GB1297445A - - Google Patents

Abstract

1297445 Electromagnetically and thermally tripped switches ELLENBERGER & POENSGENGmbH 30 Oct 1970 [4 Nov 1969] 51805/70 Heading H1N An overload switch includes a magnetic circuit arrangement including two sets of substantially parallel limbs 49, means, such as a permanent magnet 44, to premagnetize the limbs and a magnet armature 55 associated with each set of limbs with the armatures connected to a lever 54 associated with a movable contact carrier 11 which retains its contact 12 in engagement with a fixed contact 13 when the armatures 55 are held to the ends of the limbs 49 by the premagnetization and is caused to move its contact away from the fixed contact when one armature is moved away from its respective limbs 49 due to the bias of a spring 65 when flux in the associated limbs is reduced due to current in the coils 56 exceeding a predetermined value. The coils are wound such that the flux produced thereby is in the same direction as the polarizing flux in one set of limbs 49 and opposes the polarizing flux in the other set. The normal current in the coils is just below the saturation level of the limbs so that the added flux in one set of limbs, when the current increases to a value above the predetermined level, does not increase the attractive force to any great extent and the tilting of the lever 54 under the action of the spring 65 is sufficient to move both armatures 55 downward. The attractive polarizing force can be varied by rotation of a shunt 47 engaged by the upper ends of the limbs. The slide 32 on which the lever 54 is mounted has a pin 30 projecting into a slot 31 in a pivoted lever 27 which has an L-shaped slot 28 which receives a pivot pin 24 of a contact carrier 11. The pin 24 is constrained to move in a slot 25 in a frame member 9. A push-button assembly 6 biased by a spring 10 is arranged, when depressed, to move the contact carrier 11 forward whilst a pin 38 on the carrier 1 engages a cam surface 39 on the lever 7 to move the lever and slide inward, so as to move the armatures 55 to the held position and bring the pin 24 into the part 29 of the L-shaped slot 28 in the lever 7 where it is held latched so that the spring 34 rotates the carrier 11 about the pin 24 into the contact closed position. When the armatures are released as explained above, the lever 7 is rotated to release the pin 24 from the slot part 29 and the spring 34 opens the contacts.