Method and apparatus for limiting current surge upon transfer of a load between A.C. power sources
US5784240A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 20, 1996 |
| Grant date | Jul 21, 1998 |
| Priority date | — |
| Expiry date | Dec 20, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2300/018
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of and apparatus for actuating an automatic transfer switch for disconnecting a motor load from a normal source of voltage and reconnecting the load to an alternate source of voltage at a time when phase differences between the output voltage of the disconnected motor load and of the alternate source voltage are minimized to prevent excessive in-rush currents to the motor upon reconnection. Actuation of the transfer switch is commenced when the difference in phase between the normal source and alternate source is equal to a predetermined number of degrees depending upon whether the alternate source frequency is greater or less than the normal source frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.