Thermal trip arrangements
AssigneeThomas & Betts Corporation
InventorHarry Karmazyn
Life of this patent
Estimating the term…
Abstract
A varistor with no connecting legs extending from it, is mounted in a slot formed in a printed circuit board. The printed circuit board carries the normal circuit tracks. The physical and electrical connection between the printed circuit board and the varistor is achieved by the use of solder. When the varistor overheats to a temperature beyond a predetermined temperature, the solder melts and the varistor is separated from the printed circuit board. A leaf spring which is biased when the varistor is inserted into the slot pushes the varistor out of the slot when the solder melts. Alternatively, when the solder melts gravity causes the varistor to fall out of the printed circuit board.
Claims13
A thermal trip arrangement including a varistor mounted to a printed circuit board characterised in that the varistor comprises a voltage dependent resistor disc sandwiched between a pair of metallic electrically conducting discs and in that the printed circuit board provides mounting means for the varistor comprising an aperture through the printed circuit board for slidingly receiving the varistor with the central axis of its discs generally parallel to the plain of the circuit board, conducting tracks of the circuit board leading to each side of the aperture adjacent the conducting disc of the varistor mounted therein and heat sensitive fixing means providing electrical contact between said discs and tracks, the heat sensitive fixing means being adapted to hold the varistor in the aperture and release the varistor therefrom when the fixing means reach a predetermined temperature, the mounting means including also biasing means for urging the varistor out of the aperture.
Dependencies are inferred from the claim text.