We went on a service call for a restaunt exhaust fan motor. The motor was locked up so we replaced the motor with the exact same motor. With in 2 hours the motor quit working, we came back out and it tripped out the thermal overload. So i called the manufactor and suggested a 60 degree celsius motor or upgrading form a 3/4 horse power to a 1 horse power motor. We went with a 1 horse power motor because it was in stock and still had the same out come. The motor is wired correct and the rotation is correct. Any suggestions on what it could be?
Exhaust fan motor over heating
- Thread starter rpeterson
- Start date
- Status
RETRAINDAILY
Senior Member
- Location
- PHX, arizona
bad or improperly sized overloads?
did you up size the over loads when you up-sized the motor?
did you up size the over loads when you up-sized the motor?
mcclary's electrical
Senior Member
- Location
- VA
Welcome to the forum. Is this motor inside of intake air duct work? If so ensure proper airflow through ducts, since that's what cool the motor. Ensure fan spins freely, and megger test the wiring from the breaker to the motor. There's something going on. Make sure it's not a low voltage or voltage drop issue. Perform a FOP test accross the breaker that is feeding this motor and main breaker.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Another real common possible problem:
You have a dual voltage motor, you have it hooked up to the high voltage (460V) connection pattern but have 230 or 208V feeding it. The motor will run, but it won't move much air and as soon as it needs to move more, like when someone opens a damper, it overloads and trips out. Did you double check the connections or just hook it up the way the last guy had it? He may have made the initial mistake and it ran OK for a while until something else changed.
If that's not it, has anything else changed recently?
You have a dual voltage motor, you have it hooked up to the high voltage (460V) connection pattern but have 230 or 208V feeding it. The motor will run, but it won't move much air and as soon as it needs to move more, like when someone opens a damper, it overloads and trips out. Did you double check the connections or just hook it up the way the last guy had it? He may have made the initial mistake and it ran OK for a while until something else changed.
If that's not it, has anything else changed recently?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Agreed with the above advice: Don't assume anything.
When rewiring a deli-kitchen fire-suppression system in an older grocery store, I found that the make-up fan motor had obviously been running in the wrong direction since it had been installed.
When rewiring a deli-kitchen fire-suppression system in an older grocery store, I found that the make-up fan motor had obviously been running in the wrong direction since it had been installed.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yeah, I've seen that too. Some types of blowers will move air in either direction, just a lot more volume in the correct direction. Some pump designs are like that too.
Chev
Master Electrician @ Retired
- Location
- Mid-Michigan
- Occupation
- Retired Master Electrician, Formerly at Twin Lakes Electric and GMC
Another possibility is that the overloads may be "tired" from being tripped frequently and need to be replaced. I wouldn't do anything without checking the amperage that the motor is drawing first. Then go from there.
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