Telephone and data overvoltage protection apparatus
US4758920A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 2, 1987 |
| Grant date | Jul 19, 1988 |
| Priority date | — |
| Expiry date | Mar 2, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H9/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Overvoltage protection circuits are provided for coupling a subscriber's station to first and second conductors connected to a telephone system or other similar communications source. The overvoltage protection circuits include first circuitry connected between the first and second conductors for conducting current at a first breakdown voltage and for blocking current below the first breakdown voltage; second circuitry for conducting current at a second breakdown voltage and for blocking current below the second breakdown voltage; and circuitry connected in series between the first and second circuitry for filtering voltage signals on the first and second conductors responsive to the second circuitry conducting current. The overvoltage protection circuits are effective for suppressing noise and transient voltage signals occurring above the data signal and do not require a transient voltage signal to exceed the ring signal for operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.