GB1530294A - Surge protection circuits - Google Patents

Abstract

1530294 Protective apparatus; electrostatic generators; protecting converters SCIENCE RESEARCH COUNCIL 29 March 1976 [27 March 1975] 13050/75 Headings H2H H2A and H2F In order to protect the components of a high voltage D.C. source 1 from the effects of surges originating in the environment of the output terminal 2 of the apparatus, two resistorcapacitor stages are connected between the source 1 and the output terminal 2, the stage adjacent the output terminal having the shorter time constant. A practical arrangement of the apparatus is shown in Fig. 2 wherein the power source 10 comprises a transformer 13 connected to a Cockcroft-Walton voltage multiplier 15, the output of which is connected to a ceramic type resistor 18. The components of the multiplier 15 effectively form a capacitance C 2 which, together with the resistor 18, form an R/C network R 2 C 2 . The resistor 18 is connected to a series of resistors 20 which form a resistor R 1 , the resistor 18 furthermore being surrounded by a cylinder 19 which is itself surrounded by a cylinder 26. The cylinders 19, 26 constitute a capacitance C 1 which together with the resistors 20 forms a second R/C network R 1 C 1 . The resistors 20 are finally connected to a terminal 12 forming the high voltage output terminal of the apparatus, a spark gap being provided between the terminal 12 and the end plate 24 of the cylinder 26. The two stages in conjunction with the spark gap between the terminal 12 and endplate 24 provides protection against fast and slow surge voltages. Protective apparatus of this type can be used with an electrostatic generator as disclosed in Specification 1,401,182. Such a generator is shown in Fig. 3 and is provided with electrodes 40, 41 each having their own power supplies P/S combined with protective apparatus 42, 43 as shown in Fig. 2.