Backup protection switch to prevent reverse power flow in a UPS
US4763014A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 21, 1987 |
| Grant date | Aug 9, 1988 |
| Priority date | — |
| Expiry date | Sep 21, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02J9/062
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A UPS system includes a mechanical backup input line isolation switch to provide mechanical isolation between the primary energy source connected to the input line and the secondary energy source upon detection of a failure of an electronic isolation switch normally providing isolation between the input line and the secondary energy source. Detection of such a failure is accomplished by means of a dummy load which is connected in across the input line. Its impedance is sized to permit a small low level of current flow, above normal leakage current levels permitted by a functioning semiconductor electronic line switch, if energy is reverse coupled from the reserve energy source via a failed electronic line switch without draining significant power from the primary energy source when the UPS is normally operative and deriving power from the primary energy source. A power flow direction sensing circuit detects the direction of power flow at the input to which the primary energy source is connected to the UPS and a control circuit responsive to the power flow direction sensing circuit disconnects the input from the primary energy source if reverse power flow is detected by activating a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.