Power Rectifiers Information
Power Rectifiers Information
Power rectifiers are electrical devices that convert alternating current (AC) to direct current (DC). They are an integral part of telecom rectifiers for the telecommunications industry, and in battery chargers, DC power systems, and other power system devices. Power rectifiers include one or more diodes, electronic components that conduct current in only one direction. Single-diode power rectifiers omit the negative portion of the AC waveform. By contrast, multi-diode power rectifiers reverse the negative portion of the AC waveform, allowing it to merge with the positive part to produce an entirely positive current. Typically, single-phase power rectifiers use four diodes. If the AC is center-tapped, then the diodes are arranged anode-to-anode or cathode-to-cathode to form a full-wave rectifier. If the AC is not center-tapped, then the four diodes are arranged in a bridge. With three-phase AC power, six diodes are used. Each of the three pairs is arranged in series. Many diodes have four terminals so that they can be used in a single-phase split supply, a half-bridge, or for three-phase use.
Power rectifiers vary in terms of AC inputs and DC outputs. Common AC input voltages include 115, 208, 230, or 480 VAC. Common AC input frequencies include 50, 60, and 400 Hz. Important output specifications include DC output voltage, DC output current, power, and efficiency. Typically, bridge rectifiers produce a voltage output that is approximately twice that of a conventional full-wave circuit. For example, with three-phase AC power, double-diodes can produce six pulses of DC for three phases of AC. Three-phase bridge rectifiers can deliver power outputs up to 500 kW at 500 VDC. For low voltage, high current applications, an inter-phase transformer (IPT) can be used to interconnect a pair of three-phase, three-pulse rectifiers.
There are several mounting styles for power rectifiers. Some devices mount on a standard DIN rail or can be attached to a wall, cabinet, or chassis. Others feature an open frame or enclose the input and output connections. Through hole technology (THT) mounts power rectifiers on a printed circuit board (PCB) by inserting component leads through holes in the board and then soldering the leads in place on the opposite side of the board. Surface mount technology (SMT) adds components by soldering leads or terminals to the top surface of the board. Rack-mounted power rectifiers include hardware such as rail guides, flanges, and tabs. Many rack-mounted devices fit a standard 19” telecommunications rack. Rack mount sizes include 1U, 2U, 3U, 4U, and 5U.
Power rectifiers are used in variable-speed DC drives, battery chargers, and DC power supplies. They are also used in signaling, switching, electroplating, electrocoating, and processing applications. Low voltage devices are used in the ignition assemblies in automobiles. High voltage devices are suitable for military and aerospace applications.