Is the true power on a circuit usually greater than the apparent power? and are they equal in a circuit with both resistance and inductance?

 

Is the true power on a circuit usually greater than the apparent power? and are they equal in a circuit with both resistance and inductance?

consider that circuits perform a wide variety of functions, some where a high value of reactance is desirable, others not. But, generally speaking, unity power is the most desirable, as such, measures are taken to reduce the reactive component as much as possible. If there is any measurable amount of reactive power, then the apparent power will be larger than the real power. Inductive reactance can be negated with capacitive reactance to bring it into unity, where real power and apparent power are equal.

 

Is the true power on a circuit usually greater than the apparent power? and are they equal in a circuit with both resistance and inductance?

True power can never be greater than apparrent power. At unity power factor they are equal. At any other PF, apparrent power is greater.

 

Is the true power on a circuit usually greater than the apparent power? and are they equal in a circuit with both resistance and inductance?

True power is less than or equal to apparent power. They are equal when there is no inductance or capacitance in the circuit.

If the circuit has both inductance (or capacitance) and resistance than the relative value of real power to apparent power is determined by the value of the resistance to the reactive impedance (which determines the power factor).

 

Think of the 'power triangle'...check out this page:

http://www.allaboutcircuits.com/vol_2/chpt_11/2.html