GB195086A - Improvements in or relating to means for starting electric motors - Google Patents

Abstract

195,086. Suczek, R., and Sousedik, J. March 17, 1922, [Convention date]. Systems for alternating-current motors only; controllers, actuating.-An automatic starter for an alternating current motor having one or more rotor windings, comprises mutually inductive coils r, r<1> adjacent to a resistance ring o and connected through leads s, s<1> to the terminals of an auxiliary winding, which is thus subject to a high initial impedance and can only accelerate gradually. With increasing speed, the frequency of the current induced in the auxiliary winding and consequently the impedance due to the inductive coils and also the ohmic losses in the resistance ring decrease. At a sufficient speed, pivoted armatures r carrying contact-levers f are moved outwards against magnetic attraction by centrifugal force, and make connection with terminals e so as to close circuits through the main rotor winding, which in the example described, is a three-phase winding. All the parts shown in the Figures are mounted on a cast iron casing a which is carried on the motor shaft b. The casing, the shaft, and the armatures, constitute a magnetic circuit of intentionally high hysteresis, the airgaps in which can be adjusted by screws n. In a madified construction adapted for larger motors with a normal three-phase rotor winding, the centrifugal contacts are attached to longitudinally sliding solenoid cores, and the casing and its attached terminals are more substantially constructed. The invention is stated, in case of due reduction of speed, to exercise an automatic current regulating effect like an overload relay. The current connections of the starter to a motor with a three-phase main winding and a two-phase auxiliary winding are described in the Specification,