Changeover switching device for paralleling capacitors and, specifically, the start and und run capacitors of rotating-field asynchronous motors with single-phase power supply and intermittent duty cycle

摘要

A changeover switching device which effects the connection of a capacitor in parallel with another one (or more) already charged capacitor(s) and, subsequently, its disconnection and discharge onto a suitable resistor, avoiding the heavy charging and discharging impulse currents which usually damage such changeover switches.;It includes a choke coil (4), and exists in two versions: (a) an electromechanical version with a changeover switch (5) and a timing circuit (1); (b) an electronic version with a changeover switch (5) and a timing circuit (1, 6, 7, 8).;The figure shows its principal application in rotating-field asynchronous single-phase or three-phase motors, with single-phase supply (10), and having one or two main windings (11) and one auxiliary winding (12); to the auxiliary winding, a run capacitor (9) is permanently connected. The device of the invention changes over the start capacitor (2) from the parallel with the run capacitor (9) onto the discharge resistor (3) and viceversa. It is particularly suitable for fast intermittent duty cycles.