programmable logic controller and automation

unit 1

1. 191ECem-Plc and automation Handled by, Dr.R.Jenitha Assistant Professor, Dept of ECE

2. Google class room link oxu5e35

3. Unit 1

4. What is process? A systematic series of actions or operations producing an end result or product. Ex- Energy generation from fuels, water, wind etc , power transmission and distribution product manufacturing, packaging and distribution food processing

5. Building blocks of process control and instrumentation Sensors and Transducers Measurement and instrumentation Machines Control system

6. Process control loop Actuator Process Sensor Controller Set point Input Output

7. Sensor and transducer

8. controller

9. actuator

10. process

11. Input variable

12. Output variable

13. Practical example – juice packaging

14. Chemical reaction chamber

15. Patient monitoring system

16. Automatic lighting system

17. Short video about plc & automation

18. servomechanism Servomechanism, automatic device used to correct the performance of a mechanism by means of an error-sensing feedback. The term servomechanism properly applies only to systems in which the feedback and error-correction signals control mechanical position or one of its derivatives such as velocity or acceleration. All servomechanisms have at least these basic components: a controlled device, a command device, an error detector, an error-signal amplifier, and a device to perform any necessary error corrections (the servomotor).

19. servomechanism For example, an automotive power window control is not a servomechanism, as there is no automatic feedback that controls position,the operator does this by observation. By contrast the car's cruise control uses closed loop feedback,which classifies it as a servomechanism. The Boeing 777 is the first heavy jet plane engineered to fly with all major flight-control functions managed by servomechanisms. The design of this revolutionary plane is based on the so-called “fly-by-wire” system. In normal flight a digital signal communicates the pilot’s instructions electrically to control servomechanisms that position the plane’s control surfaces as needed.

20. Open Loop System In this system, an input is applied and an output obtained. Figure shows an example; assume an aircraft rudder controlled by an open loop system. The demand, made by the pilot on the rudder bar, is picked up by the transducer which converts it to an electrical signal i.e. the demand signal. This signal is amplified and fed to the motor, which responds by moving the load i.e. the rudder. There is no positional feedback and the pilot does not know if the rudder has adopted the position requested.

21. Closed Loop System In the closed loop system, the demand is made in the same way. In a basic system, positional feedback would be given to the pilot who would make adjustments accordingly but this is not practical with systems such as aircraft flying controls. Figure shows closed lo system

22. Applications Of Servo Automotive power steering uses hydraulic fluid under great pressure to power an actuator that redirects the wheels of a car as needed. The driver gently turns the steering wheel and the power-assist servomechanism provides much of the necessary energy needed to position the wheels. High-performance airplanes need special servo-mechanisms called flight-control systems to compensate for performance instabilities that would otherwise compromise their safety.