GB892953A - Indicating and/or control apparatus - Google Patents

Abstract

892,953. Electric correspondence control systems. BAILEY METER CO. April 16, 1958 [April 17, 1957], No. 12168/58. Class 40 (1). In an indicating or control system for an industrial plant, an electric signal proportional to a variable dependent on operation of the plant is modified by a non-linear mechanism involving movement, to provide a variable electric reference signal which is compared with an electric signal proportional to a variable, which changes under influences external to the plant and which influences the plant, to produce an error signal for indication or control. In Fig. 1 a direct voltage corresponding to the electrical power supplied by a turbo-generator 4 is derived from a thermal converter 7 of the thermocouple type and applied to a follow-up servomotor 16 which thus adjusts a shaft 17 to a position corresponding to the generator power output. Shaft 17 operates an indicator 21 and controls a movable core transformer 27 through a cam 22 which is so shaped that the signal developed across a potentiometer 32 corresponds to a desired temperature of boiler feedwater corresponding to the particular generator power output. The actual feedwater temperature is measured by a resistance thermometer or thermocouple 9 which controls a movable core transformer 31. The signals corresponding to actual and desired feedwater temperatures are applied, differentially, to control a motor 40 which, in balancing potentiometer 32, indicates any difference and thereby operates a fluid pressure control valve 33 to control the temperature of the feedwater through a system not described. Further signal generators 28, 29 operated by cams 23, 24 on shaft 17 may respectively control the heat supply to and the vacuum associated with the generating unit. Constructional details of the assembly and rack-mounting of the servomotors, cams and signal generators are described.