Radiant electric heaters
US5043559A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 2, 1990 |
| Grant date | Aug 27, 1991 |
| Priority date | — |
| Expiry date | Nov 2, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B2213/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A radiant electric heater (10) has two coiled resistance wire heating elements (22,24) each connected to one terminal (N) of a power supply via respective rectifiers. These rectifiers are each made up of two like-poled arms of a bridge rectifier (34) connected in parallel, and they are arranged to allow current through one heating element (22) on positive-going half-cycles of the power supply waveform, and through the other heating element (24) on negative-going half-cycles. The elements are rated for continuous power dissipation under these circumstances. A PTC thermistor (36) is connected between the ends of the heating elements connected to the rectifiers. Optionally an NTC thermistor (40) can be connected in series with the PTC thermistor. Upon initial energization the PTC thermistor is a near short-circuit, so current flows through both heating elements on both polarity half-cycles, dissipating twice their rated power. The elements increase in temperature more quickly than if they were initially energized at only their rated power, so the visible response of the elements to energization is faster. Meanwhile the PTC thermistor increases in resistance owing to self-heating, ther…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.