Answer / abhinav yadava

The fan speed is altered using regulators which is
technically increasing/decreasing the resistance to
increase/decrease the supply.In this act,voltage drop occurs
in the resistor not in the line.Hence power consumtion
remains constant.

Answer / ramesh kumar k

A Fan is a constant power device... it always consumes the
same power even if the speed is altered because..

The fan basically operates at 230V and its rated current
inorder to decrease the fan speed we drop some voltage in
the resister so the voltage drop across the armature of the
fan is decreased... because some voltage is dropped in the
resistor itself...

Ex.
Approximately to say...
(this is only example to get understand..)

On 5 No. the Var = 230V & Vr = 0V at current I
On 4 No. the Var = 200V & Vr = 30V at current I
on 3 No. the Var = 150V & Vr = 80V at current I

so like this.... the voltage drop is always 230V only but
we force the less voltage to appear at armature to reduce
the speed of the fan by dropping some voltage in the
resister.

hence the power is always = 230V * Rated current

Answer / amritpal singh

I think the power will not be the same because the
regulator is working as a resistance to the flow of current
also.

Answer / mahesh katakdhond

Fan is resistive load.

In a d.c circuit, if current and resistance are known, power (P=I*I*R) can be determined. This relationship also applied to an a.c circuit. Comment the reason for this.

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