Problem with blower motor

F

fsotcher

New member
I installed a Clear Vue, 5HP unit about 9 months ago. The blower is installed as recommended by CV. The motor receives good air flow around it and is protected with a 240V, 30A dedicated circuit. The duct work at the input and the output of the blower is clear. Just today the blower starts up slowly, runs for about 3 seconds and then trips the circuit breaker. I have tried it a number of times with the same results. The motor is not over heating. I opened the input and output duct work with the same results. I have not removed the motor yet so I have been unable to check for binding or the condition of the bearing, but a visual check does not show any problem.

Has anyone had this problem? If so, what did you find? Any ideas?

Thanks,

Fred Sotcher
408-253-7831
fsotcher@gmail.com
 
problem with blower motor

problem with blower motor

Fred,
My guess is a shorted starting capacitor. Try turning the impeller by hand first to make sure it is running free but then I think you will need to pull the unit to get at the starting cap. You can measure it with an ohmmeter (out of circuit). You also should measure the run cap as it is remotely possible it could short. A good cap will show low resistance when you touch the probes but then the resistance will climb as the cap charges. I think yours will read a few ohms at most. Good luck.
bababrown
 
Do you have the cyclone and dust bin installed? Or is this a new install?

It is tempting to try to test the motor/impeller without ducting installed, thinking an unloaded system would provide the lightest load to the motor. However, an impeller with no back pressure will move a tremendous amount of air. The extra air movement requires more current and will trip the breaker. A system with all vents closed will move the least amount of air and requires the least amount of current.

Close off all the vents and block the bottom of the cyclone if the dust bin is not installed yet. This will require less current and hopefully will not trip the breaker.

Steve
 
The motor on my PM2000 3HP had a similar problem a couple months after I bought it that turned out to be the centrifugal switch in the motor. It would do the same thing, run a few seconds at slow speed and then not switch to the high speed. PM finally did replace the motor.
 
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The following response was sent to Clear Vue by email. I believe it was intended to be a response to Bababrown in this thread:

Brobabrown,

I believe you are right. I took out the starting cap, and the top of it was blown off, (not a good sign!). No measurements required.

Thanks,


Fred (fsotcher)
 
The problem with my blower motor problems can cause many driver complaints. Anything from no air circulation to annoying or noisy operation.Can anyone in this forum help to solve my problem??? I'll wait for your reply.
 
Blower Motor

Blower Motor

I had the 5HP blower motor fail for the second time in two years. It tripped the 240V, 30A circuit breaker. The problem is the same as before, a blown out starting capacitor. The capacitor is very hard to get to. I must remove the filter system and reach up above the blower unit to replace it.
This time I replace the 216-259mfd, 220-250VAC unit with a 216-259mfd, 330VAC (Grainger part 2MEP5), in hopes that the higher voltage rating well withstand the start-up voltage spikes better. The new capacitor is larger, so I mounted it in a electrical junction box, connecting it to the motor with SJ cord. I also mounted it in a location that allows me to service it in the future if need be.

Fred Sotcher
 
Fred,
The problem likely is from cycling the motor too often. The cap has both series resistance and dielectric losses. During startup the current through the cap is large and startup lasts for several seconds so a big blob of energy is dumped into the cap. Because they are layered with foil and electrical/ thermal insulator they do not cool well. So the result is heating. If done often enough, the startups will boil the electrolyte and explode the cap. Also, repeated starting is not good for the winding itself. The other thing against cycling the unit is that despite our best efforts dust builds up in the air during any woodworking process and the unit cleans the air between such processes. If you run a particle counter you can watch the air quality degrade and improve. Because of this most of us on the forum discourage cycling the unit. If you still want to cycle the unit look for a cap with the lowest possible ESR.
bababrown
 
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