Switching circuit having delay for inrush current protection
US8278839B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 2010 |
| Grant date | Oct 2, 2012 |
| Priority date | — |
| Expiry date | Nov 29, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H9/547
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A two-wire switching circuit can handle a large inrush current, but does not require a neutral connection or a heavy-duty mechanical switch or relay. The switching circuit comprises a mechanical air-gap switch, a first controllably conductive device (e.g., a bidirectional semiconductor switch), and a second controllably conductive device (e.g., a latching relay), which are all adapted to be coupled between an AC power source and an electrical load when the air-gap switch is in a first position. First and second delay circuits control the semiconductor switch and the latching relay to be conductive at different times after the air-gap switch is changed to the first position. Specifically, the semiconductor switch is rendered conductive before the latching relay is rendered conductive, such that the semiconductor switch conducts the large inrush current. The latching relay conducts current from the AC power source to the electrical load after the inrush current has subsided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.