Line isolation monitor
US3971007A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 1975 |
| Grant date | Jul 20, 1976 |
| Priority date | — |
| Expiry date | Mar 27, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/18
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A line isolation monitor for detecting faults of lines isolated from ground in which a constant current generator generates an electrical signal having one or more frequencies near the power line frequency and applies the electrical signal to the power lines. A signal sensor detects the generated electrical signal on the power line and a discriminator determines the effect of the phase angle of the impedance from each of the power lines conductors to ground and the effect of the relative magnitudes of each of the conductors impedance to ground to detect a fault. A threshold circuit generates an alarm signal if the current flow is above a predetermined level, to energize audible and visible alarms.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.