Understanding of impedance, admittance, active power, reactive power, apparent power, average power, instantaneous power, and power factor

 

In an alternating current (AC) circuit, the electrical quantities of interest include the impedance, admittance, active power, reactive power, apparent power, complex power, average power, instantaneous power, and power factor.

Impedance is a measure of the opposition to the flow of AC current in a circuit. It is represented by the symbol Z and is expressed in units of ohms. Impedance is a complex quantity, meaning that it has both a real and an imaginary component. The real component is known as the resistance and the imaginary component is known as the reactance.

Admittance is the reciprocal of impedance and is a measure of the ease of AC current flow in a circuit. It is represented by the symbol Y and is expressed in units of siemens. Admittance is also a complex quantity, with a real component known as the conductance and an imaginary component known as the susceptance.

Active power is the rate at which electrical energy is transferred in an AC circuit. It is the product of the voltage and the component of current that is in phase with the voltage. Active power is represented by the symbol P and is expressed in units of watts.

Reactive power is the rate at which electrical energy is transferred in an AC circuit, but is returned to the source rather than being dissipated in the circuit. It is the product of the voltage and the component of current that is out of phase with the voltage. Reactive power is represented by the symbol Q and is expressed in units of volt-amperes reactive (VAR).

Apparent power is the total power transferred in an AC circuit, including both the active and reactive power. It is represented by the symbol S and is expressed in units of volt-amperes (VA).

Average power is the average rate at which electrical energy is transferred over a period of time. It is calculated by averaging the instantaneous power over a period of time. Average power is represented by the symbol P and is expressed in units of watts.

Instantaneous power is the power at a specific instant in time. It is calculated by multiplying the voltage and current at that instant. Instantaneous power is represented by the symbol p and is expressed in units of watts.

Power factor is a measure of the efficiency of an AC circuit in transferring electrical power. It is the ratio of the active power to the apparent power and is a value between 0 and 1. A power factor of 1 indicates that all the power transferred in the circuit is being used effectively, while a power factor less than 1 indicates that some of the power is being wasted.

By understanding these different quantities and how they relate to each other, you can analyze and understand the behavior of AC circuits and the performance of electrical devices.