GB693404A - Improvements in or relating to systems for energizing electrical precipitators - Google Patents

Abstract

693,404. A.C. motors. RESEARCH CORPORATION. May 28, 1951 [June 14, 1950], No. 12459/51. Class 35. A squirrel-cage motor for driving a rotary rectifying switch for electrostatic precipitators is rendered synchronous by means of permanent magnets on the squirrel cage member. In one form, Fig. 2, the squirrel cage rotor 31 has longitudinal salient poles 56, 57, 58, 59 on its periphery, each of these poles carrying permanent magnets 49, 52. In an alternative form, the rotor is wound and the squirrel cage stator carries the salient poles and permanent magnets. In a modification, Fig. 3, the squirrel cage rotor carries polepieces 56, 57, 58, 59 without permanent magnets, the correctlyphased synchronization being ensured by a permanent magnet rotor 60 influenced by the same stator. In a further modification separate stators with separate windings are used for the squirrel cage and permanently magnetized rotors. Alternatively either or both of the squirrel cage or permanent magnet members may be stationary while the armature windings rotate. Circuits are described for energizing the squirrel-cage section independently of the permanently magnetized section which may be connected to the supply manually or automatically after a time interval, in response to a predetermined voltage generated by the permanent magnet section, or by a centrifugal switch. The permanent magnet section may be de-energized when the motor is synchronized.