GB821674A - Improvements in and relating to cooling system control - Google Patents

Abstract

821,674. Electric measuring systems. BRITISH THOMSON-HOUSTON CO. Ltd. April 2, 1958 [April 2, 1957], No. 10750/57. Drawings to Specification. Class 40 (1). An indication of the effectiveness of a cooling system is obtained by placing two thermistors in heat transfer relationship with the flow of cooling medium, the thermistors being connected in two arms of a bridge circuit which is arranged to supply a predetermined output, preferably zero, when the cooling operation is normal. As described, one thermistor is placed in contact with the wall of a section of a pipe in the cooling circuit at a point beyond the cooled object, such section being insulated from the rest of the pipe, as by gaskets of heat-insulating material, or by making the rest of the pipe of insulating material, and the second thermistor is in contact with the reservoir containing the cooling medium. Alternatively, both thermistors may be positioned close to, but insulated from, one another, the thermistors having different thermal time constants, or the pipe sections in which they are located having different thermal capacities, so that, on a change of temperature of the cooling medium, the temperature of one thermistor will alter more quickly than the temperature of the other.