Variable high-current resistor, especially for use as protective element in power switching applications & circuit making use of high-current resistor

摘要

PCT No. PCT/DE93/00721 Sec. 371 Date Feb. 14, 1995 Sec. 102(e) Date Feb. 14, 1995 PCT Filed Aug. 11, 1993 PCT Pub. No. WO94/06130 PCT Pub. Date Mar. 17, 1994A variable high-current resistor, especially for use as a protective element in power switching technology has already been proposed, which contains carbon as a resistance material, at least one boundary layer with a transition zone to another electric conductor being provided. By applying a contact pressure, the resistance in the transition zone can be kept low. Under the prior art, the resistance is converted into a highly resistive state by means of Joulean heat. In accordance with the invention, the contact pressure of the variable high-current resistor is able to be selectively influenced, the carbon- and/or carbon-black-containing layer being pressed by the surface pressure with a preset first value against the other conductor to adjust the low-resistance state of the resistor, and that, in the event of a short-circuit, this contact pressure being able to be reduced in a short enough time to a second value, at which the resistance in the transition zone goes up by at least two orders of magnitude. High-current resistors of this type are able to be used in conjunction with circuit-breakers, power semiconductors, contactors and vacuum contactors.