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Motor Puzzle #215402 05/04/15 07:46 PM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline OP
Member
I have a Gast blower/ Emmerson motor that has 'issues.'

0) 1 Phase motor, nominal 1hp, NEMA 42C frame design,

1) Wiring is okay -- new machine -- no shorts -- no opens.

2) Has typical Klixon thermal protection which appears to also be okay... N/C across all three contacts.

3) Has both run windings and start windings: dual voltage 240/120 VAC with classic six wire lead outs/ taps at peckerhead.

4) It has a capacitor 'footprint' that is obviously tied into the start windings... in series, naturally.

5) There is no second capacitor in its design.

6) There is NO Centrifugal Switch to cut out the start winding.

7) There is no apparent room on the shaft to mount a centrifugal switch. (!)

I've known Split-Phase motors that have no capacitor yet do have a start winding and a centrifugal switch.

This scheme is the reverse: no switch while having a capacitor.

I have yet to track down a wiring diagram that is anything other than a tap connection pattern. (ie 120VAC wiring and 240VAC wiring connections.)

I can't find any reference to a motor of this design.

Larger Gast blowers/ Emmerson motors use cap-start// cap-run schemes -- WITH a centrifugal switch.

I have one.

The Klixon does not appear to have any solid state/ trick capability to cut out the start winding. If it does, -- it's not working on this machine as intended.

In all of the Klixon liturature, there is absolutely no reference to solid state switching -- as would be required to replace a centrifugal switch.

&&&&&&&

Ultimately, is this a motor that was built up by sleepy troops that slipped by quality control or is a component ruined?

In all respects, this blower looks to have never been placed into service at any time. It looks pristine -- ready for a photo-spread.

Comments appreciated.

Last edited by Tesla; 05/04/15 07:46 PM.

Tesla
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Re: Motor Puzzle [Re: Tesla] #215403 05/04/15 09:28 PM
Joined: Mar 2004
Posts: 947
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twh Offline
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Permanent split capacitor motor. No start switch.

Re: Motor Puzzle [Re: Tesla] #215405 05/04/15 11:16 PM
Joined: Jul 2004
Posts: 9,409
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gfretwell Offline
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Is it possible this motor uses an external start relay. (3 wire connection) IBM used lots of them because the dust in old card equipment would trash a centrifugal switch pretty fast.


Greg Fretwell
Re: Motor Puzzle [Re: Tesla] #215406 05/04/15 11:45 PM
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Posts: 1,273
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Tesla Offline OP
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twh...

That's the best fit.

Thanks.

First time I've ever dived into such a beast. Strangely, this critter is missing from most textbook tabulations of motor types. They jump straight off to cap-start/ cap-run schemes.

Professionally, I've just brought the field wiring to motors... the vast bulk of which have been three-phase -- and the occasional one-phase HVAC gizmo.


Tesla
Re: Motor Puzzle [Re: Tesla] #215407 05/05/15 01:06 AM
Joined: Mar 2004
Posts: 947
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twh Offline
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So, why doesn't it run?

Re: Motor Puzzle [Re: Tesla] #215408 05/05/15 06:02 AM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline OP
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As shipped off of eBay...

Had the wrong capacitor installed -- way too large -- causing astonishing circulating currents in the rotor, itself.

This was on top of sick bearings.

I believe that it stood as a spare far, far, too long and its bearings became gooy and tight.

That's enough drag at spool up to cause the prior owner to start fiddling with the capacitor rating.

The bearing -- 6203 is the single most common one made -- and is priced cheap.

With fresh bearings -- it will be off and running. Right now the stiff bearings are popping the Klixon.






Tesla
Re: Motor Puzzle [Re: Tesla] #215410 05/05/15 12:23 PM
Joined: Jul 2004
Posts: 9,409
G
gfretwell Offline
Member
Yup, in quantity, I get those 6203s for less than $2 each.
You are right, they are used in most pump, blower and other 5/8" (nominal) shaft motors. It is actually a metric size.


Greg Fretwell

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