GB849972A - Improvements in and relating to semi-conductor rectifier units - Google Patents

Abstract

849,972. Semi-conductor devices. ENGLISH ELECTRIC CO. Ltd. May 1, 1957 [May 1, 1956], No. 13367/56. Class 37 A rectifier unit comprises a semi-conductor rectifier element and a resistance mounted in parallel with the rectifier element and arranged to be cooled by a fluid coolant flowing through the assembly. In the embodiment shown in Fig. 1 the resistor is in the form of a tube of conductive rubber or polyvinylchloride 27 through which coolant flows from an electrode assembly in contact with one side of the rectifier element to a basically similar electrode assembly in contact with the opposite face of the element. The first electrode assembly comprises a brass sleeve 10 housing a copper body 15 provided with an annular groove 19 which communicates through radial passages 24 with an internally threaded axial hole 19. In other the electrode assembly the copper body has an externally threaded axial extension 22 adapted to screw into the internally threaded axial hole of the first electrode of an adjacent unit. The electrode assemblies are insulatedly joined by an annular metal and glass seal 12, 13, 14 which forms a sealed housing for a rectifier element consisting of an indium body 18 fused to an N type germanium wafer clamped between the two electrode assemblies. In modified forms of the invention the tube joining the electrode assemblies is of insulating material and the resistance in the form of a helix of wire inserted into the tube and allowed to expand against its inner wall, or of wire wound around the outside of the tube. The unit is expressly designed so that it may be mounted in series with similar units as shown in Fig. 3 between a pair of bus-bars 32, 33. In such an assembly the resistors serve to equalise the inverse potentials across the individual rectifier units. The externally threaded electrode of one of the end units passes through bus-bar 33 and is clamped thereto by nut 35 and to a coolant inlet pipe 36 by a union 37. At the other end of the assembly the connection to bus-bar 32 and to coolant outlet pipe 41 is through the intermediary of a centrally flanged adaptor 38 threaded at both ends. Washers 31, 39 are provided between the flanges of the electrodes of adjacent units to prevent leakage of coolant fluid.