VARIABLE SETPOINT PROPORTIONAL CONTROL APPARATUS FOR VACUUM BAKEOUT SYSTEMS

摘要

An electronic heater control system for maintaining the vapor pressure within a vacuum bakeout system at an optimum level by causing the heating elements to be alternately energized and de-energized at a high frequency with the ON-OFF duty cycle being determined by the instantaneous vapor pressure in the system. The control circuitry includes a means for generating a time varying reference signal and a signal comparator means for comparing a pressure responsive signal to the reference signal. The comparator means then generates a heater control signal in response to the comparison for use in driving a heater energization switching means.