A silicon diode that changes alternating current to direct current. It is a two-element rectifier that has become the most widely used rectifier for welding power sources. A silicon rectifier performs the same basic function as selenium rectifiers; both materials are used as semiconductors.
The most commonly used silicon redfiers, or diodes, are the 150-ampere diode with a 9.5 or 13 mm (3/8 or 1/2 in.) diameter stud, and the 275-ampere diode with a 19 mm (3/4 in.) diameter stud.
Silicon diodes are stacked into single-phase and three-phase bridge rectifiers in much the same manner as the selenium cells are used. Fewer silicon diodes, however, are required for a given rectifier amperage rating. Silicon diodes must be carefully installed to insure that no strain is placed on the copper pigtail lead. A stress could be introduced into the structure of the diode assembly that could possibly fracture the silicon wafer. Silicon diodes must be carefully matched for voltage and ampere characteristics when they are installed in a main power source. Diodes may be used in parallel to achieve ampere ratings of 1000amperes or more. See SELENIUM RECTIFIER.