Abstract: A combination mutual drainage reactor and grounding relay for protection of a two-wire communication circuit comprising a pair of inductively coupled coils each having one end grounded and the other end connected to a corresponding communication line through one of a pair of magnetically operated, normally open S.P.S.T. gas-filled reed switches which are disposed in the common magnetic circuit of the two coils and which have predetermined voltage breakdown characteristics between their open contacts.A voltage from one line to ground in excess of the breakdown voltage characteristic of the connected reed switch causes current flow across the open switch contacts and through one coil to ground. The voltage thus impressed across this coil produces an equal voltage across the other magnetically coupled coil, which, in turn, causes the other reed switch to conduct, thereby preventing abnormal line-to-line voltage and maintaining balanced line-to-ground voltages.

Abstract: A neutralizing transformer comprising a flat ribbon-like conductor cable having a plurality of flexible conductors, either flat or round, encapsulated in insulation with a flexible conductor shield or ground plane coextensive with the width of the cable, said transformer being formed by coiling such flexible ribbon-like conductor cable and utilizing the shield as the transformer primary with the flexible conductors as the secondaries. The secondaries may be connected in various ways to reduce the mutual capacitance between the conductors while at the same time maintaining a high dielectric withstand capability between the conductors.

Abstract: A neutralizing transformer arrangement having its primary winding connected in series with a D.C. blocking capacitor. The primary circuit is preferably series resonant at the power frequency (60 HZ), the capacitance of the series resonant circuit being provided by the D.C. blocking capacitor and, to some extent, by inter-turn, interwinding and distributed winding capacitances. The neutralizing transformer includes an input cable composed of one or more twisted pairs of wires over which communication frequencies signals pass. Each wire of a twisted pair is wound on opposite outer legs of the core of the transformer. A similar pair of isolating windings is wound on the same outer legs. The primary winding is wound about the central leg of the core of the transformer as is the one or more twisted pairs.