GB613096A - Improvements in and relating to voltage regulating systems - Google Patents

Abstract

613,096. Automatic regulation WINTHER, M. P. Jan. 30, 1946, No. 28997. Convention date, May 4, 1944. Divided out of 613,052. [Class 38 (iv)] A voltage regulating system is arranged to produce in the secondary winding of a transformer an output voltage which has a substantially straight line characteristic and is proportional to the current in a polyphase circuit supplying an A.C. motor under variable load. As shown, a 3-phase motor W.M. is connected to lines L1-L3, which have the primary winding of a current transformer T11 connected across lines L1-L2. A resistance R13 connected across the secondary winding of transformer T11 has a variable tapping 33 connected to one end of the secondary of transformer T10, the other end being connected to one end of the primary winding of an output transformer T9, which is shunted across a resistance R12 with a tapping 32. Resistances R12, R13, have a common junction joined to one end 34 of the secondary of transformer F11. The tapping 33 on the resistance R13 is adjusted until the voltage derived from transformer T11 cancels that derived from T10 when'the motor is idling, i.e. it bucks down the component of the current produced in T10 by the magnetisation current of the motor. The subsequent load-ampere characteristic of the motor is substantially a straight line, and a straight line relationship is obtained between the secondary Voltage of transformer T9 and the torque of motor W.M. The slope of the line can be changed by adjustment of tapping 32 on potentiometer R12.