ABSTRACT
Instantaneous current i Instantaneous voltage v Average current Iave Average voltage Vave Maximum (peak) current Imax Maximum (peak) voltage Vmax Current magnitude in root mean square I Voltage magnitude in root mean square V Phasor current in complex form Ī Phasor voltage in complex form V̅ Impedance in complex form Z̅ Apparent power in complex form S ̅ Magnitude of impedance Z Magnitude of apparent power S Instantaneous power ρ Real power P Reactive power Q
The ideal ac circuit has its voltage and current in sinusoidal forms. A voltage waveform is shown in Figure 7.1 and can be expressed mathematically by
v V t= max sinω (7.1)
where v is the instantaneous voltage Vmax is the peak (maximum) value of the voltage ω is the angular frequency t is the time
The unit of ω is radian/second (rad/s) and is expressed by
ω pi= 2 f (7.2)
where f is the frequency of the ac waveform. In places such as North, Central, and South America, South Korea, Taiwan, The Philippines, Saudi Arabia, and Western Japan, the frequency of power supply is 60 cycle/s or 60 Hz. For the rest of the world, including Eastern Japan, the supply frequency is 50 Hz.
