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Old 12-09-2009, 01:19 AM   #16
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Older air compressor wiring help


Yes, it does.

18 amps is slightly high for a 3 HP, but it's way low for a 5. I'm betting on the 3.

Whatever starter you get, use overloads for 18 amps.

This also helps on the starter as well. A NEMA size 1 will operate a 3 HP single phase motor, two pole or 3 pole.

A 23 amp IEC starter is good for 3 HP, as is a 25 amp Definite Purpose starter. A size or two larger will last longer.

Rob

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Old 12-09-2009, 05:03 PM   #17
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Sorry but I need a little help understanding. Two poles means? If I buy the whole box with the starter will it come with a wiring diagram?
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Old 12-09-2009, 05:16 PM   #18
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twp poles equates to two sets of contacts so you can basically open or close two separate wires.

and yes, a motor starter does come with wiring diagram in the thing but it does not figure in a pressure switch or oil level switch (if used). those will have to be added to the circuit in the control circuit.
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Old 12-09-2009, 05:45 PM   #19
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So I just talked to local repair tech and he suggested just wiring it through the pressure switch and using that as the starter while he looks to see what he has for starters. Any thoughts on that?
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Old 12-09-2009, 05:53 PM   #20
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Just looked in on this thread and I noticed that this furnas contactor as said needs replacing but I'm wondering with so many parts missing the contacts cover is off or missing, the coil is missing and the cover is off or gone. I think on the cover there may have been a momentary start button or rocker toggle? Just mentioning as that may need to be addressed in the new wiring.


Also e bay sometimes has some very good deals on this type of motor starter.
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Old 12-09-2009, 05:54 PM   #21
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it will work for now but the contacts on a pressure switch are often not rated for the current draw of a motor. That is exactly why you use a starter; so you control the motor power wiring with a control circuit that either has a lower voltage or has a lower current flow.

anyway, what will happen is the contacts could weld closed and you may not notice until the pop off valve opens or they could burn bad enough not not start the motor.
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Old 12-09-2009, 07:12 PM   #22
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Quote:
Originally Posted by Stubbie View Post
Just looked in on this thread and I noticed that this furnas contactor as said needs replacing but I'm wondering with so many parts missing the contacts cover is off or missing, the coil is missing and the cover is off or gone. I think on the cover there may have been a momentary start button or rocker toggle? Just mentioning as that may need to be addressed in the new wiring.


Also e bay sometimes has some very good deals on this type of motor starter.
actually there could have been stop start buttons which does need to be present to make all of this work.

good catch.


lash, if there are no momentary buttons elsewhere, you need to incorporate start button and a stop buttons. They should be momentary. The start is a normally open contact and the stop is a normally closed contact.


micromind; why didn't you remind me when I asked you?

great job with the explanation and info by the way.
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Old 12-09-2009, 08:37 PM   #23
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Thanks guys. I will make sure of that when I decide on the new starter. The cover is indeed missing so I will replace the box as well. I bought this from a guy who inherited it from his dad. He initially wanted $125 but by the time I met him the next morning he wanted $250 because he said he have an offer for that much on the phone. What do you think did I over pay?

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Old 12-10-2009, 12:41 AM   #24
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Older air compressor wiring help


Sorry, nap. I guess I was too busy with the techno-babble. lol.

Baldor is one of the very top motor manufacturers.

The pump looks like a Champion. They seem to last forever as well.

I know it's sort of old, but back then compressors were built to last. I think you got a pretty good deal. A similar compressor goes for around $1500 new.

Rob

P.S. I don't think the pressure switch alone will handle a 3 HP motor. At least not for very long. Most of them are rated for 2 HP at 240 volts. It'd be a good idea to include the low oil switch in the circuit as well. It won't handle any HP, just control of a starter.
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Old 12-10-2009, 01:29 AM   #25
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Quote:
Originally Posted by nap View Post
actually there could have been stop start buttons which does need to be present to make all of this work.

good catch.


lash, if there are no momentary buttons elsewhere, you need to incorporate start button and a stop buttons. They should be momentary. The start is a normally open contact and the stop is a normally closed contact.


micromind; why didn't you remind me when I asked you?

great job with the explanation and info by the way.
Yeah... I'm not going to try to compete with micro on his technical knowledge.

Yes I meant to say start/stop buttons but heck who wants to turn this baby off ???? I think.. though I am not positive... that furnas used a black rocker type momentary switch to operate the starter . There is a chance you might find a picture of the starter on a surplus electrical site or may be has one up for sale. Might check and see would make the change over a tad easier but not much. I'm not so sure if push come to shove you could fuse the motor for overload and use a definite purpose contactor to start it in conjuction with the pressure switch. But that's the kansas farmer in me....

Is that an oil level switch on the compressor ?
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Old 12-10-2009, 10:25 AM   #26
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Quote:
Originally Posted by Stubbie View Post
Yeah... I'm not going to try to compete with micro on his technical knowledge.

