GB439166A - Improvements relating to electric regulating systems - Google Patents

Abstract

439,166. Converting ; automatio regulation. BRITISH THOMSON -HOUSTON CO., Ltd., Crown House, Aldwych, London, and KINMAN, T. H., Ladbroke House, Bilton Road, Rugby. March 2, 1934, No. 6737. [Classes 38 (ii)] In an arrangement for maintaining constant, under varying load circuit conditions, the output of a high frequency oscillation generator V2 feeding a load such as an induction furnace winding L4, the oscillation generator is supplied by a grid-controlled rectifier V1, and a voltage derived by rectifying a part of the output of the oscillation generator is caused to control the conductivity of a triode V4 which in turn controls the phase of the potential applied to the grid of the rectifier V1. The grid of the triode V4 is normally negatively biassed by the drop across a discharge tube N3 connected in series with other discharge tubes N1, N2 from which the anode circuit is energized, the three discharge tubes being supplied from an auxiliary rectifier V3. When the triode V4 is non-conductive, the full anode voltage thereof is effective to energize through a discharge tube NL a saturating winding Ls associated with the inductance T3 of a phase shifting bridge in the grid circuit of the rectifier V1. Under these conditions the rectifier operates at the upper limit of output voltage. A part of the output of the oscillation generator V2 is supplied through a condenser C3 to an auxiliary rectifier V5 associated with a resistance P, and the drop across the latter which is proportional to the output is used to effect regulation by neutralizing the fixed bias on the grid of the triode V4. When the latter is thus rendered conductive, the voltage applied to the tube NL is reduced by reason of increased drop in the anode resistance P1 ; the discharge at the tube NL ceases, and the resulting increase in the value of the inductance T3 reduces the output voltage of the rectifier to a lower limit. The level at which the output of the oscillation generator is maintained may be varied by manual adjustment of the condenser C3 or of the resistance P.