wiring air compressor

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Old 07-12-04, 05:35 PM
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wiring air compressor

I just came into an old Kellogg air compressor with a 220v 16 amp 1 phase 3hp motor. It came wired to a Cutler Hammer box that I believe is a starter. Just what does a starter do and do I really need it? I have a friend with a similar compressor and he doesn't have a starter on his. I've looked around and noticed that starters are optional on a lot of big compressors.
I'm guessing that it ramps the motor rpms up slowly so it doesn't strain the compressor head.
The only concern I have is that the compressor was wired to a 60a circuit and I only have 100a in my shop.
I'm guessing that the extra amperage has something to do with the starter.
Thanks
 
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Old 07-12-04, 08:56 PM
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Okay, I'll add my humble opinion here, I'm sure a professional will chime in as well.... If your newly acquired air compressor has a 3 phase motor, and someone has set it up to operate on normal household 220 current, your "starter box" is probably a phase converter. If it isn't, you won't be able to operate the motor unless you have 3-phase power available (not likely unless your home is in an old factory). You need to verify this before you attempt to wire it in, or you'll be replacing the motor (or worse!).
 
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Old 07-12-04, 09:29 PM
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hoffman,

It likely is a starter.

A starter is used when the amperage of the motor exceeds the rating of the pressure switch.
It is a deluxe feature and would be a shame to remove it if there is nothing wrong with it.
It also would allow you to install a remote switch in the control circuit.

Take a look inside and tell us what you see.
 
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Old 07-13-04, 08:53 AM
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The starter is equipped with "heavy-duty" contacts that are specificly designed for conducting the heavy motor "starting-surge," and are far more durable than contacts on any other type of means for switching power to the motor.

The starter is equipped with "over-load" devices that will "sense" an excessive current that will over-heat and ruin the motor-windings.This prevents motor "burn-out".

The control-circuit of the starter is a low-current circuit that can be wired to a control-device such as a pressure-switch that automaticaly regulates the air-pressure.
 
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Old 07-13-04, 06:48 PM
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Attempting to expand my knowledge here... how does a starter differ from a relay? From PATBAA's comments, I assume the starter contains the relay switching, but also includes over- current protection. Is there more involved as well?
 
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Old 07-13-04, 07:21 PM
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A motor starter generally has a relay and an overcurrent device.
But, you can also get a manual switch with overcurrent protection and it will also be referred to as a starter.

In my trade circles a high current relay without overcurrent protection is referred to as a contactor.

You would recognize overcurrent protection by the presence of a reset of some type.
 
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Old 07-13-04, 09:36 PM
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Thanks for the input guys. I'll retain the starter and see if I can wire up a remote switch and a pilot lamp. I got lucky because it's an old commercial compressor with an 80 gal tank and parts are still available. I got it for cutting down a tree and hauling it off. A comparable compressor would cost a few grand
today
I was planning on using the motor from it on my Porter Cable compressor but the local compressor service store said the old Kellog American is a keeper and said my Home Depot compressor is a "toy" by comparison. I thought my 7hp 60 gal was pretty good but the electric motor crapped out after 3 years of medium duty. This new/old one has a big Baldor that weighs about a hundred lbs.
The motor is a 16 amp at 220 v and I'm thinking about putting it on a 30 amp circuit. It was originally on a 60 amp breaker but that seems a little overkill unless it had something to do with the starter.
What do you guys think?
Oh yea Greg, I found the front of the "starter" box and it does have a big reset button.
Here is a link to a description of a box with a similar number:
http://www.plccenter.com/Detail_New2...=CUTLER+HAMMER
It says "3 ph" But I know my motor is a single phase
 
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Old 07-13-04, 10:06 PM
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hoffman,

With any luck when you remove the cover of the starter there will be a sticker with a heater selection chart.
There is a good possibility if the motor was originally 3 phase and converted to single phase the heaters may not match the new motor.

If the chart is there you would take the running amps of the motor on the nameplate and match a heater to that amperage.

If someone didn't know about this the heaters may have been bypassed because a single phase motor draws more amps than 3 phase and would repeatedly trip the starter.
 
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