SEMICONDUCTOR CONTROLLED RECTIFIER CIRCUIT

1,263,175. S.C.R. circuits. WESTING- HOUSE BRAKE ENGLISH ELECTRIC SEMICONDUCTORS Ltd. 23 June, 1970 [18 July, 1969], No. 36327/69. Heading H3T. [Also in Division H2] One or more parallel connected S.C.R.s 20, 30 are triggered by the regenerative gate current which is produced in a regenerative gate S.C.R. 10 after it has been triggered by a circuit 11, 14, 12. A regenerative (or inverse) gate S.C.R. is triggered by making its gate more negative than its cathode, and once triggered its gate is effectively connected to the anode, thereby providing a positive potential on its gate electrode, with a very short rise time. As shown, this potential is connected through a diode 16 to trigger standard S.C.R.s 20, 30. In an alternative embodiment (Fig. 2, not shown), all the S.C.R.s are of the regenerative gate type and the gate of the first one is connected to the others via a polarity changing transformer (18). Diodes (23, 33) block the initial triggering pulse from the further S.C.R.s and further diodes (22, 32) provide a path for their respective gate currents. The first S.C.R. 10 need not be in the main current path as shown. The application is to power switching to an unspecified load 3, one arrangement switching 20,000 amps at 1000 A/ micro second. The three terminal S.C.R. 10 shown is described in Specification 1,174,899 (Division H1); alternatively a four terminal version may be used as described in Specification 1,263,174.