Some aspects of process control instrumentation

This paper discusses some of the instrumentation aspects of process control. It considers the electrical methods of measuring temperature and includes a description of the low-level d.c. amplifiers used in connection with thermo-couple measurements based on the contact modulator, galvanometer-photocell and galvanometer-oscillator methods. The application of vane controlled r.f. oscillators to direct-current telemetering systems and electrical force balance measurements are also described and discussed.