[RH913RH]

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.

 

[k_buz]

What voltage do you get between the two legs?

 

[RH913RH]

didn't check that will do that right now
250 volts across the legs

 

[joed]

I would have to guess that you did not wire it according to the wiring diagram or one of your connections is loose.

 

[RH913RH]

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.

 

[RH913RH]

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

 

[micromind]

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.

 

[RH913RH]

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

 

[JACK HOTTEL]

Is it still 250 volts while the motor is trying to start?
Jack Hottel

 

[k_buz]

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.

 

[RH913RH]

k-buz
that's how I have it wired.

 

[RH913RH]

JACK HOTTEL
I didn't check it running

 

[RH913RH]

micromind
That creates a dead short since P1 and T1 are opposite ends of the overload breaker

 

[RH913RH]

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????

 

[k_buz]

Thanks for the help

T1 AND P1 the circuit breaker

This is the part that is confusing me about your wiring.

 

[RH913RH]

P1 comes off one terminal of the overload protector
T1 is attached to the other side of the overload protector and then continues into the motor housing

T1 gets attached to which ever wire (T5 OR T8) isn't tied into t4 and line2

 

[micromind]

micromind
That creates a dead short since P1 and T1 are opposite ends of the overload breaker

You're right. I must be getting old......lol.

How about L1 goes to P1, T1 and T5 are spliced, and L2 goes to T4 and T8.

Rob

 

[RH913RH]

that is how it would be wired for one direction
I have tried both directions, no go

T4 gets spliced to either T5 or T8 depending on desired rotation then spliced to line 2

 

[micromind]

If you have a meter, disconnect 5 and 8, short out the wires going to the start capacitor, and measure resistance between 5 and 8. It should be very low. If it's open, the start switch is stuck open.

The start capacitor will be likely more than 100 µf, the run one will likely be less than 100µf.

 

[RH913RH]

how can I determine the start cap. vs the run cap.??