The rectifier sections are used in all types of industrial applications. Virtually every piece of industrial equipment that has electronic circuitry must have a means of converting ac voltage to dc voltage. These systems use the rectifier circuits discussed earlier to provide the dc power. The rectifier circuits will include capacitors and inductors for filtering, and the combined circuit will be called a power supply. Industrial power supplies will be slightly different from the ones used in consumer products such as radios, televisions, and other electronic components in that their supply will be single-phase and three-phase high voltage. This means that the voltage level will normally be 208 or 480 volts.
It will be easier to understand the operation of these types of power supplies if one examines several specific applications. The next sections will explain the operation of the power supply circuit in two common industrial applications: the ac variable-frequency motor drive and a welding system. This section will also explain the operation of an uninterruptible power supply (UPS) that provides backup voltage to computers and PLCs in case of a power outage.
