High-power precision-stabilized rectifiers

The ratings of the rectifiers discussed vary from 1.4kW at 8A to 112kW at 450A. They are current stabilized to 5 parts in 105 for an 8 hour period or 5 parts in 106 for several minutes. The rectifier is a 6-ph. bridge-connected type, the transformer of which is connected to a motor-driven voltage-regulating transformer. By this means the current output is selected. Stabilization is effected by means of a transistor in series With a d.c. line, the collector-emitter resistance of this being controlled by the base-emitter voltage. A resistor is connected in series with the load and the resistor volt drop compared with a reference voltage. The error voltage is then passed to an amplifier and the output of this provides the transistor base-emitter voltage. The various circuit elements are described in detail together with the care that must be taken in their construction if precise results are to be obtained.