Amps and motor overheating
When electric motors in good mechanical condition "overheat", does this imply that that they must be drawing more than their rated amps?
The question occurs to me while I'm working on my evaporative cooler, but it seems applicable to motors found in power tools. It would be comforting to know that any tool motor that was drawing its proper amps should be working against the proper load and running at its proper temperature. (I just got a new AC ammeter.) Sounds too simple to be true.
As an HVAC contractor, I can tell you...
Quote:
Originally Posted by
Stephen Tashiro
When electric motors in good mechanical condition "overheat", does this imply that that they must be drawing more than their rated amps?
The question occurs to me while I'm working on my evaporative cooler, but it seems applicable to motors found in power tools. It would be comforting to know that any tool motor that was drawing its proper amps should be working against the proper load and running at its proper temperature. (I just got a new AC ammeter.) Sounds too simple to be true.
The proper amps is not the rated amps on the motor.
The problem with your cooler motor is due to the drive pulley being adjusted too large and the result is too much load on the motor.
We always adjust the drive pulley to keep the motor draw at 50 to 60% of the rated amps. Any more than that and you will cause the motor to overheat.
Whenever we see a motor that is drawing it's rated amps, we know that there is a problem. A motor that is drawing 100% of it's rated amps has a very dim and short future.