Yes I meant to say start/stop buttons but heck who wants to turn this baby off ???? I think.. though I am not positive... that furnas used a black rocker type momentary switch to operate the starter . There is a chance you might find a picture of the starter on a surplus electrical site or may be has one up for sale. Might check and see would make the change over a tad easier but not much. I'm not so sure if push come to shove you could fuse the motor for overload and use a definite purpose contactor to start it in conjuction with the pressure switch. But that's the kansas farmer in me....

Is that an oil level switch on the compressor ?
ya mean like this?



Unless he runs across somebody with some old parts, I don't think he is going to get the rest of this starter. I think his best bet would be just replace with new.

and the switch to the near right of center of the compressor; it looks like a micro-switch (actuator pointed to to the left.) I do not know what that would be for.

MM, any ideas?


lash; to the value of the compressor:

I don't think you are going to like the cost of a new starter but at $125, if that thing works, you got a steal. I think at $250 you still did good..

I cannot tell but is it single or dual cyl and is it single or dual stage? There are a lot of pipes running around. . Peerless' newer 2 stage compressors put the cylinders in a V configuration. I don't know if they did side by side configuration with their older compressors so that is why I ask.

any tags that give a CFM or LPM rating on the thing?
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Old 12-10-2009, 11:40 AM   #27
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Older air compressor wiring help


I'm pretty sure that micro switch is for oil level shutdown. If the oil level gets too low the rod that holds the switch closed moves so far down that the actuator stem frees and opens the latching circuit.

Was that furnas starter for sale and was it rated properly?

I would have gave 250 for this compressor but I have all the stuff to get it back going again. A new starter with enclosure box is not the cheapest thing and your going to have anther 150 in it at best...unless you find something surplus but your going to have to know what you are looking for.

Right now if there is a bottom drain I would open it and get the water out of the tank might be a bunch in there.
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Old 12-10-2009, 08:59 PM   #28
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That's almost certainly a two stage pump. It looks a lot like a Champion, but it's hard to tell.

There are two cylinders, a larger one and a smaller one. On this pump, they're in-line, others are V. The larger cylinder is the first stage, it draws air in through the filter, and compresses it to about 40 PSI or so.

The air exits this cylinder and goes into the finned tubing. This is the intercooler. It if then fed into the smaller cylinder, and exits into the tank. The smaller cylinder is closest to the flywheel, because it runs hotter.

The maximum pressure on this pump is 175 PSI. It'll very likely produce around 10 CFM at 175 PSI. Use straight 30 weight oil in it, not 10-40 or any multi-weight. 'Air Compressor Oil' is almost always 30 Wt, and will work fine. Be careful if you use synthetic oil. It doesn't get along with mineral oil very well, and the crankcase will need to be flushed out first. It also will eat away at polycarbonate (the plastic used on filters and such).

The micro-switch looks a lot like a low-oil shutdown. Just wire it in series with the pressure switch. It'd be a good idea to test it first, they're notorious for failing. With the crankcase full of oil, the contacts should be closed (have continuity).

Rob

P.S. Ebay is your friend when looking for a starter. They're unbelievably expensive new.
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Old 12-10-2009, 11:36 PM   #29
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http://cgi.ebay.com/Square-D-starter...item20ae6e766d

Can't read the labels on this but could it be about what I am looking for? I need to contact them for more detail if you think I am on the right track. The switch in question is indeed a low oil cutoff. There is a cork float behind the sight glass that floats the copper rod up and closes the contact. I think the copper button on the side is supposed to be a reset but it is frozen I just took the cover off and cleared the lever by hand until the rod floated up. By the way I have it wired directly to the motor at the moment and everything seem to work. I had to fix what I believe is called the "unloader" valve. It is located on the front of the pump and uses a ball bearing between a spring and a copper rod. It was leaking all of the air out and would not shut off as it is supposed to do. I took it apart and oiled it with compressor oil and now it just lets a small amount of air out and then shuts off. I believe it is supposed to make it easier for the pump to start by dumping air pressure in the pump. I can't find any numbers on the pump. It is a dual stage. By the way it is the quietest compressor I have ever been around. It makes about 1/10th of the sound of my oilless compressor. Label inside pressure switch say 145 cut in and 175 shutoff pressures. By the way what kind of grease should go in the motor if those are grease serts? Tank has been drained. About a pint of water.



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Old 12-11-2009, 12:16 AM   #30
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The starter you're looking at might work, I can't tell what the coil voltage is, but 240 would be best. Since there's a white wire in it going to the overload block, I suspect it's 120. If so, you'll need to either run a neutral along with the power circuit, get a 240 coil, or install a control power transformer.

The hand-off-auto switch in not needed, but it can be easily removed, or left on and used as a control switch.

Square D is a good brand, so is Allen Bradley. The overload heaters for Square D are likely easier to get than the Allen Bradley. The square D heater will be a B28.0, the Allen Bradley will be a W59. A two pole starter for single phase motors uses one heater, a 3 pole uses 3 heaters even it the motor is single phase. They cost about $15 each.

Rob

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