Spark elimination circuit for controlling relay contacts
US6768615B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Jun 24, 2002 |
| Grant date | Jul 27, 2004 |
| Priority date | — |
| Expiry date | Sep 11, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2009/566
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A relay control circuit is connected between a power source supplying an alternate current and a load to which the alternate current is supplied. The relay control circuit includes contacts for conducting/cutting off the alternate current supplied from the power source to the load. A first zero-crossing detection circuit is connected to the power source and generating a first zero-crossing signal to a control unit having a memory unit storing a time delay parameter. The control unit issues a control signal to energize a coil for actuating the contacts at a time point that leads the zero crossing point of the alternate current a time period equal to the time delay parameter whereby the contacts are actually actuated at a time point corresponding to the zero-crossing point. A second zero-crossing detection circuit is coupled to the load and generates a second zero-crossing signal. In case of deterioration of the performance of the relay, a difference exists between the time of detection of the second zero-crossing signal and the time point of the time delay parameter after the control signal. The difference is used to correct the time delay parameter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.