GB627213A - Improvements in or relating to automatic power factor control - Google Patents

Abstract

627,213. Automatic control of power factor. ORR, J., and TELEGRAPH CONDENSER CO., Ltd. March 26, 1946, No. 4306. [Class 38 (iv)] Automatic power factor control in an A.C. circuit is effected by applying to a fixed capacitor associated with the circuit a voltage which is modified directly by an induction regulator or equivalent device under the control of mechanism directly associated with the circuit wherein control is to be effected. The controlling device may be actuated by means directly sensitive to variation in power factor or reactive K.V.A., or responsive to a quantity such as voltage, current, or power, which is dependent on the power factor. As shown in Fig. 1, the stator windings 4 of an induction regulator are connected across the A.C. mains 1 by leads 6, and the rotor winding 8 is connected in series with a condenser 2 across the same leads. The angular position of the rotor relative to the stator is adjustable in either direction by a reversible motor 15 energized from supplementary mains 16 or from the supply- 1 and provided with alternative terminals 22, 23 connected to contacts 20, 21 respectively which co-operate with a contact 19 on a movable arm 14. The arm 14 is connected by a lead 18 to one supply line 16, the other being connected to motor terminal 17. Movement of the arm 14 is effected in known manner under the simultaneous control of a voltage coil 9 and a current coil 11 fed from a current transformer 13. In a modification, Fig. 3 (not shown), a movable armature 36 arranged similarly to the arm 14 is controlled by a solenoid 34 which is connected across the mains and subjected to variations in the effective mains voltage. A similar arrangement controlled by a current transformer is also described. In a further modification, Fig. 2 (not shown), the induction regulator comprises two series - connected oppositely wound windings 26, 27 spaced on the same limb of a closed magnetic core 28 and connected across a condenser 2. A short-circuited coil 29 located between the windings 26, 27 and movable relative thereto along the core is carried by a block 33 in screw-threaded engagement with a rod 32 which is rotated under the control of mechanism similar to that of an integrating wattmeter and comprising a rotating disc 30 which is responsive to the effect of current and voltage coils as in the other examples. A torque magnifier may be interposed between the shaft carrying the disc 30 and the screw-threaded rod carrying the shortcircuited coil.