( 2 of 2 ) |
United States Patent | 7,643,262 |
Titschert , et al. | January 5, 2010 |
A protection circuit for intrinsically safe electromagnetic actuators operating on the voltage from a power unit (1) approved for underground mining, for switching electrohydraulic valves (5) in underground mining, comprising at least two spaced-apart short-circuit means (14, 16 or 16A) connected in parallel with the electromagnetic actuator coil (11) for short-circuiting the coil in the event of a reversal of the coil voltage. According to the invention, at least one of the short-circuit means comprises a short-circuit semi-conductor switch (16 or 16A) and a voltage-reversal detecting circuit (30) for activating the short-circuit semiconductor switch (16).
Inventors: | Titschert; Jens (Lunen, DE), Lenzing; Markus (Selm, DE), Travis; Jeff (Fairmont, WV), Ferguson; Dan (McKees Rocks, PA) |
Assignee: |
DBT GmbH
(Lunen,
DE)
|
Appl. No.: | 11/334,607 |
Filed: | January 18, 2006 |
Jan 19, 2005 [DE] | 10 2005 002 648 | |||
Current U.S. Class: | 361/91.1 ; 361/111; 361/56 |
Current International Class: | H02H 3/20 (20060101) |
Field of Search: | 361/93.1,56,91.1,111 |
4178619 | December 1979 | Seiler et al. |
4551643 | November 1985 | Russell et al. |
4665459 | May 1987 | Bynum et al. |
4740202 | April 1988 | Stacey et al. |
5381297 | January 1995 | Weber |
5806522 | September 1998 | Katims |
6137192 | October 2000 | Staffiere |
2001/0026431 | October 2001 | Mechanic |
2003/0160200 | August 2003 | Suilmann et al. |
63003689 | Jan., 1988 | JP | |||