ABSTRACT
Set the integral and derivative constants to a minimum so that the proportional band may be adjusted first. The proportional band should be set as tightly as possible so long as there is no indication of on-off oscillation. The derivative function should then be increased, which should act to minimize overshoot/undershoot during a sharp change in thermal schedule or on initial startup. Increasing the derivative constant too much
will cause a jagged oscillatory behavior. The derivative function, as a general rule, should not dominate the overall control instruction. Increasing the integral constant should eliminate parallel ramping more rapidly. Over-emphasizing this function will cause "integral windup", where the accumulation of area has so much momentum that it causes the furnace temperature to adopt broad oscillations about the setpoint with continuously increasing amplitude.
