Electrical Power

October 13, 2018 Electrical Theory, Robotics Theory,

Electrical Power:

Electric power is the rate per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is Watt.

$P={\text{work done per unit time}}={\frac {VQ}{t}}=VI\,$

where,
Q is electric charge in Coulombs
t is time in Second
I is electric current in Ampere
V is electric potential or voltage in voltage in Volts.

Resistive Circuits:

In the case of resistive circuits, Joule's law can be combined with Ohm's law(V = IR) to generate expression for power dissipated.

$P=IV=I^{2}R={\frac {V^{2}}{R}},$

where,

R is electrical resistance.

Alternating Current:

Energy storage elements such as inductance and capacitance may affect the direction of energy flow in the case of alternating current circuits.

The portion of power flow that averaged over a complete cycle of the AC waveform results in net transfer of energy in one direction is real power(active power).
The power flow due to stored energy that returns in each cycle is reactive power.

The real power P is Watts consumed by a device is given :

$P={1 \over 2}V_{p}I_{p}\cos \theta =V_{rms}I_{rms}\cos \theta \,$

The relationship between real power, reactive power and apparent power can be expressed by representing them in vector form: