When inductive loads such as motors are fed by alternating
current (AC), the variation in current will tend to lag behind the voltage.
In this illustration, the current (pink) lags 30 degrees (one twelfth of a
cycle) behind the voltage (blue). The power delivered at any instant (yellow)
is the current times the voltage.
Set lag to zero and press Calculate to make peak voltage and peak current coincide: this gives the
highest instantaneous power at every stage of the cycle.
If you increase the lag, the delivered power falls even though the current
stays the same; you would have to increase the current to get back to the
required power. The percentage corresponds to the "power factor".
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