summary
● AC is the most commonly used type of electricity.
● AC consists of current flowing in one direction and then reversing and flowing in the opposite direction.
● One revolution of an AC generator is called a cycle.
● The two halves of a cycle are referred to as alternations.
● Two complete alternations with no reference to time make up a cycle.
● One cycle per second is defined as a hertz.
● The waveform produced by an AC generator is called a sinusoidal waveform or sine wave.
● The peak value of a sine wave is the absolute value of the point on the waveform with the greatest amplitude.
● The peak-to-peak value is the vertical distance from one peak to the other peak.
● The effective value of AC is the amount of current that produces the same degree of heat in a given resistance as an equal amount of direct current.
● The mathematical process called the root-mean square (rms) process can be used to determine the effective value.
● The rms value of a sine wave is equal to 0.707 times the peak value.
● The time required to complete one cycle of a sine wave is called the period (t).
● The number of cycles occurring in a specific period of time is called frequency (f).
● The relationship between frequency and period is:
● Square waves are composed of the fundamental
frequency and all odd harmonics.
● Triangular waveforms are composed of the funda- mental frequency and all odd harmonics 180º out of phase with the fundamental frequency.
● Sawtooth waveforms are composed of both even and odd harmonics, the even harmonics being 180º out of phase with the odd harmonics.