Tag: Industrial control
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Key Causes of Uncertainty in Control Systems
One of the objectives of a control system is to achieve good plant performance in the face of uncertainty. The major sources of uncertainty in control are: Unmeasurable perturbations Modelling errors Unmeasurable Perturbations Unmeasurable perturbations produce output deviations. With a … Read more
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How Synchros are used as Position Transducers
Let’s consider the transformer in Figure 1.0 whose secondary winding can be rotated with the respect to the primary winding. Figure 1.0 Synchro torque transmitter At an angle ϴ, the output voltage will be given by: Vo = KV… Read more
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Centralised vs. Decentralised Control Systems
Centralised control is usually carried out via computer software, having as inputs all the available sensors and producing signals for all the available actuators in the system. This control strategy is the most powerful, at least in theory, capable of … Read more
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Actuators as Automation Components
An actuator is normally controlled by the controller. The actuator, in turn, changes the output of an automated process. The actuator in an automated process may in actual fact be several actuators, each of which provides an output that … Read more
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Adaptive Control System
Adaptive control system adjusts to changes and modifies its parameters to fit the prevailing circumstances. The adaptive control system is based on the use of a microprocessor as the controller. Such a device enables the control mode and the control … Read more
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Control Modes in Automation Systems
The mode of control is the way in which a control system makes corrections relative to an error that exists between the setpoint of a controlled variable and its actual value. We have a number of ways (i.e. control modes) … Read more
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The Performance Limits for PID Controllers
PID Controllers can be applied successfully to most control problems in process control, electrical drive systems and servo mechanisms due to the fact that most of these processes have a dynamic behaviour that can be adequately approximated by a second-order … Read more
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What is Selective Control?
In a number of process control problems, we may have more measurements (controlled variables) than manipulated variables. Hence, it is impossible to eliminate errors in all the controlled variables for arbitrary setpoint changes of disturbances by using only simple (single-input/single … Read more
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5 Control Techniques – Their Features & Applications
We have a number of control theories that have been put forward on how to design control laws to accomplish various purposes. Generally they can be classified as follows: Classical Control This control technique deals with the behaviour of dynamical … Read more
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Hierarchical Control Strategies for a Process Plant
In a process plant, we typically have a number of control goals that require different algorithms and types of information from the process; from the level closest to the process to the plant-wide control. All these activities ought to be … Read more