Protection and recovery of telephone line interface circuits
US5390231A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 1, 1993 |
| Grant date | Feb 14, 1995 |
| Priority date | — |
| Expiry date | Apr 1, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/18
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An automatic protection and recovery method for a telephone line interface circuit is described. The interface circuit monitors current on the line, and in the event of a fault producing an excessive current a protection relay interrupts a connection of the interface circuit to the line, and the interface circuit monitors common mode voltage on the line. The interface circuit is reconnected in response to the monitored voltage being below a relatively high threshold. If a second interruption results, the interface circuit is then reconnected in response to the monitored voltage being below a lower threshold. If a further interruption results, the interface circuit enters a ground fault recovery process. The method facilitates protection and rapid recovery from arbitrary fault conditions on the telephone line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.