GB631611A - Improvements relating to regulating apparatus - Google Patents

Abstract

631,611. Automatic regulation. GLYNNE, A. March 14, 1947, No. 7117. [Class 38 (iv)] Regulating apparatus comprises two fourarm bridge circuits, each having in at least one arm of a pair of opposite arms devices 9, 10, e.g. metal filament lamps whose resistance varies with voltage, and in the remaining arms resistors not appreciably changing with temperature, the bridges being transformer coupled to an A.C. supply voltage as shown through inductive and capacitive impedances 20, 19 and 25 respectively so that the third harmonic frequency in the series output of the bridges is eliminated. The output voltage E of each bridge takes the form E=K1(V0-V) sin wt+K2 (cos 3 wt-cos wt) where V sin wt is the actual supply voltage, and V0 sin wt the datum value at which the voltage is to be stabilized, a D.C. voltage with that R.M.S. value being used for initially balancing the bridges. K1 is a constant and K2, being proportional to the supply voltage, approximately constant. By using impedances 20, 19 and 25 with values respectively advancing and retarding the bridge input voltages by 30 degrees the series output of the bridges takes the form with the third harmonic eliminated, which phase variable output may be amplified and used to control the output of a grid controlled mercury arc rectifier. Further, the cos w.t term may be eliminated by an output circuit series resistance 34 with phase quadrature voltage across it developed from a third transformer winding and choke 33, to give an output which may be amplified and added to the supply voltage to correct it. Alternatively, the resistance may be increased to overcorrect the quadrature term and the thus phase advanced output applied to the grids of a mercury arc rectifier as described in Specification 457,814. Specification 559,105 also is referred to.