) and most important they do not start the motor after a power failure. The magnetic starter is an expensive option. I think my motor has a thermal breaker you push in to reset.
Originally Posted By: user52165
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Very educational. At first I thought the O.P was talking about capacitor start motors (which ARE available on single phase, as shown in the Ingorsol Rand links).
My workplace compressor has the thermal load protector described by Donald.
Can anyone explain the benefits or necessity to have a magnetic starter in some situations? Donald explained overload protection/safety functions. Are there other benefits that improve compressor operation (cost/value/efficiency?).
Thanks.
My workplace compressor has the thermal load protector described by Donald.
Can anyone explain the benefits or necessity to have a magnetic starter in some situations? Donald explained overload protection/safety functions. Are there other benefits that improve compressor operation (cost/value/efficiency?).
Thanks.
Originally Posted By: dave123
Originally Posted By: user52165
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Not needed. I don't want to hijack this thread any more. I will be glad to start another thread on this subject if you need it.
FWIW - I use a real 3 HP compressor motor @ 240V and have done extensive sandblasting. The key is honest HP. Not "peak", "developed", etc or the other misleading terms so often used now.
Originally Posted By: user52165
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Not needed. I don't want to hijack this thread any more. I will be glad to start another thread on this subject if you need it.
FWIW - I use a real 3 HP compressor motor @ 240V and have done extensive sandblasting. The key is honest HP. Not "peak", "developed", etc or the other misleading terms so often used now.
I run a now 17 year old Campbell Hausfeld castiron twin,5hp. Run on 110 or 220 capaciter start. I believe it to be a "real" 5hp-not made anymore but a lot around at garage sales etc.
Seems pretty much indestructable.Replaced pressure switch once and change oil yearly.
Oh-just remembered I bought mine at Sears-they carried them a long time-there's alot of them around.Some I have seen appeared to have had little use.
Seems pretty much indestructable.Replaced pressure switch once and change oil yearly.
Oh-just remembered I bought mine at Sears-they carried them a long time-there's alot of them around.Some I have seen appeared to have had little use.
Originally Posted By: user52165
Originally Posted By: dave123
Originally Posted By: user52165
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Not needed. I don't want to hijack this thread any more. I will be glad to start another thread on this subject if you need it.
FWIW - I use a real 3 HP compressor motor @ 240V and have done extensive sandblasting. The key is honest HP. Not "peak", "developed", etc or the other misleading terms so often used now.
I am talking about a 7.5HP 25CFM @ 175 PSI pump not a 3HP tire filler
Originally Posted By: dave123
Originally Posted By: user52165
Originally Posted By: dave123
Sandblaster I would look at 7.5HP min
If he gets an honest 5 HP unit like this, it will handle any home job:
http://www.factoryauthorizedoutlet.com/ir/products/2340L5.asp?rt=2
There are so many phoney ratings out there, it is sad.
Like I said 7.5HP min for sandblasting.
Not needed. I don't want to hijack this thread any more. I will be glad to start another thread on this subject if you need it.
FWIW - I use a real 3 HP compressor motor @ 240V and have done extensive sandblasting. The key is honest HP. Not "peak", "developed", etc or the other misleading terms so often used now.
I am talking about a 7.5HP 25CFM @ 175 PSI pump not a 3HP tire filler
Originally Posted By: doitmyself
Very educational. At first I thought the O.P was talking about capacitor start motors (which ARE available on single phase, as shown in the Ingorsol Rand links).
My workplace compressor has the thermal load protector described by Donald.
Can anyone explain the benefits or necessity to have a magnetic starter in some situations? Donald explained overload protection/safety functions. Are there other benefits that improve compressor operation (cost/value/efficiency?).
Thanks.
You can also wire a remote on/off box with small gauge wire to turn it on or off as the wire only carries the load of the relay.
I would guess that OSHA requires magnetic starters on a lot of equipment so someone does not get into a dangerous situation with the power off and then have the power come back on and the machine start up. The lockouts usually go on the magnetic starter.
Forget about HP, use CFM and PSI. And a two stage will produce higher pressure than a single stage. And cost more and typically be a better compressor. Don't confuse cylinders with stages. If its not a real business environment, someone might get away with adding an extra tank to a smaller compressor.
