Sabado, Marso 10, 2012

Instantaneous and Average Power


           Power analysis is of paramount importance. Power is the most important quantity in electronic and communication systems because such systems involve transmission of power from one point to another.

                We will begin by defining instantaneous and average power.

There are several different definitions of power in AC circuits; all, however, have dimension of V*A or W (watts).




Instantaneous power:

  p(t) is the time function of the power,  p(t) = u(t)*i(t). It is the product of the time functions of the voltage and current. This definition of instantaneous power is valid for signals of any waveform. The unit for instantaneous power is VA.


Real or average power:  

P can be defined in two ways: as the real part of the complex power or as the simple average of the instantaneous power. The second definition is more general because with it we can define the instantaneous power for any signal waveform, not just for sinusoids. It is given explicitly in the following expression





The unit for real or average power  is watts (W), just as for power in DC circuits. Real power is dissipated as heat in resistances.
Instantaneous Power p(t) 














Walang komento:

Mag-post ng isang Komento