Power and energy measurement in RLC circuits.

The current in a serial RLC circuit amounts to: I = I 0 sin(ωt) Voltage at the terminals of the source: U = U 0 sin(ωt + φ)

Power constant current The power of direct current could be measured using a voltmeter and an ammeter joined according to the schemes shown in the picture. In both systems, the power is equal to: P=U*I

The alternating current power is described in the following patterns: Active power P=U*I*cosφ Reactive power Q=U*I*sinφ Apparent power S=U*I

To measure the active power of alternating current wattmeters are used. In the electrodynamic wattmeter stationary coil the current is connected in series with the receiver of electricity, and the moving coil voltage parallel to the receiver. Active power

Reactive power To measure the reactive power a specialized power meter is used. The reactive power meter is different from a regular wattmeter.

Apparent power Apparent power is the power that appears because of the circuit impedance. Apparent power is the combination of true power and reactive power. To calculate apparent power, you may use either of the following formulas :

The project is realized with the finance support of the European Commission within the "Longlife learning program". The presentation was made as a result of the Leonardo da Vinci project titled "Your future career prospects" carried out in "Zespół Szkół Zawodowych" no 3 in Katowice between 2011 and The publication reflects the standpoint of the authors only and neither the European Commission nor the National Agency bear responsibility for the essential contents included in the presentation and for the way of using the enclosed information.

The end Authors: Michał Bijak Daniel Skupnik February 2012