Adjustable line isolation monitor
US3950742A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1974 |
| Grant date | Apr 13, 1976 |
| Priority date | — |
| Expiry date | Oct 21, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/162
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A novel method and apparatus for monitoring an isolated system for ground faults which provides greater sensitivity and accuracy and at the same time does not provide a detector hazard index which would add to the fault hazard index. The monitor connects one of the lines in the isolated system to ground through a non-linear detector. The detector allows current below a predetermined level to flow freely to ground and prevents current which is above a predetermined level from flowing to ground. This is achieved by immediately disconnecting the line in question from ground, by limiting the amplitude of the ground current to the predetermined level, or both. This predetermined current level sensed may be adjusted by the operator. In addition, the monitor includes an alarm circuit which indicates the existence of an unacceptable ground fault in the isolated system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.