Motor Inside Box Fan?

[digi001]

What type of motor is inside a standard home box fan?

Single-phase AC Induction Type?

How do the Low, Med, High Fan Speeds work? Does it switch on more poles therefore slowing down the RPM?

 

[srizbf]

a single phase induction motor with capacitor .

 

[digi001]

Cap is for start up?

How do they do the speed control? LOW MED HIGH?

 

[srizbf]

capaciror for start up if it has centrifugal switch
otherwise running.

speed control is usually with a series resistor .

 

[digi001]

so a resistor would change the voltage?

voltage to an induction motor should not effect RPM. you need to accomplish this via frequency.

 

[srizbf]

for low cost box fans , if pole changing type of speed is employed , will not be cost effective.

for such fans , series resistor= reduced voltage and reduce current in wdg and hence reduced torque , leading to reduced speed.

---------- Post added at 10:15 ---------- Previous post was at 08:57 ----------

in my previous post i had:
for low cost box fans , if pole changing type of speed is employed , will not be cost effective.

please read it as:

for low cost box fans , if frequency changing type of speed is employed , it will not be cost effective.

 

[ngochaigv888]

it's singer-phase induction.
amount coiling determined motor speed.
reguler, it have 4 coil and connected in series. including run- speed 1 coil- speed 2 coil- start
2 extremity are run coil and start coil. exremity run coil connected to each wire of AC power. capacity connected to extremity run coil and start coil.
remaining wire of AC connec to speed control device to change connec AC to 1 of 3 point common coils to change voltage on run coil and start coil.
sorry if my english is bad.