DCS

# Control Function can be applied in DCS

In DCS control, basically it is used for a system of controlling devices so that they can be controlled electronically using standard signals that exist and can be applied as follows

### Single control loop:

Controls that can be done by DCS can make arrangements for tools in one or more loop circuits.

Single Loop is a control system that performs settings where the measurement results are directly controlled and the calculation results from error correction will be transferred to the actuator as feedback.
This single loop can also be called the feedback control system

Cascade control is a control system that can be carried out by DCS systems where it is needed in a loop control that requires an example level control system in the paper machine is a heat exchanger.

Control is often also called master and slave control where the master is the first controller while the slave is the second controller that gets the remote input signal from the master loop

### Batch control:

Batch system control is a control system that occurs due to repeated shutdown and start up operations with limited results according to orders from consumers.

The batch control system on the DCS functions to keep the control from becoming saturated so that when the control is restarted the actuator tool can be in a stand-by position according to the needs of the product to be made

The use of a batch system on DCS in a paper machine is to keep the control device working properly if the engine stops to replace the product because with this system the operator just needs to enter the set point to be achieved according to the production target.

### Selective Control

Selective control is a control system where there is one process that has two manipulated variables (measuring instruments) with only one variable control (actuator).

This selective control uses the High and Low signal selector which is represented by “<” for low and “>” for high. This selective control works so that a process can run well for example for a tank that will be flowed with a pump, using transmitter levels and to fill the tank using flow control this is needed so the tank does not overflow, with selective control systems can be determined when the control valve must open or close with the dominant signal originating from the level and flow meter.

### Ratio control:

Ratio control is a control system commonly used in a process that requires a mixture of two or more components with a certain comparison. An example of a control ratio is the mixing of chemical A and B with a certain ratio, where the desired comparison results must always be the same. A / B

### Sivaranjith

Instrumentation Engineer