Protection arrangement for a telephone subscriber line interface circuit
US4947427A · kind A · utility
21Cited by
7References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 12, 1989 |
| Grant date | Aug 7, 1990 |
| Priority date | — |
| Expiry date | Oct 12, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/087
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A telephone subscriber line is connected to a SLIC via contacts of an isolation relay. Line voltage on the line side of the relay contacts, and line current on the SLIC side of the relay contacts, are detected during opposite polarity half-cycles of an a.c. fault on the line, and the contacts are opened to protect the SLIC if the voltage and/or current is excessive. The interruption of current causes the line voltage to rise to maintain the protection for the duration of a fault.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.