Air Comp - magnetic starter or not?

[slackdaddy1]

Looking at new compressors, vs rebuilding my old (and new motor)
The Champion 5hp model says "No mag starter needed"
http://www.tptools.com/Champion-5HP-2-Stage-80-Gal-Air-Compressor,6248.html
What makes one 5hp (22 amp) motor need a magnetic starter, and anoth not ??

Thanks,
Slack

 

[slodat]

If you are switching power to a true 5hp motor with a pressure switch, it will be hard on the contacts. I had this setup. Ultimately the pressure switch contacts welded shut and the compressor ran continuously, popping the pressure relief valve until I went out in the shop and shut it off.

A magnetic starter uses a small control signal to energize the coil. This low current is no problem for the pressure switch contacts. It’s required for anything over 5hp as far as I can see. I’ve never seen a pressure switch rated for 7.5hp and up.

I recommend the magnetic starter with correctly sized overloads.

 

[driftpin]

Aren't magnetic starter switches used to be able to disconnect the power from a cutting appliance so that if the power is interrupted the appliance is turned off and that restoring power to the appliance does not result in the cutting appliance starting again.

 

[454ragtop]

Aren't magnetic starter switches used to be able to disconnect the power from a cutting appliance so that if the power is interrupted the appliance is turned off and that restoring power to the appliance does not result in the cutting appliance starting again.

Not the case on a compressor, if the pressure switch is calling for it, it will restart when the power comes back on. It does work that way on machine tools controlled by 2 momentary push button switches.

A mag starter is definitely the way to go on a compressor with a true 5 HP motor.

 

[The Tool Tyrant]

Magnetic Starter MAY not be required, but 'Repeated Replacement Of Pressure Switch' WILL be!

 

[md21722]

Magnetic Starter MAY not be required, but 'Repeated Replacement Of Pressure Switch' WILL be!

Correct.

 

[md21722]

About 2 years ago I was quoted $2,650 or so from my local compressor dealer for a Champion R-series with a TEFC motor & a standard magnetic starter. The prices have probably gone up a bit since then but you might want to look local first.

The R-series is one step above the Centurion series. There's nothing wrong with the Centurion series, but the R-series pumps have an integrated cylinder and head design so there's no possibility for a head gasket to blow. There's no valve plate. The valves are under the manifolds and use aluminum and copper washers.

The TEFC motor was a $100 add-on to the base price. TEFC motors are great in dusty and dirty environments because don't blow air through the motor windings like a regular ODP motor.

And, as mentioned, the magnetic starter keeps the load off the pressure switch.

 

[slackdaddy1]

Okay,, Mag starter it is.
I have a 80gal IR T30 Horz tank, and a Champion R15 pump, That appears "OK" but will rebuild if using.
By the time I rebuild the R15, buy a 5hp 1750 motor and all the do-dads,, I will have about 1000.00 in it (If there is nothing major wrong in the pump)
I can buy a big box store 2 stage brand new for 800.00,,, hard decisions for a home hobbyist

 

[slodat]

That R15 is a great pump. Much better than the big box junk.