Question about capacitors

Ultradog MN

Well-known Member
Location
Twin Cities
It's been just a few degrees above zero here lately. Garage is unheated.
I turned on an old 1 hp motor yesterday. 220V 1 ph. It is capacitor start.
It wanted to start then quit. Started then quit - several times. So I shut it off.
Could the cold temps be affecting the capacitor somehow and making it so it won't run? It turned on and ran fine when I last used it. Was about 30 degrees then.
 
It may be so cold that the centrifugal start switch mechanism is sticking and not disconnecting the start windings so the overload protector shuts it down. (There's likely a little dab or two of grease in that mechanism, especially in an older motor.
 
I doubt the cold affected the capacitor. Either it's just a coincidence that the start cap died when it got cold, or the lube is cold enough to make the motor drag.
 
Also, if the load is something like an air compressor, the load may be dragging enough that the motor can't get up to speed before it kicks out as mentioned.
 
The cold is affecting the bearings. Wait until it warms to +20 degrees and try it again before you order any parts. I've had that on a couple of my electric motors.
 
Based on my experience with capacitors including motor start capacitors, I think its unlikely cold weather adversely affected the capacitor but instead the cold weather, cold compressor, and its cold oil (or else a loose/burned/resistive connection) caused it to be harder to crank up.

An actual true Capacitor tester could be used but you may want to at least inspect all the motor and especially capacitor connections, I have seen many get loose burned and resistive...


John T Noooooo warranty its been over 50 years since I was an Engineer at the Century Electric Motor Company and Ive slept since lol

God Bless America, keep her safe strong and great
 
I would bet it is over torquing due to the cold on the hinges or they are frozen.

I would unhook the latch and make sure you can manually move the door.
 

Yep. Ditto on the heat lamp. I need one in the morning to get my bones started. Thank you for heated car seats. There was a time that if a car dealer tried to sell me heated seats with a car for another dollar, I would have told him to take a hike. Once I got a car with them then I can't do without them. Keep them on all the time, even in the summer sometimes.
 

Out of curiosity, what is the motor attached to?

You haven't said and others have assumed it's a compressor or garage door opener.

Confusing thread to say the least.
 


To add to previous post, I got the impression the motor was not attached to anything and that Ultradog MN simply tried the motor which didn't work.

Clarity is important.


Why does the edit function here not work?
 
It's on a decrepit old Leblond lathe.
I took the tailstock off of it as it's got
a lot of taper. Brought it into my tiny
office which is heated and took it apart
and cleaned/derusted/lubed the bottom and
adjuster screws. Put the tailstock back on
the lathe and flipped the motor on just for
kicks. It was in low gear and no load but
wouldn't run right.
 
Taper is often a result of offset in the tailstock base. There are gibs (adjustment screws) to move it away and toward the operator. I like to use a piece of accurate round stock about .375" diameter in the tailstock Jacobs chuck, put into the primary 3 jaw, and then adjusted to be aligned when the 3 jaw id tightened. Jim
 
The capacitors can be checked with an ohm meter. On ohms setting with the capacitor disconnected from the motor and power USing the leads on the meter touch them to the contacts on the capacitor then switch the leads if it jumps up and drops back rather quickly both time it is good if it does not act in this manner it is probably shot.
 
I have seen caps and transistors not work in extreme cold. The caps can change value enough to affect oscillators to the point they dont fire or run. Same with transistor bias and fe change enough to mess up a circuit below freezing. Lots of heathkit electronic ignitions come to mind.
 

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