It's rated at 13 amps at 230 volts. Even at 8 amps it's almost 1800 watts of heater, basically. The power has to be going somewhere.
It's rated at 13 amps at 230 volts. Even at 8 amps it's almost 1800 watts of heater, basically. The power has to be going somewhere.
The calculations here are wrong, they are assuming 0% efficiency ( that means no work gets done, but we know the fans are moving air).
The power that goes directly to heat is the amount left over after the work (sucking dust) is done.
I will grant that the dust ending up in a bin is work and stored energy but, All the air flow continues through the filter and slowly comes to a stop as friction slows it down. I wonder how much useful work a tablesaw yields vs waste heat? Isn't thermodynamics fun.
Bill D
Last edited by Bill Dufour; 08-05-2020 at 11:31 AM.
I assume while the dc is dumping heat into the shop another motor is also running a power tool and dumping even more heat into the shop.
Bill D
An electric motor is roughly 50% efficient so a 750 watt one hp motor uses about 1500 watts of input energy. The extra 750 watts goes to heat. The 750 watts goes into entrophy and thus heat.
Bill D
I'll qualify that. The average universal motor (the kind with brushes) is in the neighborhood of 50% efficiency. Induction motors are much better, probably about 90% for a good 3 HP motor. Large induction motors are around 95% efficient.
Steve's point about stirring up the hot air at the ceiling no doubt adds to the effect, at least in the summer. And any other motor that is running also adds heat. Assuming no exchange of outside air, 100% of the power consumed by any motor & lighting loads in the shop will be transformed into thermal energy, or heat.
If I forget to turn off the lights in my shop overnight, it can raise the temperature by about 4*C by morning. That experiment has been foolishly repeated several times