Why does the power consumed is always constant even if a fan
speed is altered?
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Answer Posted / 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
| Is This Answer Correct ? | 8 Yes | 2 No |
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