Residual current device having voltage dependent and voltage independent modes of operation
US8446699B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 11, 2007 |
| Grant date | May 21, 2013 |
| Priority date | — |
| Expiry date | Oct 6, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H1/063
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
This invention relates to a residual current device which is able to safely and reliably operate when a line voltage is present (voltage dependent mode) and when the line voltage is not present or falls below a predetermined threshold level (voltage independent mode). The present invention is implemented as a residual current device having a trip mechanism for isolating an electric supply to an electrical installation upon detection of a predetermined current imbalance between the line and neutral conductors of said electric supply. The present invention comprises a current transformer having a secondary winding responsive to any current imbalance on said electrical installation, and a circuit protection winding being connectable to a processing means. The impedance of said processing means varies according to the level of the line voltage such that the device, under normal operation, behaves as a voltage dependent residual current device, but in the rare occasion where operation may be required when no line voltage is present, offers voltage independent protection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.