Mark Bolton
11-20-2017, 4:25 PM
We have a sander with a 240V single phase 5Hp TEFC motor on it. I cant say that I ever really notice it til now but I guess in hind sight the sander was perhaps getting louder (somewhat of a growling sound) over time. Never peaked my interest. But then the amp meter on the sander started to climb. Couple times employees would say no matter what they did they couldnt keep it out of the red on the meter. This was again over time. Finally we were running some material on Saturday and I noticed the amp meter riding constantly on the high side of normal (around 28-30 amps). Motor is rated at 25 and I cant say I know for sure but I really think I remember it no-load idling at less than 20.
I thought for sure we had a run capacitor going south. So I pulled the cover off, check the capacitor spec's, and for the heck of it I popped the belts off the motor sheave and started the motor with zero load. Same high amperage condition, same growling, (idling at 22-24 amps with nothing connected to the motor shaft). I did this trying to rule out a bad bearing up top. The motor shaft is rock solid, no radial or end play, and spins as free as a bird.
Swung by Grainger this morning and picked up a new 370V 50Muf run capacitor. Came back to the shop, installed the cap. and while it was apart stuck in a fresh set of belts, hit the button and unblievably it showed the exact symptom of a bad START capacitor? It tried to start, rocked back and forth a few times, and tripped on overload. So I reset the overload and hit the button and gave the drums a roll by hand and it fired right up AND ran quieter than ever but still with moderately high amps (about 20-21).
I started it several times rolling by hand and headed back to grainger for a new start capacitor (should have just bought both the first time). Got a new 125VAC 600Muf start capacitor, back to the shop, stick it in, re-tension the belts, and the thing fires right up. It is still no-load idling at 20-21 but its running fine, and sanding is seemingly fine.
Im wondering if the motor is on its way out? Why was it starting with the old start cap. and when switched the run cap. the start cap then seemed bad?
We are planning to just watch it but we have a slew of work coming up and Im wondering if I shouldnt just order a replacement motor to have on hand but hate to toss 600-700 bucks out the window if its not needed.
Appreciate any of you motor guys input.
I thought for sure we had a run capacitor going south. So I pulled the cover off, check the capacitor spec's, and for the heck of it I popped the belts off the motor sheave and started the motor with zero load. Same high amperage condition, same growling, (idling at 22-24 amps with nothing connected to the motor shaft). I did this trying to rule out a bad bearing up top. The motor shaft is rock solid, no radial or end play, and spins as free as a bird.
Swung by Grainger this morning and picked up a new 370V 50Muf run capacitor. Came back to the shop, installed the cap. and while it was apart stuck in a fresh set of belts, hit the button and unblievably it showed the exact symptom of a bad START capacitor? It tried to start, rocked back and forth a few times, and tripped on overload. So I reset the overload and hit the button and gave the drums a roll by hand and it fired right up AND ran quieter than ever but still with moderately high amps (about 20-21).
I started it several times rolling by hand and headed back to grainger for a new start capacitor (should have just bought both the first time). Got a new 125VAC 600Muf start capacitor, back to the shop, stick it in, re-tension the belts, and the thing fires right up. It is still no-load idling at 20-21 but its running fine, and sanding is seemingly fine.
Im wondering if the motor is on its way out? Why was it starting with the old start cap. and when switched the run cap. the start cap then seemed bad?
We are planning to just watch it but we have a slew of work coming up and Im wondering if I shouldnt just order a replacement motor to have on hand but hate to toss 600-700 bucks out the window if its not needed.
Appreciate any of you motor guys input.