GB587807A - Improvements in or relating to heat sensitive devices - Google Patents

Abstract

587,807. Temperature-responsive actuating- elements. BROOKHIRST SWITCHGEAR, Ltd., and HUMPHREYS, M. N. Jan. 13, 1945, No. 1081. [Class 64 (ii)] [Also in Group XXXVII] A heat sensitive device comprises a plurality of bimetal strips 10, 11, 12, supported for pivotal movement about the V elements 16 and 17, the strips being connected together at one end by the bar 20 which pivots about the point 21, at the other end the strips normally contacting a stop 23, Fig. 3, and below this end of each strip is a common trip bar 24. Near each strip is its individual heater 13 located in a trough 14 of porcelain or other insulating material. In the case of a thermal overload, the strips raise the bar 20 to operate a trip switch 25 through an operating member 26, or if one of the heating circuits should fail, the movement of the other strips carries the coupled end of the unheated one up,'and so depresses its farther end to move the trip bar 24 and so actuate the switch through the member 27. An unheated bimetal strip 23 may be used to compensate for ambient temperature variation, by varying the position of one of the switch contacts. In a modification, bimetal helices may replace the strips, or strips with linear thermal response characteristics may be used. The device may be employed in a polyphase alternating current electric circuit.