GB827294A - Excess voltage arrester with quenched spark gap and voltage-dependent resistances with increased protection quality - Google Patents

Abstract

827,294. Protective arrangements. LICENTIA PATENT - VERWALTUNGS G.m.b.H. April 13, 1956 [April 14, 1955], No. 11301/56. Class 38 (4). A device for the protection of electrical installations and apparatus against excessive voltage surges consists of two or more voltage diverters, Fig. 2, connected in parallel, and grouped in close proximity, so that the arc discharge of one diverter ionizes the spark gaps 12 of the other diverters in the group, causing these to operate also. The diverters each consist of a voltage dependent resistor 6 in series with a number of electrodes 8 interleaved with insulating spacers 9. The characteristics of each diverter in any one group may be the same as, or different from, the others in the same group, and, in addition, may be designed so that the operating voltage due to a surge or other H.F. transient is lower than the corresponding operating voltage at power frequencies. The spacing between each pair of diverters in a group must be increased with system voltage to avoid excessive voltage stress between a diverter which has operated, and one that has not. This spacing may be reduced by designing each group for a limited voltage range, and connecting two or more groups in series between the supply and earth. One of the diverters may be arranged to have a lower stacking voltage than the others to pre-ionize the spark-gap to minimize the stacking time of the arrester.