Identifying Industrial Control Panel Components
We're going to go through the basic components that you will find in an industrial control panel but beyond these basics, one of the best ways to get familiar with industrial control panel parts is to start browsing parts offered by automation suppliers. And by far our favorite automation parts supplier is Automation Direct. They offer quality parts at reasonable clearly stated prices. They have great product support. And for the purpose of this article, they have a web site that is well laid out and makes it easy to expand your knowledge of the components we are going to discuss in this article.
For example below we will explain to you what a "Drive" is. For further learning, click the "Drive" category in the left pane of Automation Direct's website. There you can learn about different types of drives such as DC drives, AC drives, and AC soft starters. Additionally you can learn about differnet types of AC drives such as Volt/Hz, sensorless vector, and drive options such as DC braking and encoder options.
You'll find this method offers you much more real world and up to day information than you will find in your typical text book.
We're going to continue with the control panel we used in the "What is a Control Panel" lesson and identify all of the components in it plus "Field" components that would be connected to it. Click the image for a larger view.
1. Transformer - Transformers are used to convert one AC voltage to another AC voltage. Most popularly would be converting 480VAC to 120VAC for creating control power.
2. Programmable Logic Controller (PLC) - This is the "brains" of the control panel. It reads inputs and executes code based off of them, then adjust the outputs of the control panel. Details of what inputs and outputs are plus further details of how a PLC operates are in later lessons
3. DC Power Supply - Where as a transformer converts an AC voltage to another AC voltage, a power supply converts AC or DC to a DC voltage. Most commonly it converts 120VAC to 24VDC
4. Ethernet Switch - Just like the Ethernet switch that you probably have at your house, many control panels have Ethernet switches for connecting PLCs, HMIs, networked I/O, and information systems.
5. Circuit Breaker - Circuit breakers protect loads from pulling too much current.
6. Disconnect Switch - The disconnect switch will usually disconnect all electrical power from the control panel. Using Lockout Tagout procedures, this should be isolated when working on the control system.
7. Wire Duct - Wire duct is usually ran around the perimeter of the panel and in between rows of electrical components to house the wires that interconnect the electrical components
8. Terminal Blocks - Terminal blocks are connection points to tie wires together. Some are for internal connections and some are for connecting field components to terminal blocks.
9. Breakout Boards - Breakout boards are specialized terminal blocks that can be used to simplify wiring of components that have connectors that would normally need soldering or reduce the labor of internal wiring.
10. Fuses - Fuses, like circuit breakers protect loads from pulling too much current but are only good for one use. That doesn't mean that circuit breakers are better since they can be reset and reused. Each has its place.
11. Relays - A relay is an electronically or magnetically operated switch. Power is applied to the coil which creates a magnetic field that switches the relay contacts.
12. DIN Rail - Is a metal rail that allows the mounting of many industrial control components. It stands for Deutsches Institut für Normung which is who published the original specifications for it. A note to instructors, don't make DIN=Deutsches Institut für Normung a test question. I, along with every other Systems Integrator, has to look that fact up. Most of us don't even know that DIN is a German acronym.
13. Overload - An overload protects loads, usually motors, from pulling more amps that the overload allows. They usually monitor three motor phases.
14. Contactor - A contactor is the same as a relay but is usually larger in size for a motor and consist of three poles.
15. Terminal Ground Blocks - A terminal block ground is usually internally grounded to the panel. You should learn to identify them, they are usually green or green/yellow.