CONTROL ACCURACY

The time required for the controlled variable to reach and stay within a predetermined band about the control point following any change of the independent variable or operating condition in a control system. Also known as settling time.

1. A series of operations in petroleum refining or natural-gas processing in which the steps are repeated periodically in the same sequence. 2. A periodic change of the controlled variable from one value to another in an automatic control system.

A feedback control in a system with more than one input and more than one output, in which feedback transfer functions are selected so that each input noncontact sensor See proximity sensor.

1. A device which detects the value of the quantity to be controlled by a feedback control system and compares it continuously with the desired value of that quantity. 2. A device used to inspect a gaged part for deviation from a specified dimension, by mechanical, electrical, pneumatic, or optical means.

1. The ratio of the magnitude of the primary feedback signal in a feedback control system to the magnitude of the actuating signal. 2. Total usable power gain of a carrier terminal or two-wire repeater; maximum usable gain is determined by, and may not exceed, the losses in the closed path.

Improvement of the response of a feedback control system by placing a compensator in the feedback path, in contrast to cascade compensation. Also known as parallel compensation.

The analysis of the behavior of the output variable of an automatic control system as the system changes from one steady-state condition to another in terms of such quantities as maximum overshoot, rise time, and response time.

1. An instrument used to measure continuously or at intervals a condition that must be kept within prescribed limits, such as radioactivity at some point in a nuclear reactor, a variable quantity in an automatic process control system, the transmissions in a communication channel or bank, or the position of an aircraft in flight. 2. To use meters or special techniques to measure such a condition. 3. A person who watches a monitor.

In a feedback control loop, the transfer function of the forward path.

Feedback control system in which the relationships between the pertinent measures of the system input and output signals cannot be adequately described by linear means.