Patent GB-1008359-A (GB)
Title: A control relay embodying a hall effect device
IPC: G05D23/13
Filed: 1962-04-04
Abstract: 1,008,359. Protective systems. Y. NIEDA. April 4, 1962 [Nov. 11, 1961], No. 12872/62. Heading H2K. [Also in Divisions G1, G3 and H1] A relay comprises a Hall plate mechanically coupled to a coil in the magnetic field so that it can be rotated by passing current through the coil. Fig. 1 shows a shaft 7 carrying two Hall plates 1 and 19, the supply current for these plates being supplied via sections of the shaft and electrodes 2, 3 and 20, 21 respectively. Magnets 14, 15 and 30, 31 separated by magnetic screen 18 provide magnetic fields for the two plates 1 and 9. The Hall output from side electrodes 4 and 5 of plate 1 is supplied to coil 6 surrounding the plate thereby tending to rotate the shaft and both plates 1 and 19 due to action of the magnetic field. The Hall output from -electrodes 22 and 23 of plate 19 is supplied to output leads 24 1 , 24 2 . The two plates are initially at right angles to each other and springs 10 and 26 are set to maintain plate 1 normal to its magnetic field and thus operative to provide maximum Hall voltage. Consequently plate 19 extends along its own magnetic field so that its Hall output is zero. If signals are fed into coils 16 and 17 to vary the magnetic field surrounding plate 1, its Hall output changes resulting in the change of current in coil 6 so that plates 1 and 19 rotate and plate 19 also provides a Hall output to terminals 24 1 , 24 2 . In a modification only one Hall plate and associated magnetic field is provided, the one Hall output then being used to provide current for the rotating coil 6 and the output terminals. In a further modification (Fig. 9, not shown) the coil 6 is connected in parallel with the supply electrodes of the Hall plate instead of being connected to the Hall electrodes. The semiconductor plates may consist of files deposited on a glass or plastic cylindrical body containing an iron core or magnet and additional high permeability elements may be provided to increase the magnetic field through the plate. The semi-conductor may consist of germanium, indium arsenide or indium antimonide. A plurality of plates may be provided, some being used to provide the current for coil 6 and some the output voltage. The plate 19 may be set at a predetermined angle relative to plate 1 so that the output from 19 is zero for a particular value of input conditions to plate 1; the operating delay time may be adjusted by varying the tension of springs 10 and 26 and in other ways. The coils 16 and 17 associated with magnets 14 and 15 may be fed separately with two currents in opposition so that if the currents are equal there is no magnetic field through the Hall plate thus providing a differential relay. Several applications of the relay are described involving both D.C. and A.C. inputs and outputs. Fig. 4 shows an arrangement for protecting power lines in which transformers 79 and 80 on opposite sides of generator 81 are connected in opposition across coils 16 and 17 of the magnets for the Hall device relay A. If unbalance occurs the relay provides an output which operates circuit breakers 83 and 84. Reference is also made to an application in which the output is applied to a transistor amplifier used to control a switch to protect a power line.