Answer to Question #261209 in Electrical Engineering for Henry

Question

a) Describe three types of PLCs and their application including advantages and disadvantages of each type. 

 

b) Describe the four main components that identify the operating characteristics of a PLC.  

 

c) Describe the four different types of external input and output devices that can be connected to a PLC for plant control or monitoring. 

Answer 1

Compact PLC

There might be several modules within a single case. It has a set number of internal and external I/O modules and cards. As a result, it lacks the ability to expand the modules. The manufacturer would decide on every input and output.

Modular PLC

This type of PLC allows for various expansions via "modules," thus the name Modular PLC. The number of I/O components can be raised. It is simpler to use because each component is self-contained.

PLCs are classified into three varieties based on their output: relay output, transistor output, and triac output. The relay output type is best suited for devices with both AC and DC outputs. PLCs with transistor outputs perform switching operations and are found within microprocessors. A PLC is classified as Mini, Micro, or Nano based on its physical size.

Advantages of PLC over Relays: PLC improves the automation system's dependability, adaptability, and precision. When compared to other automation technologies, PLC (particularly Compact PLC) has a cheaper cost. PLC programming is simple to develop and comprehend.

Connecting cables requires much too much effort.

It operates on a set circuit.

Manufacturers of PLCs exclusively provide closed-loop design.

Because PLC is a new technology, it should necessitate training.

PLCs have a constraint while operating in high temperature and vibration environments.

PLCs are small, durable devices that do not require fans, air conditioning, or electrical filtering. There are three parts to a Programmable Logic Controller. Processor, power supply, and an input/output (I/O) section are the three PLC components.

In a PLC system, inputs and outputs are typically separated by specific modules. The state of input signals such as pushbuttons, switches, temperature sensors, and so on is detected by an input module. An output module is responsible for controlling devices such as relays, motor starters, lights, and so on.