Power Voltage Current Triangle

Active reactive and apparent power.

Power voltage current triangle. We know that reactive loads such as inductors and capacitors dissipate zero power yet the fact that they drop voltage and draw current gives the deceptive impression that they actually do dissipate power. The cosine of angle between the voltage and current is called power factor cosϕ. The value of power factor is 1 for pure resistance and 0 for pure inductor capacitor. In a simple alternating current ac circuit consisting of a source and a linear load both the current and voltage are sinusoidal if the load is purely resistive the two quantities reverse their polarity at the same time at every instant the product of voltage and current is positive or zero the result being that the direction of energy flow does not.

In an inductive circuit the power factor in lagging nature. Then real power is the i 2 r resistive element measured in watts which is what you read on your utility energy meter and has units in watts w kilowatts kw and megawatts mw. Also in pure capacitive circuit the current leads the voltage by 90 deg. Note that real power p is always positive.

Where real power p is in watts voltage v is in rms volts and current i is in rms amperes. For example in an open circuit condition voltage is present but there is no current flow i 0 zero therefore v 0 is 0 so the power dissipated within the circuit must also be 0 likewise if we have a short circuit condition current flow is present but there is no voltage v 0 therefore 0 i 0. Power within an electrical circuit is only present when both voltage and current are present. Power triangle is the representation of a right angle triangle showing the relation between active power reactive power and apparent power.

This phantom power is called reactive power and it is measured in a unit called volt amps reactive var rather than watts. 2 power factor is defined as the cosine of angle between the voltage and current phasor. The mathematical symbol for reactive. 3 the angle ø between ab and ac in power triangle represents the angle by which current is lagging.

It is denoted as pf and given as.