Single Phase Security gate motor humms, replaced cap already

Thread Starter

biglsells

Joined Jul 9, 2019
7
Sorry for my limited knowledge on these motors. I had a security gate that would no longer open or close. Took the motor out because when asked to open or close the gate it would only sit and humm. Tested the run capacitor and it was bad and bulging. Now the gate will happily run and CLOSE the gate but when asked to open the gate it just sits and humms, I can assist by hand spinning to help it get going but it will not open on it's own. I am not sure where to go. Owner did say that this past winter after a snow storm the gate tried to open at the normal time but got stuck on a snow pile and just sat there buzzing until he turned power off and manually opened the gate. Here is a link to a video I took of it trying to run in the "open gate" direction. While it does appear to start here it has zero power to get the gate opening when the belt is on.
 

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CharlesWMcDonald

Joined May 16, 2019
233
It is probably due to a defective reversing switch. You are not getting current to the starter winding when trying to open.
If your motor contains two starter windings then you could also have a winding burned out but I would try the switch first.
 

MaxHeadRoom

Joined Jul 18, 2013
21,412
It is most likely a PSC motor and the reversing is simple SPDT switch.
I would agree it sounds like the cap is not connected when reversing.
In a PSC motor the windings are identical.
Max.
 

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Thread Starter

biglsells

Joined Jul 9, 2019
7
I'm pulling the motor back out shortly and I'll pop the rear cover off and see what is going on and report back, thanks for the ideas.
 

Thread Starter

biglsells

Joined Jul 9, 2019
7
OK - I pulled the motor, what should I be looking for? I don't see any kinds of "switches" here. I thought I might see some kind of centrifugal clutch for start and run but nothing.
 

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LesJones

Joined Jan 8, 2017
2,698
A few points.
1 Are you sure that you have fitted the correct value capacitor ?
2 Assuming it is a PSC motor (As in Max's diagram in post #3) I would expect 3 wires (Plus earth) going to the motor. Is this the case ?
3 Can you measure the resistance of the 2 windings on the motor with it disconnected from the controller. If it is a PSC motor I would expect both windings to have the same resistance.
4 At the motor can you measure voltage between the common of the 2 windings to each of the other ends of the windings in forward and reverse. This is to check that the supply to the motor is correct for both directions. There could be high resistance contacts on the relays that control the motor. (This is assuming mechanical relays. If it uses solid state relays one could be partly faulty. )

Les.
 

Thread Starter

biglsells

Joined Jul 9, 2019
7
Les - the capacitor that I bought was sized by a company online to be the correct one, it looked identical to the one that was on the engine to begin with (I sent the motor plate in for sizing).

There are 5 wires going to this motor in total.

I'll test the motor this week with my meter and post results, thank you very much for the help.

Lawrence
 

LesJones

Joined Jan 8, 2017
2,698
As there are 5 wires to the motor I will assume one of them is earth. This is how I expect the motor is wired.
100719.jpg

To reverse that type of motor the polarity of the feed to ONE of the windings is reversed. The resistance of the auxiliary winding will be higher than the main winding with this type of motor. In the controller there will probably be two multi pole relays (Contactors.). One for forward and one for reverse. It could be that one set of contacts on the relay that is for the opening direction is not making contact so that only one of the windings on the motor is energised.

Les.
 

Thread Starter

biglsells

Joined Jul 9, 2019
7
As there are 5 wires to the motor I will assume one of them is earth. This is how I expect the motor is wired.
View attachment 181377

To reverse that type of motor the polarity of the feed to ONE of the windings is reversed. The resistance of the auxiliary winding will be higher than the main winding with this type of motor. In the controller there will probably be two multi pole relays (Contactors.). One for forward and one for reverse. It could be that one set of contacts on the relay that is for the opening direction is not making contact so that only one of the windings on the motor is energised.

Les.

Les - thank you for the diagram. I'll test the motor and dig into the gate controller shortly and hopefully find out what is going on, will update the thread once I do. Thanks again!

Lawrence
 

Thread Starter

biglsells

Joined Jul 9, 2019
7
Turns out there was a fuse wired up in the control box (not on the schematic, added by someone) in line with one of the wires leading to the motor that was burnt out, replaced that and it worked like a charm!
 

MaxHeadRoom

Joined Jul 18, 2013
21,412
Turns out there was a fuse wired up in the control box (not on the schematic, added by someone) in line with one of the wires leading to the motor that was burnt out, replaced that and it worked like a charm!
Good to hear its fixed.
But!
I would look at correcting what is an obvious mistake by someone.
Max.
 
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