Voltage regulators are power converters that provide voltage control capabilities. They accept a voltage that varies over a given range and generate an output voltage that does not vary. Unlike integrated circuit (IC) voltage regulators and IC switching regulators, non-IC voltage regulators do not use an active pass element or other semiconductor. There are two basic types of non-IC voltage regulators: switching types and all others, mainly linear and shunt types. Unlike a switching voltage regulator, a linear voltage regulator or shunt voltage regulator is limited by the fact that its output voltage must remain less than its input voltage. Also, the efficiency of most switching regulators is better than that of an equivalent linear or shunt regulator.
Specifications for Phase and Frequency
Voltage regulators carry specifications for phase and frequency. There are two choices for phase: single-phase and three-phase. Single-phase voltage regulators are used with computers, office equipment, and many types of laboratory instruments. Most standard commercial voltages are single-phase. Three-phase voltage regulators are used mainly with industrial motors and industrial machinery. Voltage regulators provide three choices for frequency: 50-Hz, 60-Hz, and 400-Hz. 59-Hz power is used in Europe. 60-Hz power is used in the United States, Canada, Japan, and many other countries. 400-Hz power is used in aerospace applications.
Performance is important to consider when selecting voltage regulators. Parameters include power rating, input voltage, output voltage, and voltage regulation. Power rating is usually expressed in volt-amps, the product of the maximum-allowable RMS voltage and the maximum-allowable RMS current. Input voltage is the nominal line voltage to which the device is connected. The output is a regulated or conditioned voltage. Voltage regulation measures a device's ability to maintain a constant voltage across changes to the input voltage. It is measured as a percentage of the nominal output voltage.
Load regulation, efficiency, and number of outlets are additional performance specifications to consider when selecting voltage regulators. Load regulation is the ability to maintain a constant output voltage with changes in load. It is measured as a percentage of the nominal output voltage. Voltage regulator efficiency is expressed as a percentage of the ratio of the output voltage to the input voltage. Although many voltage regulators supply a single outlet for conditioned power, some feature multiple outlets. This is sometimes the case with equipment that does not consume a great deal of power, such as computers or light instrumentation. With voltage regulators, the number of outlets is not applicable for hard-wired devices or specialty conditioners, such as boards.