24-02-2012, 03:43 PM
Three-Phase System
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1.1.1: Instantaneous and Average Power
The instantaneous power is the power at any instant of time.
p(t) = v(t) i(t)
Where v(t) = Vm cos (wt + qv)
i(t) = Im cos (wt + qi)
Using the trigonometric identity, gives
1.1.2: Apparent Power, Reactive Power and Power Factor
The apparent power is the product of the rms values of voltage and current.
The reactive power is a measure of the energy exchange between the source and the load reactive part.
1.2: Three-Phase System
3-phase system will produce output of 1.5times of 1phase motor output.
The increase in efficiency from 1phase to 2phase is 41.4%
The increase in efficiency from 1phase to 3phase is 50%
A three-phase system is superior economically and advantage, and for an operating of view, to a single-phase system. In a balanced three phase system the power delivered to the load is constant at all times, whereas in a single-phase system the power pulsates with time.
