GB513059A - Improvements relating to automatic starters for electric motors - Google Patents

Abstract

513,059. Electrically - released switches. DONOVAN ELECTRICAL CO., Ltd., and DONOVAN G. O. March 16, 1938, No. 8085. [Class 38 (v)] The electromagnet 3 controlling the main contacts 3a and a retaining contact 4a of an automatic starter for a motor is energized by depressing a button g to close contacts g', g<2>. A further button h, acting through a lever h', can move a slidable bar c to the left and move a contact-carrying lever d clear of a contact f to de-energize the electromagnet 3. Each line contains an overload relay b having an actuating and resetting arm b<1> engaging in a notch c<1> in the bar c, whereby on overload the bar is moved to the right to move contact-lever d away from a contact e. In order to reset the arm b<1>, the button h is depressed beyond its normal stopping position, or alternatively a separate resetting button is provided. The relays, Fig. 3, each comprise a central pin b<3> secured to a tube b by solder b<5> and carrying a ratchet wheel b<4>. The arm b' is freely movable on b<3> but is normally held by a pawl b<6> engaging the ratchet b<4>. When the solder b<@5> is melted by the current in the coil b<2>, the spring b<7>rotates the arm b' to the contact opening position.