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Calculating the value of the resistance for controlling the speed of AC fan

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i have a single phase ac fan that i would like to control its speed i am a bit new in this field so please bear with me

i had the idea of fixing 3 speeds with 3 switches one for each speed: (25% 50% 90%), and 3 relays each switch activates a relay and each relay wired in series with a resistance of a certain value so we have 3 speeds for every resistance (see the attached image)

i dont know the type of the motor (synchronous , asynchronus ,wound rotor...)

the motor have the following informations: 220 v , 50 Hz , 39W

i didnt make any mesurements (voltage,current..) when the fan is on

my question is am i on the right path for controlling my fan with 3 speeds ?is there a better way ? how to determin the value of the 3 resistances if i want to fix the following speeds (25% 50% 90%)

thank you


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