BigPatents India

The invention relates to a method and a device (1) for combined current limitation and power breaking and to a switchgear having said device (1). In a combined current limiter/power braker (1) according to the invention, a movable electrode (3, 3') is guided automatically along a resistance element (5) for the current limiting path (31) by an overcurrent-dependent force (Fmag) for the purpose of current limitation and brought to an insulator (8) in a serial arrangement for power breaking purposes. Examples of embodiments are, inter alia, the utilization of Lorenz force for automatic current limitation; movable electrodes (3, 3') realized by means of liquid metal (3) or a movable solid conductor (3'); an electrical resistance (RX) increasing non-linearly in the direction of movement (x) for smooth power limitation characteristics and a resistance element (5) in the form of a dielectric matrix (5) with several channels (3a) for the liquid metal (3). Amongst the advantages achieved are electric arc-free, reversible current limitation and power breaking, which is also suitable for high voltages and currents, rapid reaction times, little wear and easy maintenance.