GB1170582A - Improvements in or relating to Interference Suppressors for Electrical Equipment - Google Patents

Abstract

1,170,582. Carrying conductors through partitions. NATIONAL RESEARCH DEVELOPMENT CORP. 9 Nov., 1966 [17 Nov., 1965; 17 March, 1966], Nos. 48820/65 and 11685/66. Heading H2E. [Also in Division H3] An interference suppressor comprises a substantially non-dissipative screened low-pass filter network incorporating at least one predominantly inductive series-connected element, and a dissipative end section connected at one end of the said filter network, comprising at least one dissipative impedance element and having conductance sufficient to make the shortcircuited conductance Gsc of the suppressor greater than the modulus of its transfer admittance YT over a range of frequencies which it is required to suppress. In an embodiment, Fig. 1, a terminal bolt 1 passes through an outer tubular conductor 2 connected to a screen 3. Washers 4... 9 are threaded over the bolt, washer 4 being of a material such as ferrite having a high magnetic permeability, washers 5 being of high permittivity dielectric such as barium titanate or lead zirconate titanate, washers 6 being one half the thickness of washer 4 and of the same material as that washer, and washers 7, 8, 9 being of dissipative composite material including resistive particles and/or a substance having hysteresis losses. Fig. 2 shows the equivalent circuit for Fig. 6. In a modification (Fig. 3, not shown), the washers 4 ... 6 are replaced by a single washer having sections of different diameter and made of a material such as ferrite having both magnetic permeability and high dielectric permittivity. In another modification, Fig. 5, the central washer 20 is of a high permittivity dielectric such as a titanate, the washers 21 are of a material having a high permeability such as ferrite and the washers 22 are of high permittivity dielectric half the thickness of washer 20. The washers 7 ... 9 are as Fig. 1.