Combined mutual drainage reactor and grounding relay

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. When the overvoltage ceases, the reed switches become non-conductive and isolate the drainage reactor from the communication lines. If the line overvoltage and the proportional currents flowing between the open contacts of the switches exceeds a predetermined value and/or persists for predetermined time, the magnetic force on the reed switches will close these switches while such current persists to protect the reed switches from open contact operation in excess of their rated capacity for such operation and to minimize erosion of the switch contacts while conducting current across open contacts.

Dependencies are inferred from the claim text.