GB495973A - Thermostat with dry contacts - Google Patents

Abstract

495,973. Thermal switches. ELECTROAPPAREILLAGE. May 28, 1937, No. 14916. Convention date, May 28, 1936. [Class 38 (v)] Relative expansion of a tube b and rod c with change of temperature lowers a block d and brings two inclined bosses h<1>, h<2> into engagement with a ball or cone i, the bosses being thereby forced apart, together with the strips e<1>, e<2> that carry the bosses and the contacts f <1>, f<2> on the strips. The strips el, e<2> carry co-operating magnets g<1>, g<2> to produce a quick " make " and "break." The temperature of operation may be adjusted by varying the position of the ball i. This rests on a rod j, the two ends of which respectively rest on a fixed and an adjustable support. As an additional precaution, the above device may be combined with a fusible device operating on excessive rise of temperature. In the form shown, a conical or like fusible block m normally holds up a spring n carrying a rod o. When the block m begins to melt it is forced out of its seating and a hook p engages a projection q to move the contact spring e<1> into the open position. In a modification, Figs. 5-8 (not shown), melting of the block m opens contacts in series with the contacts f<1>, , f<2>. In modifications, Figs. 3 and 4 (not shown), only one strip f<1> ,f<2>is movable.