GB450278A - Improvements in systems for preventing radio interference by electrically driven apparatus - Google Patents

Abstract

450,278. Protective arrangements. ELECTROLUX, Ltd., Luton-(Assignees of Aktiebolaget Elektrolux; 2, Norrmalmstorg, Stockhohn) May 31, 1935, No. 15887. Convention date, June 3, 1934. [Class 38 (iv)] Relates to apparatus driven by an electric motor and particularly for domestic purposes the motor having an insulated housing and another insulated surrounding casing, and in which for preventing radio interference a condenser circuit is connected between the brushes or field windings and to the motor housing and consists in the provision of a condenser between a point of the condenser circuit and the casing. The motor has an insulated housing 10, Fig. 1 and is attached to an insulated ring to which is mounted an inner casing 24 comprising members 13, 14 and 15 electrically connected together. The ring attaches to an outer metallic casing 17. As shown in Fig. 2, the brushes are bridged by series connected condensers 25 the junction 26 of which is connected to the housing 10 and through a condenser 27 to the inner casing 24. In a modification of this a further condenser is connected between the inner casing 24 and the outer casing 17. In a further modification the condensers 25 are connected to the outsides of the field coils 23. In a further modification the point 26 is connected through condensers to the housing 10 and inner casing 24. The various condensers may be grouped in a common casing. In the form shown in Fig. 3, the condensers 25 are connected to the field coils 23, and condensers 28, 27 and 29 respectively are connected between the casings and to the point 26. In further modifications two circuits are employed, one connected between the brushes, and the other between the field coils.