How can you select the best sensors and actuators for a PLC system in plant engineering?

First of all Sensor Is not selected based on PLC system. PLC is selected based on sensor. Secondly sensor quality have some parameter so that we can say best for our project. 1. Requirement of hazardous compliance 2. Requirement of accuracy and response time 3. Suitability of process parameter operating as well as design 4. SIL Requirement, if any 5. Meter reading deviation per year Any many more Similarly actuator is selected with some additional parameter

The first step is understanding what are your process requirements. Next, you determine what are the location of the field devices, the distance from the control panel, the operation pressures and temperatures. Each PLC manufacturer has analog and digital input and output cards for their modules. With the analog inputs it’s excellent for pressure,pH,flowmeter and temperature sensors, based on the distance from the control panel you can choose between 4-20mA or 0-10 volts. The 4-20mA is best suited for long distance applications as it reduces signal interference. Analog outputs are best suited for control valves and VFDs. The digital outputs and inputs used for level sensors, pressure switches, valve state (open/close) and solenoid control.

Selecting sensors and actuators for a PLC system involves considering the type of control system, the number of I/Os, and their location. Sensors should be chosen based on the physical quantities they need to measure or detect. Actuators must meet conditions like mounting space and control linkage. It’s also important to consider the type of PLC applications, such as automation. Ultimately, the selection should align with the specific requirements of your plant engineering project.

There are many considerations that must be taken into account. Firstly, the input and output signals of the PLC. Taking for example so modules of Allen Bradley PLC gives out only voltage or current or both. Some modules only deals with range of load ie 0-500ohms or 501-1000ohms. Secondly, some sensors and actuators are chosen due to their safety ( intrinsic safe or). Thirdly, the importance or type of medium being measured ie rotameter or vortex for flow measurement.

To select the best sensor, I also would like to add several points as below: 1. wet part material suitability with process service/fluid. 2. Range-ability. How the process characteristic will be. Is there any different for process parameters during start up and during normal running? The sensor range-ability should consider any scenario that might be happen. If the range cannot cover, then some design needs to be considered to provide proper measurement and avoid unnecessary error due to unreliable measurement. 3. Your process plant characteristic for reliability. And several other considerations and descriptions that I would like to share but I can not share due to character limitations. Hopefully, I would be able to share in other chance

Confused. You wouldn’t use a linear actuator for a rotary motion, or vice versa. Or a thermistor to measure pressure. Are we really this basic in this discussion? Snark aside, yes, there ARE better, cheaper, more reliable solutions to a common question. Dig around. It’s amazing what a few simple internet searches can yield in a short period of time.

The second step in selecting sensors and actuators for your PLC system is to choose the appropriate types based on the physical variables and actions involved in your process. For temperature measurement, options like thermocouples, RTDs, or thermistors can be considered as sensors. If valve control is needed, solenoids, motors, or pneumatic actuators can be used as actuators. Evaluate the features and performance of different types to find the best fit for your specific process requirements.

Accuracy & Precision: These two terms do not mean the same thing, though they are often related. Accuracy has to do with how close the sensor reading is to the true value while Precision refers to the ability of the sensor to detect small changes. #Actuator: pneumatic actuators, hydraulic actuators and electric actuators. To choose the right actuator, it is recommend that you consider certain factors. First, you will need to think about the desired movement. There are two types of movement available for actuators: rotary actuators (which produce a rotary movement) and linear actuators(which produce linear movement). Next, you will need to consider how much torque (if rotary) or force (if linear) the actuator you choose should develop

Stop trying to "create the black thread", if part of the system already exist and there are one or many "experts" on that system, so, why do you spend resources poorly developing the same system?

This is really “Bread and Butter” engineering. If you can’t scope out the specs of the device and think through the interrelationships with the processor, you need to think some more. For God’s sake, do NOT depend on product marketing fluff or other people’s recommendations. YOU are responsible for the end product. You don’t get to blame others if you’re too distracted to do good analysis.

The third step in selecting sensors and actuators for a PLC system is to thoroughly check their compatibility with the PLC itself. it's involves considering various electrical characteristics, such as voltage, current, and power ratings, as well as signal types , communication protocols , and wiring and connection methods . It is crucial to consult the PLC specifications and manuals to ensure that the chosen sensors and actuators are supported and compatible with the specific PLC model and software being used. By ensuring compatibility, seamless communication and effective integration between the components and the PLC can be achieved, leading to optimal performance and functionality of the overall system.

This is basics! If you already had two devices and change one of them is a big problem, try to find the correct bridge, like a communication converter.

Most manufacturers produce sensors with approximately the same characteristics, so for most problems, choosing a sensor manufacturer comes down to achieving the optimal price/quality/delivery time ratio. It is also necessary to take into account the customer’s wishes when choosing a manufacturer; the customer needs unification to maintain a spare parts warehouse.

Be aware of those brands that give you a realy good price at begining but once you need a replacement it cost twice, yes, you KEY of sciENCE! Devices or systems that are cheap at the beginning become more expensive after a short time, either due to failures or maintenance or in the end it does not work and you have to invest again in something better.

Everything is prone to failure! Trust no more in "it's new" or "arrived direct from fabric", always take time to test your equipment before pay! If you are new on this, ask for and listen to the advise of experienced people.

Continuing to research sensors and actuators after you have designed the system could lead to improvements in downtime or performance. As well as condition monitoring to get an idea of when to perform maintenance on the equipment.

Most projects I've been involved wouldnt be overly meticulous on the machine working cylce, let alone for the sensors/actuators selection. Most of the time is just choosing the cheapest crap available and hope for the best. You can always blame software afterwards.

I would use the following checklist to start with my sensor or actuator selection: 1. Application Requirements: Eg. type of sensor needed & actuator required for the application. 2. Compatibility: Communication compatibility with the controller. 3. Accuracy and Precision: Use the sensor with the desired accuracy as the price varies on this point. 4. Environmental Conditions 5. Response Time 6. Redundancy and Reliability 7. Safety Requirements 8. Cost-Benefit Analysis 9. Maintenance and Calibration ease 10. System Scalability for future changes 11. Vendor/Brand Reputation 12. Testing and Validation 13. Documentation & Training 14. Service Support