electric motor question

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krautschmidt
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electric motor question

Post by krautschmidt » Thu Sep 29, 2005 6:27 pm

I inherited a wood jointer from my dad. It is a six incher and was wired for 220. I don't have 220 in the garage, so I changed it to 110. It runs for maybe 1 minute, slows down rapidly and then stalls out completely. I wait for a few seconds and then turn it back on. It does not trip the 20 amp breaker. The motor is a Westinghouse motor my dad put on. It is rated at 3/4 horse. Any ideas?

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Chris Smith
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Re: electric motor question

Post by Chris Smith » Thu Sep 29, 2005 6:40 pm

All houses in America bar a few, do have the 220 / 240 volts. <p>The two legs coming into your house are 120 and 120, making up the 240 that you can use for the motor. <p>Your motor sounds like it could be over heating and breaking down? <p>The windings may be shorting and losing their pull, or the bearings may be overheating, but its hard to tell by description alone? <p>But, remember you do have 220/240, so perhaps go back to what is needed?

Michael J
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Re: electric motor question

Post by Michael J » Thu Sep 29, 2005 8:18 pm

Does the motor have Run and Start windings.<p>You may be running on just the start windings.

Robert Reed
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Re: electric motor question

Post by Robert Reed » Thu Sep 29, 2005 9:06 pm

Kraut--<p>Need more info such as:
Induction motor or universal wound (brush type)?
Does this happen under load or no load ?
Does motor attain full speed (can determine by sound)?
Is motor excessively hot after shutdown (most motors equipped with thermal breakers internally and will auto reset when cooled) ?
Is there any unusual sound when motor is running ?

gerty
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Re: electric motor question

Post by gerty » Thu Sep 29, 2005 9:40 pm

Could also be a low voltage condition. Do the lights in the garage go dim when the joiner is running? If you can get to it safely, put a voltmeter across the motor terminals and start it and see what the voltage is.

Dean Huster
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Re: electric motor question

Post by Dean Huster » Fri Sep 30, 2005 5:27 am

A jointer is one of three shop tools that require a high-speed (3450 rpm) motor: table saw, jointer and shaper. A lot of folks make the mistake of using a low-speed motor motor with a large pulley to drive the jointer knives with a small pulley. You get the speed but lose all of the torque you need to run the tool, overheating the motor. Check for the motor speed.<p>A 6" jointer requires a MINIMUM of 1/2 horsepower and really needs a full horse to run at full capacity for any extended period of time. So the motor power doesn't seem too bad.<p>Make sure that the house wasn't poorly wired with #14. If it is using #12, check all the connections from the breaker out to the receptacle and make sure they're tight. <p>Are you sure you rewired the motor properly for the lower voltage? Double-check that.<p>Chris, although he may have 240 available on the property, it may be a royal pain in the katoosh to get it in to the garage, especially if it's a detached garage. In every house I've had, running 240v to the garage would have been a major undertaking since the garage was always on the opposite end of the house from the service panel. That's why I've always vowed that I'd have separate service to my shop when I build it. I'm still vowing. Dang, I need that shop.<p>Dean
Dean Huster, Electronics Curmudgeon
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Chris Smith
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Re: electric motor question

Post by Chris Smith » Fri Sep 30, 2005 8:48 am

Dean
I have done a few my self. I have all sorts of people wanting me to wire their detached work shop for 220, and try to get them to do the major leg work by my instructions, and then I will do the finals. It can be a pain but it usually pays off in the end.

Robert Reed
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Re: electric motor question

Post by Robert Reed » Fri Sep 30, 2005 12:37 pm

Best way to do it is run 50 amp service to new breaker box. Not a bad job--one afternoon should do it.If garage is dry walled , this would make internal distribution a hard job though.

Tommy volts
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Re: electric motor question

Post by Tommy volts » Fri Sep 30, 2005 2:09 pm

krautschmidt <p>Check out the site below for an explanation of the split phase distribution system you probably have in your house. It is very simple but also dangerous for you and your family if you haven't experience at that sort of thing.<p>You may want to consider having a professional electrician do the wiring for your 220/240 outlet.
Split Phase Distribution

EPA III
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Re: electric motor question

Post by EPA III » Fri Sep 30, 2005 7:15 pm

Slow down. You really should not have to rewire the garage. <p>Any motor that is designed for dual voltage operation simply has windings that are wound in two sections. Each section needs 115 Volts. When they are in series, the line Voltage is 230. When they are in parallel, it is 115. In either case, each individual winding has 115 Volts across it and exactly the same current flowing through it: the operation is exactly the same both ways. The speed and power is exactly the same both ways. <p>Parallel, 115 Volt operation DOES require twice the line current because the two windings are in parallel and the currents add together. So any defect in the house or motor windings will have 2 to 4 times the detrimental effect. So I would carefully check these factors before going to the trouble of rewiring the garage. <p>Measure the Voltage at the outlet while the motor is in operation. If it drops by more than a few volts, you have a house wiring problem. If not, look at it at the motor terminals. If it drops there, then look at the wireing in the machine - switch, etc. Tighten everything suspicious. If all that fails, take the motor to a shop and have them test it.
Paul A.

Robert Reed
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Re: electric motor question

Post by Robert Reed » Fri Sep 30, 2005 8:49 pm

If the motor ran OK when previously wired for 220, then all components are good. Check your 120V (parrelel) connections to make sure somthing didn't go amiss here.

Dean Huster
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Re: electric motor question

Post by Dean Huster » Sat Oct 01, 2005 11:20 am

Yes, it does pay off in the end, Chris. I'd much rather have my larger loads such as the jointer, table saw or air compressor operating on 240v. However, the table saw in on wheels for a reason as I have to take it to the job site fairly often, so it has to remain 120v. I guess I could get crazy and wire in a toggle switch to switch it between LV and HV operation, but I can see all sorts of potential problems with that!<p>The key is to get someone else to do the "dirty" work. In my case, to route any juice from the service to a potential shop, I'm going to have to cross septic lines or else add about 500 more feet to the run to skirt the septic system. I don't like shallow lines and don't like the idea of it crossing plumbing that I might some day have to unearth. Sigh. Still, it's going to take at least 500 feet of trencher work at the shortest distance to a good shop location but only 75 feet to my wife's idea of a shop location since she thinks the shop should have electricity, hot and cold running water for a shower and a potty. Wimmin!!<p>Dean<p>[ October 01, 2005: Message edited by: Dean Huster ]</p>
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rixy
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Re: electric motor question

Post by rixy » Sat Oct 01, 2005 1:58 pm

If it runs fine on 240 and you can't get a 240 drop to your shop, see if you can find a beefy step up transformer. I found a couple at the scrap iron yard for 25 bucks each. Rated at 10kv. Fully isolated secondary. I use them for all sorts of projects where I need 240 and all I have is 120. Only caveat - they weigh 145 pounds!
Rick
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