Ground fault detector for line-powered telephone network
US5774316A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 26, 1996 |
| Grant date | Jun 30, 1998 |
| Priority date | — |
| Expiry date | Aug 26, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/30
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A ground fault detection and line power supply control system protects telecommunication service personnel working on line-powered telephone circuits from ground faults, without requiring that the line power supply be disconnected or shut down prior to a technician working on the line. A ground fault loop sensing current is sourced from an auxiliary DC voltage source that is separate and distinct from the line power supply. This auxiliary DC voltage source is coupled through a ground fault current sense resistor to one side of the powered line, so that detection of a ground fault condition is not dependent upon the supply of current from the potentially hazardous line supply. If a ground fault occurs through either or both of the powered lines, the current flow through the sense resistor will exceed a prescribed threshold, and initiate operation of a switching circuit within the line-powering equipment, thereby rapidly reducing power to the telephone line until the ground fault is cleared or the loop power supply is reset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.