What is a PLC Panel?

PLC Panel

Have you ever wondered: what are all of the components that get installed into a PLC panel and why are they needed? Well you’re in luck! We will take a deeper look into the internal workings of a common PLC panel and it’s components…

Put simply, a PLC panel is a special steel box that contains electrical components required to run a factory machine or process.  PLC stands for Programmable Logic Controller, an industrial hardened computer usually found inside factory control panels.  High voltage components are what makes up a lot of the other items found inside.  What are the other components?  Let’s take a look at the two types of components:

PLC Panel: Power Components:

	Rotary Disconnect	This is where the electrician connects the incoming power wires.  It can come with fuses or not.  It rotates using the black or yellow handle on the door of the panel to turn power on or off
	Power Distribution Block	This is a block usually made of machined aluminum.  It has a couple larger wire connecting holes in the top, and multiple smaller wire connecting holes below.  It is used to take a large wire and split it up into smaller wires for use with many different components in the PLC panel
	Branch Circuit Breakers	These are used to protect against short circuit (and overload in some cases) for each load, such as motors, heaters, etc.
	Transformer	This will convert the high power voltage down to a lower control voltage for common control devices such, as a PLC or HMI
	Power Supply	This will convert the high power voltage down to a lower safe control voltage for common control devices, such as a PLC or HMI
	Motor Starter	The motor starter (or contactor) turns on motors at full voltage and full speed
	Variable Frequency Drive (VFD)	VFD is a type of motor controller is able to adjust motor speed and also monitor other motor data as well
	Motor Soft Starter	This motor controller starts a motor slowly over time, ramping up to full speed

PLC Panel: Control Components:

 

	Supplementary Circuit Breaker	This is used to protect expensive control components and devices of the PLC panel
	Master Control Relay (MCR)	A master control relay is a used to implement a safety circuit that will remove power from all output devices in the event of an emergency.  It is usually paired with a red mushroom-head pushbutton
	Ethernet Switch	Used for network communications between smart devices, the PLC, the HMI, and other components
	Programmable Logic Controller (PLC)	The PLC is the industrial computer that communicates and controls all the components, motors, and devices in the machine or process
	Human Machine Interface (HMI)	The HMI is the graphical display that the operator uses to configure and operate a machine or process
	Input/Output (IO) Module	This is the interface module for connecting wiring from the PLC to the components and devices to be controlled
	Operator Pushbutton	A pushbutton the operator uses on the front of the panel to control the machine or process
	Terminal Blocks	These are used to connect and splice internal panel wiring and field device wiring

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