# power in ac circuits

#### wizardb4u

Joined Jan 24, 2004
2
i want to discuss about the ac pwer.i want to know what happens to the difference of the power supplied by the source and the power actually available to the loads(apparent power-real power). i am pretty sure that the difference is not equal to the reactive power.

#### eldon

Joined Jan 24, 2004
14
The primary difference between apparent power vs. real power is caused by the phaze relationship between voltage and current in an inductive circuit. As inductive loads, ie. transformers, motors etc., have high inductance, the voltage increases more rapidly than current. This lag in current flow throws off the normal DC power calculation P=EI by a function of degrees lag in I. This is known as Power Factor.

Most heavy electrical users spend thousands of dollars installing capacitor banks which are switched in and out according to inductive load to cancel this imballance at the incomming connection with utility power. This saves far more than the cost of equipment in power lossed as heat due to this condition.