Automatic transfer switch
US4021678A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 19, 1976 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Jan 19, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2300/018
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An automatic transfer switch having two sets of phase switches, one set for connection between a normal power source and a load and the other set for connection between an emergency power source and the load. The transfer switch also includes two neutral switches, one for connection between the normal source neutral and the load neutral, and the other for connection between the emergency source neutral and the load neutral. Only one set of the phase switches can be closed at any one time, and during transfer of the load from one source to the other both sets of phase switches are open. Prior to a transfer operation, the neutral switch corresponding to the closed set of phase switches is closed and the neutral switch corresponding to the open set of phase switches is open. During transfer of the load, both neutral switches are closed before the closed set of phase switches open and both neutral switches remain closed until after the closed set of phase switches open and the open set of phase switches close. Thereafter, the neutral switch which had originally been open remains closed and the neutral switch which had originally been closed opens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.