Very educational. At first I thought the O.P was talking about capacitor start motors (which ARE available on single phase, as shown in the Ingorsol Rand links).
My workplace compressor has the thermal load protector described by Donald.
Can anyone explain the benefits or necessity to have a magnetic starter in some situations? Donald explained overload protection/safety functions. Are there other benefits that improve compressor operation (cost/value/efficiency?).
Thanks.
You can also wire a remote on/off box with small gauge wire to turn it on or off as the wire only carries the load of the relay.
I would guess that OSHA requires magnetic starters on a lot of equipment so someone does not get into a dangerous situation with the power off and then have the power come back on and the machine start up. The lockouts usually go on the magnetic starter.
Forget about HP, use CFM and PSI. And a two stage will produce higher pressure than a single stage. And cost more and typically be a better compressor. Don't confuse cylinders with stages. If its not a real business environment, someone might get away with adding an extra tank to a smaller compressor.
5 HP is right at the limit where a mag starter is needed. It uses a lower amperage on the pressure switch (like a relay) to start the motor. It will increase the life of the pressure switch, and if the motor does not have thermal protection, the heaters in the mag starter will do that for you.
Some 5 HP compressers can keep up with a blast cabinet as they will produce almost 20 SCFM at 175 psi (units like the Quincy 325 that I have and similar models from other companies).
Some 5 HP compressers can keep up with a blast cabinet as they will produce almost 20 SCFM at 175 psi (units like the Quincy 325 that I have and similar models from other companies).
Originally Posted By: GeorgiaHybrid
5 HP is right at the limit where a mag starter is needed. It uses a lower amperage on the pressure switch (like a relay) to start the motor. It will increase the life of the pressure switch, and if the motor does not have thermal protection, the heaters in the mag starter will do that for you.
Some 5 HP compressers can keep up with a blast cabinet as they will produce almost 20 SCFM at 175 psi (units like the Quincy 325 that I have and similar models from other companies).
I was thinking about a mag starter and a pressure switch. I wonder if they have 2 relays in them. I assume if you loose power and then regain power, the motor will not come on from the pressure switch, you would have to press the start button first.
Years ago I worked in a roof truss factory while going to college and every machine on the floor had a mag starter. The largest was a 50 HP electric motor powering a hydraulic pump. No way would you want any of those machines coming back on after a power failure by themselves.
5 HP is right at the limit where a mag starter is needed. It uses a lower amperage on the pressure switch (like a relay) to start the motor. It will increase the life of the pressure switch, and if the motor does not have thermal protection, the heaters in the mag starter will do that for you.
Some 5 HP compressers can keep up with a blast cabinet as they will produce almost 20 SCFM at 175 psi (units like the Quincy 325 that I have and similar models from other companies).
I was thinking about a mag starter and a pressure switch. I wonder if they have 2 relays in them. I assume if you loose power and then regain power, the motor will not come on from the pressure switch, you would have to press the start button first.
Years ago I worked in a roof truss factory while going to college and every machine on the floor had a mag starter. The largest was a 50 HP electric motor powering a hydraulic pump. No way would you want any of those machines coming back on after a power failure by themselves.
Originally Posted By: Donald
No way would you want any of those machines coming back on after a power failure by themselves.
That's the difference in the motor control world in what's referred to as "2 wire" and "3 wire" control ... an on-off switch vs start and stop push buttons.
There are DEFINITELY places where you want a large motor to come back on ... and others where you want to require operator intervention on a small motor.
USUALLY those that come back on have some kind of protection so it won't do it 3 or 4 times quickly ... starting a large motor is hard on it. But there are situations where oversized fuses and little or no motor protection is normal ... fire protection pumps come to mind.
No way would you want any of those machines coming back on after a power failure by themselves.
That's the difference in the motor control world in what's referred to as "2 wire" and "3 wire" control ... an on-off switch vs start and stop push buttons.
There are DEFINITELY places where you want a large motor to come back on ... and others where you want to require operator intervention on a small motor.
USUALLY those that come back on have some kind of protection so it won't do it 3 or 4 times quickly ... starting a large motor is hard on it. But there are situations where oversized fuses and little or no motor protection is normal ... fire protection pumps come to mind.
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