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From: a453 on 31 Jul 2010 18:18

Hi all I have a pump with a 2HP 125 V AC motor. All of a sudden the
motor wont start anymore. If I switch it on it just does a humming sound
and then thermal protection kicks in.

If I initiate the rotation of the motor by hand when the power is on the
motor does start working. The curious thing is that I can make it run
clockwise or counterclockwise by simply initiating the rotation by hand.

My guess is then that some electronic component that "tells" the motor
the direction in which to rotate is now broken and the motor "does not
know" any more wheter it must rotate clockwise or counterclockwise....


What should look in the electronics to try fix the motor? Condensers?
Diodes?....
From: Archon on 31 Jul 2010 19:08
On 7/31/2010 6:18 PM, a453 wrote:
>
> Hi all I have a pump with a 2HP 125 V AC motor. All of a sudden the
> motor wont start anymore. If I switch it on it just does a humming sound
> and then thermal protection kicks in.
>
> If I initiate the rotation of the motor by hand when the power is on the
> motor does start working. The curious thing is that I can make it run
> clockwise or counterclockwise by simply initiating the rotation by hand.
>
> My guess is then that some electronic component that "tells" the motor
> the direction in which to rotate is now broken and the motor "does not
> know" any more wheter it must rotate clockwise or counterclockwise....
>
>
> What should look in the electronics to try fix the motor? Condensers?
> Diodes?....
Start capacitor most likely, they fail fairly often, if its a pool pump
a good pool supplies shop may have them.
JC
From: Jamie on 31 Jul 2010 20:30
a453 wrote:

>
> Hi all I have a pump with a 2HP 125 V AC motor. All of a sudden the
> motor wont start anymore. If I switch it on it just does a humming sound
> and then thermal protection kicks in.
>
> If I initiate the rotation of the motor by hand when the power is on the
> motor does start working. The curious thing is that I can make it run
> clockwise or counterclockwise by simply initiating the rotation by hand.
>
> My guess is then that some electronic component that "tells" the motor
> the direction in which to rotate is now broken and the motor "does not
> know" any more wheter it must rotate clockwise or counterclockwise....
>
>
> What should look in the electronics to try fix the motor? Condensers?
> Diodes?....
if you have a capacitor on the motor or near by in the circuit? try
replacing it.. If you don't have a starting cap, then you may have a
stuck centrifugal switch in side the motor, that is normally located at
the rotor end where the wires go in..

They do make some set ups with external time delay relays that
connects the start winding, this done at times if the motor needs to be
reversed. Most cheaper ones use a bi-metal relay..


From: whit3rd on 31 Jul 2010 21:47
On Jul 31, 3:18 pm, a453 <a...(a)a453.nospam.nospam.com> wrote:
> Hi all I have a pump with a 2HP 125 V AC motor. All of a sudden the
> motor wont start anymore. If I switch it on it just does a humming sound
> and then thermal protection kicks in.

Probably this is a motor with a centrifugal start switch; there's an
'extra' winding that only kicks in at slow revs (or on a cold start)
to get it started in the right direction.

If you're comfortable disassembling the motor, look for springloaded
arms on the rotor, and a push-plate that rubs a rod. That rod
is the switch actuator, look for dirt on the contacts.
There's sometimes a start capacitor in series with the switch,
it's the second suspect if cleaning the switch doesn't solve the
problem.
From: a453 on 1 Aug 2010 15:57
a453 wrote:


Hi thanks to you all for the replies.

I opened the motor.... there is a very rusty capacitor inside it.... the
markings are unreadable.

I disconnected the capacitor and tried to test if the capacitor still
works by using a tester with different ohm settings... I always got no
readings.... I guest that means that the capacitor is broken?

If so, now the problem i getting a new capacitor with the right size...

The motor data is:

dual voltage 125/250 V

Amps 21.0/10.5

2.0 HP (SF 1.10 SF)

This is a single phase Magnetek Centurion SE motor powered at normal 125
Volt housedold power.

My understandi is that i should look for an unpolarized motor star
capacitor rated at 270-324 microFarad at 250 Volt

Is this correct? Thanks so much for your help!!
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