i have a 1750 rpm 1/2 hp electric AC motor. I know that decreasing the voltage to slow the motor speed down is bad because it will put a load on the motor and prematurely burn it up. Im using the motor to drive the agitator in a homemade insulation blowing machine, the agitator is moving ridiculously fast and would take an arm off!!! any ideas on how to slow it down???? pulley systems are almost out of the question because the driven gear is already almost as big as the machines' housing (in diameter). Cooling seems to be the main concern, i wonder if theres a way to lower the voltage and increase the cooling capacity......hmmm
PWM? Can you send pulses to the motor (pulse width modulation) as oppsed to direct current the whole time? By controlling the pulse you can vary the speed. Otherwise you could add some big resistors to drop the voltage, but make sure they are rated for enough power (I*V - depending on your current) so they don't burn out.
you could try a adding a second smaller motor that drove a dedicated fan. Direct the air flow from that through the main motor and the flow of cooling air is independent of the main motors rpm. I don't know how fixed your design is. If design can be changed, worm drives can achieve fairy high speed step down ratios in small spaces.
It sounds like you need a 175 rpm motor, or there abouts. It is not practical to slow that motor that much, by supplying it with 6 hertz ac, or by cooling the motor. You need a gear motor or a pulley system; perhaps a worm gear. PWM = pulse width modulation is for DC motors. Neil
This Site Might Help You. RE: slowing down an ac electric motor? i have a 1750 rpm 1/2 hp electric AC motor. I know that decreasing the voltage to slow the motor speed down is bad because it will put a load on the motor and prematurely burn it up. Im using the motor to drive the agitator in a homemade insulation blowing machine, the agitator is moving...
yes , i think that u want to use an AC motor 1/2 hp and 1750 must be 60 Hz and with 2 couples of poles at the maximum load as u say decreasing the voltage will decrease the rotation of motor but also decrease the max load ability of the motor so the first load in the nominal voltage will be overload in the Second voltage and it pulls more current( ac motor's characteristics) that may burn your motor and the resistance will not good (latter problem ) so what we can do to decreasing motor's speed without decreasing its torque?4 ways, 1. decrease the frequency by power-electronic devices or motor-generator systems this is the classical way but not economical for you 2. replacing the motor with another, which has more poles , u can buy a 875 rpm AC motor with 4 couples of poles with same nominal power ( it will be a little larger) 3. u can use a gear box 4. u can replace the motor with a DC motor (with rectifier )and simply control it with input voltage
