Patent GB-745983-A (GB)
Title: Improvements in or relating to a process and apparatus for heating water by electrical conduction
IPC: F24H1/10
Filed: 1954-02-11
Abstract: 745,983. Thermal switches. INDEVCO, Inc. Feb. 11, 1954 [April 27, 1953], No. 4027/54. Class 38(5) [Also in Group XI] In heating water by passage current therethrough between one electrode 18 at one potential and a plurality of electrodes 22 insulated from each other and operating at the same potential said potential being different from that of the first electrode, the electrodes 22 are energized simultaneously and the current supply thereto is interrupted under thermostatic control by opening a plurality of switches each of which is connected to one of these electrodes 22 and mechanically interconnected with each of the other switches. The electrodes 22 are energized at a common poten-. tial through parallel circuits, to which the flow of current is interrupted substantially simultaneously by a thermostat 41 immersed in the cutgoing hot water. The electrode 18 comprises a conical carbon block carrying axially'a steel shaft 10 hollowed out. at both ends. The electrodes 22 are segmental and arc-shaped in cross-section and are mounted with their inner surfaces parallel to and spaced from the electrode 18 by insulating discs 30, 31 on the shaft 1.0. The discs carry an outer hollow, conical carbon electrode 27 and a metal casing 46. Water entering a nipple 38 passes through holes 14 in, the hollow end of the shaft 10 and passes over the electrodes to enter apertures 17 in the hollow end of the shaft 10. The hot water passes over thermostat 41 mounted in the hollow shaft 10 to an outlet nipple 39. The thermostat comprises a bimetallic 'helix 49 secured at one end to a base 48 and at the other end to an axial shaft 50 extending through the end mounting and through a central aperture of a'metal disc 47. An insulating arm 58 secured at one end to the shaft 50 carries at the other end an adjusting screw 64. adapted to bear on a pin 65 on the disc 47 when the shaft 50 rotates on rise of temperature of the water passing over the thermostat. The plate 47 has upwardly bent lugs 55 equal in number to the number of electrodes 22, each lug carrying a contact disc 66. On the outer face of end disc 31 are mounted by pins 62 L- shaped metalbrackets 69d equal in number to the number of electrodes 22. Each pin 68 passes through the disc 31 to make electric contact with an electrode 22. A springy arm 70 mounted at 72 on each bracket 69a carries a contact disc 71 adapted to engage a cental 66 when the thermostat is cold. When the water is sufficiently heated, the shaft 50 of the thermostat rotates and the screw 64 on the arm 58 bears on the pin 65 to rotate the disc 47 and thereby carry the contact discs 66 away from the contact disc 71. When the apparatus cools the screw 64 moves away from the pin 65 and the disc 47 is rotated by a pin 60 moved in a slot 61 in the disc 47 by a helical spring 62. Current is supplied to the inner electrode 18 by pin 75 connected through the metal nipple 38 to the shaft 10, to the outer electrode 27 by a ring 76 through the metal casing 46 and to the plate 47 by a flexible wire 77. With a D.C. or 2 phase A.C. supply the electrodes 18 and 27 are earthed and electrodes 22 are energized. With a-3 phase A.C. supply, the pin 75, ring 76 and wire 77 are connected one to each phase, and opening of the switches on the plate 47 does not interrupt current to the inner and outer electrodes. By small variations in the spacing of the brackets 69a, switches on the plate 47 may be made to open seriatim.