Patent GB-591311-A (GB)
Title: Improvements in and relating to electrical regulating systems
IPC: H02P9/22
Filed: 1945-01-03
Abstract: 591,311. Automatic control systems. PEARSON, S. O. Jan. 3, 1945, Nos. 303 and 4305. [Class 38 (iv)] In a device for automatic voltage stabilization of A.C. or D.C. generators or for automatic speed regulation of D.C. motors or for other analogous purposes, a vibrating contact relay or a carbon-pile or a carbon-silver-pile resistance is controlled by a coil in a known manner with a thermionic amplifier, interposed between the coil and the factor to be stabilized. In one embodiment, Fig. 1, the voltage between bus-bars 65, supplied by generator 58, is controlled by the action of vibrating relay 63, 64 on the field 62 of exciter 60 which supplies the exciting current to the field 59 of generator 58. The anode current of thermionic valve 66 passes through relay operating coil 64'and is controlled by grid 68 which is connected to the positive bus-bar, the cathode being taken to the negative bus-bar. A rise in the output voltage of 58 causes an increase in the current through valve 66, and consequently through coil 64, to open contacts 63. Resistor 61 is thereby inserted into the shunt field circuit of exciter 60 to cause a reduction of its output voltage and a lowering of the generated E.M.F. of 58. In a second embodiment, Fig. 2, voltage control of generator 71 is achieved by the connection of a carbon-pile or carbon-silver-pile resistor 72, in series with the field 73. The compressive force on the pile is varied by means of the arm 74, coil 75 and thermionic amplifier 76, to produce corresponding changes in its resistance which are such as to cause a correction in the induced armature, E.M.F. for any alteration in the bus-bar voltage from a datum level fixed by potentiometer 84. A rise in bus-bar voltage with the resultant increase in negative potential of the grid 77 causes a fall of current through anode 79, a lowering of the compressive force on pile 72 and a correcting fall of induced voltage. A fall of bus-bar voltage is corrected by a similar sequence of operations initiated by an increase in the current through the thermionic valve. Hunting is countered by the condenser 80 which tends to damp rapid oscillations of the pile 72, the degree of damping depending on the product of the capacitance of 80 and the resistance of resistor 82. In a third embodiment, Fig. 3 (not shown), the output voltage of the associated exciter generator through a vibrating contact relay the operating coil of which is supplied by a thermionic amplifier from alternator bus-bars. In Fig. 4 (not shown), speed control of a D.C. motor is affected by the influence .of a negative booster on the shunt field of the motor, the booster output being subject to the control of a vibrating contact relay, the operating coil of which is supplied by a thermionic amplifier, the input to which is taken from a magneto generator driven by the motor. In a further embodiment, Figs. 5 and 6 (not shown), speed control of a shaft is accomplished by the control of the excitation of an eddy-current clutch of the slipping type..The controlled shaft is driven through a clutch from a prime mover and has coupled to it a magneto-generator. The output voltage of the latter is amplified by thermionic means and controls a vibrating contact relay which influences the output of a generator supplying the excitation to the clutch. Specifications 591,309 and 591,310 are referred to.