GB642535A - Improvement in and relating to voltage regulators - Google Patents

Abstract

642,535. Automatic voltage control systems. TRIGGS, W. W. (Electric Machinery Mfg. Co.). Sept. 6, 1946, No. 26881. [Class 38 (iv)] Apparatus for regulating the voltage output of an A.C. generator 11 comprises a tuned circuit 26, 27 and a rectifier 28 for controlling the exciter 17 for the field of the generator. The voltage from generator 11 is fed through a transformer 31 to the circuit 26, which comprises a tunable inductance 36 and capacity 37 forming a series resonant circuit. Thus, any increase or decrease of the output voltage produces an amplified increase or decrease 'of voltage across the capacity 37. This voltage is rectified by the rectifier 28, the rectified output developed across resistor 79 producing a voltage in a field winding circuit 20 of the exciter 17 which opposes the voltage produced by the exciter 17. Since the exciter supplies the field winding of the generator 11, any variation in A.C. output of the generator from a predetermined value results in an alteration of the voltage across the field winding 13 tending to restore the output to the predetermined value. Initial settings of the inductance 36 may be made by means of a switch 55 and screw 47, whilst the voltage across the capacity 37 may be controlled by a variable resistor 61. In a modification, a stabilizing transformer is connected to the output of the exciter to prevent hunting, Fig. 2 (not shown). In a further modification, Fig. 3 (not shown), an additional field winding may be employed for the exciter and the control voltage impressed on that winding.