Improvements in or relating to automatic control systems

摘要

868,305. Automatic speed-control systems. DAVEY, PAXMAN & CO. Ltd., and ULTRA ELECTRONICS Ltd. Dec. 23, 1958 [Oct. 11, 1957], No. 31873/57. Class 38 (4). In a control system for a prime mover driving a generator, the fuel supply to the prime mover is controlled by means responsive to the speed and load of the generator so as to maintain the speed constant. A fuel supply valve of a diesel engine driving an alternator is controlled by an actuator 13, Fig. 2. The alternator supplies power to a load through cables 18-20. The voltage and current, from transformers 15-17, is fed to watt-meters 21-23 having a direct voltage output proportional to the real power in each phase. These direct voltages are summated in a circuit 24 and a resultant signal proportional to total power is fed to an amplifier 26 via a resistor 25 for adjusting the constant of proportionality and thereby control the load/speed characteristic of the generator. A direct voltage signal, proportional to the deviation of the speed of the engine from a datum value, is derived from a frequency discriminator 27, connected to cables 19, 20 and is fed to the amplifier via a resistor 28 for adjusting the constant of proportionality. The two direct voltage signals are summated in the amplifier 26 and the amplified direct voltage signal is fed to the actuator 13 in a sense such as to maintain constant the speed of the engine. In a modification, Fig. 3, for load-sharing between similar alternator sets, the outputs of summating circuits 30, 36 are interconnected by a link AA1 and variable resistors 33, 39 are adjusted to control the proportion of the output of the summating circuit associated with each amplifier which is fed into the other amplifier. A link BB1 applies stabilizing feed-back between amplifiers 34, 40.