It is the opposite of DC, or direct current, and the electricity reverses direction back and fourth at regular intervals, generally multiple times per second. This alternation is measured in Hertz; in the United States and many other countries, AC power is generated at 60 Hertz, meaning the current alternates 60 times in a second.
Most power plants generate AC electricity rather than DC electricity. Power lines, held up by telephone poles that are connected to every residential building and most commercial, carry high voltages of AC power. However, the higher the voltage, the more insulation it requires. Most alternating power is converted inside buildings because many appliances only run on DC power, including printers, laptops, battery chargers and desktop computers.
Other electrical devices found in the home, like lamps, radios, fans, televisions and small appliances run off the electricity directly from the wall outlets, which is the AC power. In industrial applications, devices and machinery like generators, dynamotors, inverters and transformers all use AC power to operate. AC current can also be used in telecommunications to convey information instead of electricity. They are used in radio and telephone lines.
The wavelength of AC power is always a sine wave, which exhibits smooth, repetitive oscillation. The rate of changing direction is called the frequency, which is measured in Hertz. 50 Hertz, for example, refers to the number of back and fourth cycles each second. The frequency of the wave can be increased or decreased dramatically by a transformer, which increases the frequency when the wave must travel great distances.
AC power supplies generally have adjustable output settings for component response testing at different voltages, currents and frequencies, since each application requires different amounts of each because of many different factors, such as distance traveled and maximum voltage. These are also used in testing motors and other electrical equipment whose input valves may vary. AC power comes from a variety of configurations, including bench top, DIN rail, rack mounted and cabinet styles.