rpoet
Member
HI All,
A friend and I were having a debate yesterday. Here are the details:
We're using a fractional HP 12vdc gear motor to run a theatrical special effect. The entire triggering of this effect lasts about 2.5 seconds and occurs once a day, max. Cost, time, and mounting space pressures have led to us using a 24vdc power supply for this motor. We turn the motor on and off using a PWM DC drive, and we never have the motor run even near 50% PWM duty cycle.
If anyone's interested, here's the link to the drive we're using:
http://www.dimensionengineering.com/products/sabertooth2x25
My friend is maintaining that we will eventually damage this motor, as it is seeing double its rated voltage, albeit at a 50% or less duty cycle. I maintain that it can't possibly damage the motor, as 24v is not likely to damage the motor's insulation, the PWM doesn't exceed 50%, and the operation time is only seconds.
Further, isn't a motor inherently an "averaging" device, and will run at the speed as determined by the voltage and the PWM duty cycle? In essence, if we were to run the motor at 50% on 24v, we'd see the same behavior and RPM as if we ran the motor at 12v at 100% duty cycle, correct?
I am willing to concede that at some point, the iron in the motor may saturate and heat generation would increase, but I don't think this is happening here (or if it is, it doesn't matter here).
Which one of us is right? Are we gambling and is the motor likely to die an imminent fiery death, or should we not worry?
PS: replacing the power supply isn't really an option right now, as space considerations allow only for the specific PS we have right now and there are other components that require 24v.
Thanks for helping settle this debate!
-rpoet
A friend and I were having a debate yesterday. Here are the details:
We're using a fractional HP 12vdc gear motor to run a theatrical special effect. The entire triggering of this effect lasts about 2.5 seconds and occurs once a day, max. Cost, time, and mounting space pressures have led to us using a 24vdc power supply for this motor. We turn the motor on and off using a PWM DC drive, and we never have the motor run even near 50% PWM duty cycle.
If anyone's interested, here's the link to the drive we're using:
http://www.dimensionengineering.com/products/sabertooth2x25
My friend is maintaining that we will eventually damage this motor, as it is seeing double its rated voltage, albeit at a 50% or less duty cycle. I maintain that it can't possibly damage the motor, as 24v is not likely to damage the motor's insulation, the PWM doesn't exceed 50%, and the operation time is only seconds.
Further, isn't a motor inherently an "averaging" device, and will run at the speed as determined by the voltage and the PWM duty cycle? In essence, if we were to run the motor at 50% on 24v, we'd see the same behavior and RPM as if we ran the motor at 12v at 100% duty cycle, correct?
I am willing to concede that at some point, the iron in the motor may saturate and heat generation would increase, but I don't think this is happening here (or if it is, it doesn't matter here).
Which one of us is right? Are we gambling and is the motor likely to die an imminent fiery death, or should we not worry?
PS: replacing the power supply isn't really an option right now, as space considerations allow only for the specific PS we have right now and there are other components that require 24v.
Thanks for helping settle this debate!
-rpoet