Use of capacitance for protecting against overheating of a waterbed heater
US4994750A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1989 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | Jul 14, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H5/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A protection device for a waterbed protects the water bladder and water heater from damage due to overheating when a dangerous condition, such as an insufficient level of water within the bladder or an element of the waterbed surroundings interposed between the bladder and the water heater, arises. The protection device employs a detector in the form of two capacitance plates placed adjacent to the water bladder and connected to a circuit which is operative to prevent power from being supplied to the water heater upon detection of a dangerous condition. The capacitance of the detector plates varies with the level of the water within the bladder and with the presence of a surrounding element between the bladder and heater.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.