I have a 1 HP induction motor with capacitor start and capacitor run. As I
understand the function, the start capacitor circuit is engaged at start up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute or
so it will start and run fine again. Any ideas on what could cause this?

One thought would be a bearing close to failure. Can you lube the
bushings/bearings? What is being driven by the motor? Could it be
external to the motor or is the motor freerunning when it happens?
Respectfully,
Ron Moore

"JimInsolo" wrote in message
link.net...
I have a 1 HP induction motor with capacitor start and capacitor run. As I
understand the function, the start capacitor circuit is engaged at start
up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute
or
so it will start and run fine again. Any ideas on what could cause this?

That sounds like the centrifugal start switch is not staying open and it is
connecting start cap(s) back into the start configuration. First look at
the start push button and make sure it is not trying to restart. Then open
the motor and take a close look at the centrifugal switch. Either switch
may be involved.

Bob Swinney
"JimInsolo" wrote in message
link.net...
I have a 1 HP induction motor with capacitor start and capacitor run. As I
understand the function, the start capacitor circuit is engaged at start
up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute
or
so it will start and run fine again. Any ideas on what could cause this?

Starting cap switch is hanging up. Pull the motor apart, take a look at
the switch assembly on the end of the shaft. Odds are good that the
contacts are horribly burned.

JimInsolo wrote:
I have a 1 HP induction motor with capacitor start and capacitor run. As I
understand the function, the start capacitor circuit is engaged at start up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute or
so it will start and run fine again. Any ideas on what could cause this?

"JimInsolo" wrote in message
link.net...
I have a 1 HP induction motor with capacitor start and capacitor run. As
I
understand the function, the start capacitor circuit is engaged at start
up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute
or
so it will start and run fine again. Any ideas on what could cause this?



I have only had this problem with import electric motors that are new and
only when the room temperature was near freezing. I get the impression that
the starter circuit is not disengaging because it got stuck because of low
temperatures. If I tried to start the motor and it acted up, then I would
turn it off and try it again after a few moments. I had to do this several
times until the internal heat of the motor warmed up the starting circuit.
Once it got warmed up it would work fine. When I heated the shop I never had
the problem again.

If you check inside the motor, you will probably find the centrifical switch
is used up and not making good contact when the motor stops.
Steve

"JimInsolo" wrote in message
link.net...
I have a 1 HP induction motor with capacitor start and capacitor run. As I
understand the function, the start capacitor circuit is engaged at start
up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort of
vibrating racket and blow the breaker. Sometimes if I just wait a minute
or
so it will start and run fine again. Any ideas on what could cause this?

Guys-
thanks for all the input- found that indeed the centrigugal switch was
sticking, did a little cleaning and lubed it and all seems OK so far.
"Steve Lusardi" wrote in message
...
If you check inside the motor, you will probably find the centrifical
switch
is used up and not making good contact when the motor stops.
Steve

"JimInsolo" wrote in message
link.net...
I have a 1 HP induction motor with capacitor start and capacitor run. As
I
understand the function, the start capacitor circuit is engaged at start
up
and then dis-engages when the motor reaches full speed. The motor works
fine most of the time, but every so often it will make a terrible sort
of
vibrating racket and blow the breaker. Sometimes if I just wait a
minute
or
so it will start and run fine again. Any ideas on what could cause
this?