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Old 01-18-2013, 07:51 PM   #1
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electric motor


Hi all
just bought new 3hp 230v.single phase electric compressor duty motor.
connected it as per wiring diagram to get cw rotation.
motor tries to start but won't.
reversed the wiring to get it to run ccw, same problem.
checked voltage at receptical, 120 both legs
checked voltage at wire ends at motor, 120 both legs.
this is the second motor same problem. HELP?????

the circuit is controlled by a 20 amp breaker, the wire is 12 gauge to the outlet.

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Last edited by RH913RH; 01-18-2013 at 07:54 PM.
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Old 01-18-2013, 07:59 PM   #2
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What voltage do you get between the two legs?

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Old 01-18-2013, 08:01 PM   #3
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didn't check that will do that right now
250 volts across the legs

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Old 01-18-2013, 08:30 PM   #4
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I would have to guess that you did not wire it according to the wiring diagram or one of your connections is loose.
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Old 01-18-2013, 08:37 PM   #5
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Hi Joed
I checked and double checked the connections
also this is the second motor, same exact problem.
It's a dual capacitor motor. The first time I figured "bad capacitor"
But the same issue with the second, now I'm scratching my head???

It's on a compressor, so I thought it might be the pressure switch so I bypassed the switch and wired directly to the plug, no go.

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Old 01-18-2013, 08:50 PM   #6
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wiring diagram is very clear.
THERE ARE 5 WIRES CLEARLY MARKED P1,T1,T4,T5,T8

CCW---------------------CW

P1----------LINE1--------P1

T1+T5...........................TI+T8

T4+T8----- LINE2--------T4+T5

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Old 01-18-2013, 08:50 PM   #7
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This is not a standard connection, but here's how I believe it should be connected.

One of the incoming lines goes to P1.

T4 and T8 are connected together.

The other incoming line goes to both T1 and T5.

If the motor is wound standard, this will give CW rotation when looking at the back of the motor; normal for an air compressor.

Rob

P.S. If it turns the wrong way, swap T5 and T8.

Last edited by micromind; 01-18-2013 at 08:57 PM.
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Old 01-18-2013, 08:56 PM   #8
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Thanks for the help

It's a harbor freight motor
It's a dual capacitor 3450 rpm
I haven't looked at the capacitor connections
T1 AND P1 the circuit breaker

I did get it to start a couple of times by bumping the circuit breaker quickly on and off

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Old 01-18-2013, 09:00 PM   #9
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Is it still 250 volts while the motor is trying to start?
Jack Hottel
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Old 01-18-2013, 09:00 PM   #10
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Quote:
Originally Posted by RH913RH View Post
Thanks for the help

It's a harbor freight motor
It's a dual capacitor 3450 rpm
I haven't looked at the capacitor connections
T1 AND P1 the circuit breaker
This is where you are going wrong.

Line 1 goes to P1....that is true.

But Line 2 goes to T4 and either T8 or T5 depending on rotation.
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Old 01-18-2013, 09:07 PM   #11
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k-buz
that's how I have it wired.
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Old 01-18-2013, 09:11 PM   #12
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JACK HOTTEL
I didn't check it running
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Old 01-18-2013, 09:16 PM   #13
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micromind
That creates a dead short since P1 and T1 are opposite ends of the overload breaker
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Old 01-18-2013, 09:23 PM   #14
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The motors were gotten from 2 different stores miles apart, I doubt if they were made on the same line at the same time.

Defective capacitor twice????
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Old 01-18-2013, 09:37 PM   #15
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Quote:
Originally Posted by RH913RH View Post
Thanks for the help

T1 AND P1 the circuit breaker
This is the part that is confusing me about your wiring.

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