DC signaling circuit for use in conjunction with isolation transformers
US4118603A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 31, 1977 |
| Grant date | Oct 3, 1978 |
| Priority date | — |
| Expiry date | May 31, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q3/00
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a DC signaling circuit operatively associated with a communication system having an isolation transformer interconnected between a central communication exchange center and a station site such as a power substation or generating plant where high voltage potential exists. The isolation transformer provides protection from fault conditions that could apply hazardous voltage to a cable pair entering the station. Because of the presence of the isolation transformer, there is no direct path for DC signal functions to pass from the station to the central communication exchange center. Thus, the DC signaling circuit of the present invention is designed to simulate and transfer the simulated DC signals across the isolation transformer to a line side of the communication system leading to the central communication exchange center. DC signals and logic information generated by a signal source such as a telephone on the station side of the isolation transformer can thusly be effectively transferred across the isolation transformer exactly as generated and in a clear and undistorted manner due, at least in part, to provisions in the DC circuit that shunt the wi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.