{"id":2447,"date":"2021-11-23T12:53:00","date_gmt":"2021-11-23T12:53:00","guid":{"rendered":"https:\/\/www.axcontrol.com\/blog\/?p=2447"},"modified":"2023-09-25T16:36:54","modified_gmt":"2023-09-25T16:36:54","slug":"what-is-a-closed-loop-system","status":"publish","type":"post","link":"https:\/\/www.axcontrol.com\/blog\/2021\/what-is-a-closed-loop-system\/23\/11\/","title":{"rendered":"What is a Closed-loop System?"},"content":{"rendered":"\n
\"Closed-loop
Control loops can control speed, position, torque, temperature, etc. <\/figcaption><\/figure>\n\n\n\n

A closed-loop system will make automatic adjustments without external adjustment. The system uses a setpoint as part of the initial setup. <\/p>\n\n\n\n

Sound difficult? It’s not. Let’s break that down. <\/p>\n\n\n\n\n\n\n\n

Interacting With Closed-loop Systems<\/h2>\n\n\n\n

You’ve been using closed-loop systems for most of your life. You just didn’t know it. <\/p>\n\n\n

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\"Kitchen
Your kitchen has several closed-loop systems, including your refrigerator. <\/figcaption><\/figure><\/div>\n\n\n

One of the most-used closed-loop systems in your kitchen is your refrigerator. <\/p>\n\n\n\n

Think about the last time you went to grab a snack out of your fridge. Did you think about the temperature dropping as you stood with the door open, scanning the shelves? Probably not. <\/p>\n\n\n\n

You didn’t have to, because your refrigerator motor and compressor will click on automatically to compensate for the change in internal temp. That’s what refrigerators do. <\/p>\n\n\n\n

That’s a closed-loop system. The open door increases the interior temperature. A sensor automatically alerts the compressor to begin the cooling process again. This moves more refrigerant through your unit, creating evaporation, which cools the inside until the setpoint temperature is reached. <\/p>\n\n\n\n

Other Closed-loop systems<\/h2>\n\n\n\n

Electric irons, air conditioners, and ovens are other examples of everyday closed-loop systems. Cruise control could also qualify as a closed-loop. <\/p>\n\n\n\n

Take a look at our blog on bang-bang control <\/a>if you want to know a little more about these kinds of control systems. That blog also explains a little about PID control, which works in a different manner. <\/p>\n\n\n\n

Control Loops in Industrial Applications<\/h2>\n\n\n\n

Control loops also make up a fundamental building block in industrial control systems. <\/p>\n\n\n\n

In the example below, the controller could be many things, including a PLC (programmable logic controller), DCS (distributed control system), a discrete controller like a GP3000 series industrial PC<\/a>, or even a function block. <\/p>\n\n\n\n

\"Industrial
Industrial Process control loop diagram<\/figcaption><\/figure>\n\n\n\n

The above diagram is an example of a PID or intermediate control function that can generate any range of outputs. This means it can run at 1%, 50%, or 100%, or anything in between. <\/p>\n\n\n\n

As the left-hand side of the diagram shows, these systems can accept set points (SP) either locally or remotely. Local input might be from a panel, while remote input may be from a remotely placed HMI or other control equipment. However, the controller also responds to the feedback loop that feeds information back to the controller. This feedback loop offers a process variable that is then compared to the setpoint to determine when the system should stop. This is why closed loop controllers are sometimes called feedback controllers. <\/p>\n\n\n\n

In industrial control, control loops may be associated with the physical control of the motor shaft in relation to some other thing. So, for example, the position of a part, speed in reference to time, or the torque delivered by the motor. <\/p>\n\n\n\n

What are the Advantages of a Closed-Loop System? <\/h2>\n\n\n\n

Closed-loop controllers are superior to open-loop controllers in several ways. Closed-loop systems can<\/p>\n\n\n\n