process and apparatus for the automatic adjustment of the secondary voltage of transformer windings by means of the number of primary winding for variations ifthe voltage of the grid multanées in limi

摘要

988,146. Transformer arrangements. CHIRANA PRAHA NARODNI PODNIK. May 5, 1961 [May 6, 1960], No. 16377/61. Heading H2H. In a system for automatically maintaining a predetermined output voltage from a mains transformer, the number of primary turns is adjusted under the control of means which include a potentiometer supplied with a stabilized direct voltage and having a slider mechanically connected to the transformer tap adjuster, and a second potentiometer, having hyperbolic characteristics or scale and supplied with a direct voltage proportional to the mains voltage, the output voltages from the two potentiometers being maintained equal by automatic adjustment of the first potentiometer. In Fig. 3 a tapping J3 on the primary winding of a mains transformer TR supplying, for example, X-ray apparatus, is adjusted by a reversible electric motor M under the control of a polarized relay PR energized from opposed potentiometers P1, P2. A direct voltage proportional to the mains voltage is applied to potentiometer P1 so that variations are effective to operate motor M which rebalances potentiometer P2 and simultaneously adjusts tapping J3 so that the voltage of the secondary (not shown) of transformer TR is maintained constant at a value determined by the setting of potentiometer P1. The arrangement is such that sensitivity of control is constant over the range of adjustment of potentiometer P1 which may be hyperbolic, have a hyperbolic scale, or be a combination of potentiometers producing the same effect.