Hows the speed of a Kitchen Mixer or a Ceiling fan is regulated?

[abhi@eda]

hows the speed of a Kitchen Mixer or a Ceiling fan is regulated?

for example assume a AC motor with these below ratings

230V AC 50~ Hz power supply

Power ratings 500Watts 18,000 RPM

so how is the speed regulated in this type of motor?

a high power resistor is used to reduce the voltage or to reduce the current it is receiving?

and my second question is,when the regulator regulates the speed to lower the speed,it actually reduces Voltage or the Current? to reduce the RPM??

and my important question is,When the Rotating Armature of the motor sees some Torque applied to it,it draws more current,the rating of the motor is 2Amps,so any torque on the armature will increase the current consumption,will the motor fail and damage if this happens or it damages itself and also the power supply?

Please explain me in detail ,thank you ...

 

[jpsganesh]

Usually Phase angle control method will be used to control the speed of 1ph AC motors. ex: fan

"Power ratings 500 Watts 18,000 RPM" - I hope it must be universal motor. Ex: mixie
In universal motor we can use the same phase angle control method but mostly different rating tapping from the winding will be taken out and rotary switch or push button kind of switch will be used to shift the supply line from one to another thus changes the speed.

High power series resistor method is very old method. It’ll dissipate more heat and more power wastage.

and my second question is, when the regulator regulates the speed to lower the speed, it actually reduces Voltage or the Current? to reduce the RPM?? - Voltage thus reflects in current. current directly proportional with voltage and load.

Ref phase angle control - https://en.wikipedia.org/wiki/Phase_fired_controllers

For shorter time period motor can run with overload but if it continues motor coil may get damage if there is no protection circuit in the motor line.