Double DC coil timing circuit
US5168418A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1991 |
| Grant date | Dec 1, 1992 |
| Priority date | — |
| Expiry date | Apr 19, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H47/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Control circuitry is disclosed for electrical starters, contactors and the like having a starting winding and a serially coupled holding winding wherein the holding winding is shorted until the separable main contacts have closed which includes circuitry which obviates the need for relatively precise sensing of the position of the separable main contacts to control the holding winding. In one embodiment of the invention, the unshorting of the holding winding is delayed a predetermined number of cycles after the separable main contacts have closed to avoid the necessity of relatively accurate mechanical sensing of the position of the separable main contacts. In this embodiment a relatively less expensive field effect transistor or the like is used to short out the holding winding until the separable main contacts have closed. This allows the use of a relatively less expensive limit switch with a substantially smaller DC capability. In alternate embodiments of the invention, control circuits are provided which allow the limit switch normally used for sensing the position of the separable main contacts, to be eliminated altogether, thus further reducing the cost of the device as well …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.