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Process Control Loops: What are They and How do they Work?


Process Control Loops: What are They and How do they Work?

Process control loops are the core units in any industrial control system. Depending on how complex a system is and how many process variables need to be controlled, the control loops could exist in hundreds or thousands. The most common controllers used in industries today are the Distributed Control System (DCS), the Supervisory Control and Data Acquisition (SCADA) and the Programmable Logic Controller (PLC). A traditional control loop consists of three major parts that are the controller, a sensor/transmitter, and a final control element.

The Controller in Process Control Loops

This is the regulatory part that seeks to keep the measured process variable (PV) at a constant as indicated by the transmitter. This could for example be the temperature in a room. It also acts on error signals that are generated in the process and determines what control actions to take. To determine the control action to be taken, the controller performs an evaluation by either electronic signal processing, pneumatic signal processing or by a computer function, which is mostly used in industries due to the rapid growth of computer use.

The controller requires an input of a representation of the setpoint, that is, the reference value of the variable, and the measured indication of the controlled variable, both expressed in equal terms as the measured value. The final evaluation entails determining the action needed to make the controlled value same as the setpoint value.

The Sensor/Transmitter

This is the device that conducts the measurements and conversions of variables into analogous or electrical information. The term transducer may be used for a device that converts a signal from one form to another like for example converting a voltage into a proportional current. The sensor after measuring the variables transmits the measurements as electric signals back to the controller.

The Final control

It implements the real-life solutions taken by the controller by taking in input signals and transforming them into equal partitions of operations performed in the process. It performs the required changes in the controlled variables to make them equal to the setpoint. Some examples of this final control tools include the relay switches, the variable frequency drive and the control valves among others.

To better understand industrial control systems and the functioning of process control loops, it is important to undergo formal training. This kind of training is recommended for the following groups of individuals:

  • Multi-craft Technicians.
  • IT Technicians.
  • Automation Technicians.
  • Instrumentation Technicians.
  • Maintenance Technicians.
  • Anyone interested in a training on Process Control Loops.

Having a set of employees who have undergone thorough safety training on process control loops is beneficial because of the following reasons:

  • The employees will have a positive mindset on safety issues and will uphold safety standards.
  • It helps minimize the rate at which accidents happen in the industry. The workplace acts as a second home to workers as they spend most part of the day there. When safety is emphasized it would translate to more time being spent doing work rather than taking days off to deal with injuries.
  • Having your workers undergo a safety training is a requirement by the law and by most insurance agencies. This limits the number of lawsuits you would have to face and you could get compensation from your insurance agency in case an accident occurs. All organizations are required to have a safety management system that should be adhered to by all the members of the organization.
  • It will help save on cost. When injuries occur at a high rate in the industry, a lot of money is spent in compensating the injured workers and the insurance rates increase. This translates into less money being put into the production process and the level of output reduces.
  • It saves on production time. In case a worker is injured due to lack of proper safety training, they would have to take time off and in case of death, the line of production where they were based at stops until an appropriate replacement is found. Other workers may also need some time off to deal with the trauma they experienced after the accident.

Is a Safety Training Course Right for Your Business?

Are you interested in introducing your workers to safety training when dealing with process control loops? Get in touch with NTT Inc. today and register you workers for a seminar in Tuning DDC/ process Control Loops!

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