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Reduce AC current to motor

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Lak

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hello,

I need to reduce the current drawn by a ac bi-directional torque motor.
- 240V 50Hz, 20Nm torque single phase.

3 wires - clockwise ,anticlockwise, neutral.

The motor is direct triac control ie. on and off.
Currently, the motor draws 0.4A rms 220Vac in one direction.
How do I reduce the current to 0.2A 250Vac - by rule of thumb ?
How to connect the components...resistor / inductors and what wattage of components ?
Just would like to know / solicitate opinions from expert power engineers here. Any info you still need that I've left out ?

thanks ..lak
 

If you want to reduce current, attach serial two resistors with coils wire (on each side put one to reduce disipation power). Serial resistance of resistors must be equivalent with impedance of coil. If your coil have impedance, for example 2oms use 2x1oms resistors. On this way you will have half of the started curent.
 

I'm not an expert power engineer, but if you will half the current of the motor you will also reduce drastically the torque of the motor.
 

Hi
yes marie65, i think that u r right .the torque depends on the current mainly .
while the speed depends on the average voltage .
right?

Best regards
hindi
 

HINDI, you're right. The speed of a motor depends greatly on the supply voltage. V = IR + kw. At no load, IR is negligible, so, V = kw, where w is angular velocity of the rotor.
 

better to do PWM along with IGBT's, which maintains the torque. Using TRIAC's will effect the torque very much
 

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