Temperature limited heaters with relatively constant current
US7481274B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 2005 |
| Grant date | Jan 27, 2009 |
| Priority date | — |
| Expiry date | Jun 19, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B3/141
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Certain embodiments provide a system configured to heat a subsurface formation. The system includes an electrical power supply. A heater section includes one or more electrical conductors electrically coupled to the electrical power supply. At least one of the electrical conductors includes ferromagnetic material. The heater section provides a first heat output when time-varying electrical current is applied to the heater section below a selected temperature, and a second heat output approximately at and above the selected temperature during use. The second heat output is reduced compared to the first heat output. The system is configured to allow heat to transfer from the heater section to a part of the formation. The electrical power supply is configured to provide a relatively constant amount of time-varying electrical current that remains within about 15% of a selected constant current value when a load of the electrical conductors changes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.