S
sparkz
right well i've stumbled across a question and i can't figure out what i'm doing wrong.
Q.
At full load a 2Kw, three phase, 4 pole induction motor takes 5Amps at a power factor of 0.7 lagging from a 415V three phase 50Hz source and revs at 1425rpm.
Determine at full load:
i. The power supplied to the motor
ii. The motor effeciency
i have the formula for 1i. to be:
(square route of 3) x Vl x Il x Cos (pheta)
and filling in the formula with figures gives.
(square route of 3) x 415 x 5 x cos 0.7
which = 3593.7W (3.6Kw)
now i have a red circle around the 'cos' which is making the answer wrong meaning Q1ii can't be answered correctly either. so what is meant to go there?
i'm just confused now
any serious help needed.
Q.
At full load a 2Kw, three phase, 4 pole induction motor takes 5Amps at a power factor of 0.7 lagging from a 415V three phase 50Hz source and revs at 1425rpm.
Determine at full load:
i. The power supplied to the motor
ii. The motor effeciency
i have the formula for 1i. to be:
(square route of 3) x Vl x Il x Cos (pheta)
and filling in the formula with figures gives.
(square route of 3) x 415 x 5 x cos 0.7
which = 3593.7W (3.6Kw)
now i have a red circle around the 'cos' which is making the answer wrong meaning Q1ii can't be answered correctly either. so what is meant to go there?
i'm just confused now
any serious help needed.