PLC Control Panel Basics
Have you ever wondered how an automobile assembly line is controlled?
In this video, we are going to talk about what controls large or small mechanical processes like an assembly line. That device is called a control panel.
Think of a control panel like the human body. Inside our bodies, we have vital organs that control and monitor our surroundings.
Similarly, a control panel is a metal box that contains important electrical devices that control and monitor a mechanical process electrically.
Let’s get started! First let’s talk about the enclosure, the metal box that contains all of the electrical devices of the control panel.
Enclosures are often aluminum or stainless steel and the size will vary based on the size of the process.
A control panel enclosure can have multiple sections. Each section will have an access door. The size of the enclosure is commonly referred to by the number of doors the enclosure has.
Each enclosure will have an electrical safety rating designated by UL, the “Underwriters Laboratories” who governs electrical safety.
They will also have an IP rating or NEMA classification which designates the enclosure to be indoor or outdoor, waterproof or water-resistant, suitable for hazardous conditions, dustproof, or explosion-proof.
Now let’s go inside the enclosure and talk about the non-electrical components that make up the control panel.
First, let’s talk about the back panel of the enclosure. The back panel is a sheet of metal that is mounted on the inside of the enclosure that allows us to drill mounting holes for different devices which leads us to our next component, DIN rails.
A DIN rail is a metal rail with a standard width used for mounting electrical devices inside.
The next component inside the control panel is the wiring Duct. Ducts allow us to route the wires in an organized and efficient way while also reducing electrical noise between devices.
Next, let’s get into the electrical components of the control panel!
The main circuit breaker is where the power comes into the control panel for all of the devices. This circuit breaker generally has a disconnect on the outside of the panel that allows us to shut off the power.
Always remember the topside of the circuit breaker will still have power. The power that comes into the panel can be anywhere from 480 volts to as low as 120 volts.
After the power comes into the panel from the main circuit breaker the power will be run into a surge arrester.
A surge arrester is a device that protects all of the electrical equipment inside the control panel from electrical surges or overvoltage. An electrical surge can come from a lightning strike or utility power surge.
In this video, we talked about the components of a control panel. Each control panel will have the main power source coming in that is distributed throughout the panel to varying devices for control and monitoring.
Control panels will come in different sizes but they all have similar devices that we talked about today.