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Today you will learn about PIDs.
Specifically, what they are and when do we use them with automation and PLCs.
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So what is a PID controller?
It is an acronym that stands for proportional,integral,derivative.
If you need to keep something constant,
like a temperature for example,
then this is the way to do it.
Essentially, it uses a control loop feedback
to ensure the output wanted is what you will get.
Simply, you put a setting in the controller
and it will keep the output constant based on feedback from some input,
typically some kind of sensor.
Something you probably encounter every day
that is essentially PID control, is your cruise control in your vehicle.
First, you get to the speed that you want to be going.
Then you set your cruise control.
The cruise control sends output signals to your throttle to regulate the speed.
A speed sensor provides your control loop feedback
to tell the cruise if the car should speed up or slow down,
or how much more or less throttle to provide.
A common standalone type that we use in manufacturing and industry,
is a temperature controller PID.
These controllers are pretty simple to use and setup,
plus they do a great job at controlling temperatures of a variety of equipment.
Let’s take a look at how they work.
For our example, we will look at a PID controller
that controls the temperature of heat tracing on process piping.
First, we need to enter a set point,
200 degrees Fahrenheit for our example.
Now the controller will give a signal to the output
to start heating up the heat tracing.
The control loop feedback is in the form of a thermocouple to read the temperature.
For our example, the PID controller
can work as on-off control for the heat tracing.
Along with the set point of 200 degrees,
we will set the controller at a couple of degrees above and below 200 as well.
When the thermocouple reads 202 degrees
it will turn the heat tracing off.
When it reads 198 it will turn it back on.
This is the simplest form of PID control.
We also have the option of setting up a PID controller with a PLC.
Instead of the standalone unit,
we can use the input and output cards already on our PLC.
The process variable, or control loop feedback,
would be wired to our input card
and programmed into the PID.
Our output being controlled is wired to our output card.
The PID in the PLC can do all of the math
and make the decisions based on the variables and set points.
No matter which way you decide to set it up,
a PID is an excellent choice for an automated process.
Let's look back at today's information.
A PID controller is a proportional integral derivative controller.
It can keep an automated process like temperature,
pressure, or flow, constant, for you automatically.
PIDs use a control loop feedback
or process variable to monitor where the output should be.
These usually come in the form of sensors and meters.
PIDs come in many different forms
including standalone units and PLC programming.
We can use our input and output cards
along with programming software to set up a PID.
I hope this video really helped you get a grasp of how to use a PID.
They are a very handy tool to use.
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