Electric protection device
US4392174A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 1982 |
| Grant date | Jul 5, 1983 |
| Priority date | — |
| Expiry date | Jun 11, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/331
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A protection device has first and second differential transformers each with a toroidal magnetic core through which pass the neutral and phase conductors of an alternating current distribution network, and a secondary winding. The secondary winding of the first transformer is coupled to the input of an amplifier followed by a rectifier, a threshold comparator and a control device adapted to release a circuit-breaker. The secondary winding of the second transformer is coupled to the output of the amplifier. The improvement is constituted by an auxiliary amplifier inserted between the output of the first amplifier and the terminals of the secondary winding of the second differential transformer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.