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Direct digital control is the automated control of a condition or process by a digital device (computer). [ 1 ] [ 2 ] Direct digital control takes a centralized network-oriented approach. All instrumentation is gathered by various analog and digital converters which use the network to transport these signals to the central controller.
Some semiconductor devices are diode junction-based and are nominally rectifiers; however, the reverse-breakdown mode may be at a very low voltage, with a moderate reverse bias voltage causing immediate degradation and vastly accelerated failure. 5 V is a maximum reverse-bias voltage for typical LEDs, with some types having lower figures.
The system is called reverse acting if it is necessary to apply negative corrective action. For instance, if the valve in the flow loop was 100–0% valve opening for 0–100% control output – meaning that the controller action has to be reversed. Some process control schemes and final control elements require this reverse action.
Departure of such a variable from its setpoint is one basis for error-controlled regulation using negative feedback for automatic control. [3] A setpoint can be any physical quantity or parameter that a control system seeks to regulate, such as temperature, pressure, flow rate, position, speed, or any other measurable attribute.
The thyristor also greatly improved the control system, allowing an SVC to detect and react to faults to better support the system. [8] The thyristor dominated the FACTs and HVDC world until the late 20th century, when the IGBT began to match its power ratings.
With feed-forward or feedforward control, the disturbances are measured and accounted for before they have time to affect the system. In the house example, a feed-forward system may measure the fact that the door is opened and automatically turn on the heater before the house can get too cold.
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A motor controller is a device or group of devices that can coordinate in a predetermined manner the performance of an electric motor. [1] A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and electrical ...