Relay margin test set
US4147901A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 1977 |
| Grant date | Apr 3, 1979 |
| Priority date | — |
| Expiry date | Dec 12, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/323
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Disclosed is a telephone system test apparatus for a telephone switching system having tip and ring circuits which cause a control relay to close upon completion of a path therebetween and which cause the same relay to close upon further opening and closures of the path between the tip and ring circuits. Means monitors such a telephone system for detecting a preselected operative condition therein. Means detects a predetermined impedance condition across such tip and ring circuits. A dial pulse loop circuit is coupled across such tip and ring circuits and it normally has a high impedance condition. Means selectively switches a first low impedance condition around the dial pulse loop circuit upon detection of such predetermined impedance condition and thereby applies a margin test to the first relay. Means opens and closes the dial pulse loop circuit one or more times for applying dial pulses across the tip and ring circuits upon detection of the proper operating conditions and the non busy condition. Means switches a second substantially lower impedance, than the first low impedance, around the dial pulse loop intermediate each opening of the dial pulse loop to thereby ensure prope…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.