125 VAC motor won't start
a453
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?....
Archon
a good pool supplies shop may have them.
JC
Jamie
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..
whit3rd
> 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.
a453
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!!
Archon
Smith motor.
Are there any other identifiers on the motor plate that are readable? If
so go to the AO Smith website
http://www.aosmithmotors.com/default.aspx
Literature library
Manuals
Replacement Parts
Download the parts catalog PDF, it gives all the cap values for motors
but you need some identifier to select the correct part. If you have
the SPA/Pump filter manufacturer it easier to find a good pool supplies
shop and ask, my local pool outfit is pretty good.
JC
Archon
a453
I searched but found no reference to my motor.. it's a bit old.... the
old capacitor is all rusty and unreadable so with some approximation on
"similar " motors I trend to install a new 220v 108-130 MFD
capacitor.... the motor ran fine for a bit and then the capacitor
"popped"... I guess I burned it....
SHould I try use a capacitor with a higher or lower MFD number (the
motor runs on ordinary houseol 115-120volt power) thanks
hr(bob) hofmann@att.net
TRy a higher voltage capacitor.
Jack Myers
A motor starting capacitor is designed to carry AC (alternating current)
when an alternating voltage is applied. Did you perchance substitute a
capacitor rated for 220v DC? That would almost certainly pop.
--
Jack Myers / Westminster, California, USA
Our policy is, when in doubt, do the right thing.
-- Roy L. Ash, ex-president, Litton Industries
bud--
It is common for motors to use a capacitor to start the motor - it is
disconnected by a switch in the motor when the motor approaches running
speed.
Some motors have a capacitor that is permanently connected - a run
capacitor.
Some motors have both a start and run capacitor.
Since the cap died after the motor was running my guess is that the
motor uses a run capacitor. Or the start switch is not opening?
A capacitor that is designed for temporary starting can't be used as a
run capacitor. Your replacement cap was maybe a start cap where a run
cap should have been used? Does the motor have a start switch? Is it
opening? I have never seen a motor with a cap inside.
I think Grainger sells motor caps and you might get an idea of what is
out there. Run caps have a lower mfd rating than start caps.
tm
"bud--" <remove....@isp.com> wrote in message
news:1f8fb$4c598618$cde8d539$37...@DIALUPUSA.NET...
I think you are exactly right about the start switch. The contacts are
likely
welded shut so when the motor starts, the start cap is left in the circuit
until
it overheats and blows. Then the motor will not restart. Also, many of those
start caps have an internal fuse.
Can the OP determine if there is a start switch?
tm
--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---
GrendelsLair
http://www.powertransmission.com/issues/0608/butler1.jpg
As the motor comes up to speed the washer on the left side pushes the
starting switch contacts open.
Start capacitors are for intermittent duty only, i.e. starting the
motor.
Values run from 100-300 MFD and voltages need to be in RMS, not DC
volts.
Jeff
Proteus IIV
TEEHEEHEE
SIMPLE
I HOPE YOU CHANGED THE STARTING CAP BY NOW
SIMPLE SIMON TO THE PIE MAN
NOTHING LESS NOTHING MORE
I AM PROTEUS
stra...@yahoo.com
Didja try just giving it a good 'thwack'? There are some small GE
induction motors used in machines at work that sometimes get cranky
because the start relay is flaky. One smack solves it for a year or
more. No capacitor in this motor, just a relay.
G²
Alan Douglas
>> motor wont start anymore. If I switch it on it just does a humming sound
>> and then thermal protection kicks in.
The motor probably has a starting winding, capacitor, and centrifugal
switch in series across the AC line. As noted, the most likely
problem is the capacitor, but the switch could also be open, possibly
by a bit of dirt between the contacts.
Without the starting winding, yes, the motor will run equally well in
either direction.
Paul Hovnanian P.E.
> 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?
It may be, given your symptoms. But a DC continuity check isn't a good
indication of whether a cap is good or not.
> 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!!
Contact the manufacturer of the appliance that contains the motor. They
should know what size you'll need.
--
Paul Hovnanian pa...@hovnanian.com
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Have gnu, will travel.