Unit 1 PPT.pptx on Elements of Industrial automation chapter 1

Elements of Industrial automation
chapter 1

1. Elements of Industrial automation Un it 1 Industrial control circuits 16M Unit 2 PLC Fundamentals. 14M Unit 3 PLC Programming basics. 14M Unit 4 PLC Wiring diagrams and Ladder logic. 18M Unit 5 SCADA and DCS. 08M

2. Unit 1 Industrial control circuits

3. Introduction Industrial automation is the use of automatic or robotic devices to complete the given manufacturing task. The technology that can perform all the processes without manual operator is called Automation Industrial automation is becoming increasingly important in the manufacturing process because automatic or robotic devices or machines are capable of handling every task quickly and efficiently.

4. Need of Automation To achieve complete control of the manufacturing process. To achieve consistency in manufacturing. To improve product quality and accuracy. To work in difficult and hazardous atmosphere. To increase productivity. To quickly change over from one product to another. To lower the cost, scrap and rework.

5. Benefits of Automation Increased productivity. Improved product quality and accuracy. Increased flexibility and convertibility. Reduces manpower. Reduction in personal injury or accidents. Reduces cost of product. Increased profit. Increased productivity. Improved product quality and accuracy. Increased flexibility and convertibility. Reduces manpower. Reduction in personal injury or accidents. Reduces cost of product. Increased profit.

6. Programmable logic controller

7. Programmable logic controller PLC is a digital system consists of program memory and data memory to store program and data. It accepts digital or analog signals through input module then processes on that signal using ALU timer,counter and other specific function blocks and after process it gives analog or digital output over output module as per the requirement of an application.

8. Input Devices: In a PLC system there will be usually be dedicated modules for inputs and dedicated modules for outputs. An input module detects the status of input signals such as push buttons,switches, temperature sensors etc. An output module controls devices such as relays,motor starters,lights etc.

9. 1.Push Button :

10. Explanation: Push buttons are the ones that you will usually see as START or STOP buttons in a PLC control system. It operates by either MAKING contact (Make) or by BREAKING contact (Break). Hence, pushbuttons are divided into two categories: Normally open or Normally closed.

11. a)Normally open (NO):

12. a)Normally open (NO): Normally open push buttons, when connected to the circuit, normally make an OPEN circuit. In this scenario, the current can NOT flow through the switch, as there is no electrical continuity. Pushing the button will make its metal contacts touch with each other, closing the connection between the two connected terminals and hence allowing the current to pass.

13. b)Normally closed (NC):

14. b)Normally closed (NC): Normally closed push buttons, when connected to the circuit, SHORTS the connected terminals. In this scenario, current can already flow through the switch. This means that if you connect a normally closed push button to a circuit, the circuit will turn on immediately because there is electrical continuity already. This means pushing the button will make its metal contacts touch with each other, closing the connection between the two connected terminals.

15. 2.Selector Switch: Selector switches are still manually operated switches, however instead of being normally open or closed, there are more than two contacts to select from. The usual example is found in electric fans, where you can select a number that then dictates the speed of the fan’s motor. This process actually selects a varying load for the motor in order to control its speed.

16. 3.Limit Switches:

17. 3.Limit Switches: Limit switches, as the name implies, change state when a predetermined limit is reached. These are actually useful in automation because you can set a limit (using the limit switch) where a specific process stops. There are also different types of limit switches which allow us to choose the physical quantity to limit in our control system design.

18. Types of limit switches: a.Temperature Limit Switch :

19. a.Temperature Limit Switch : Also called Thermostat, the temperature limit switch is used to detect temperature changes in your system. They can also be Normally Open and Normally Closed, depending on what type is used. This dictates the actual Industrial application that it can be used in— whether it be an overheating prevention, or even just maintaining a certain temperature of materials.

20. b.Pressure Limit Switch:

21. b.Pressure Limit Switch: Pressure switches are most commonly used in containers where the pressure of liquids or gases is crucial. They change their state whenever a liquid or gas in a tank reaches a high enough pressure. Again, they can either be Normally Open or Normally Closed switches.

22. b.Pressure Limit Switch: When the pressure inside a tank increases to a high amount, the difference between the atmospheric pressure and the pressure inside will make the fluid (liquid or gas) inside “try to escape”. Using pressure limit switches allow us to prevent that scenario.

23. c.Level limit switch:

24. c.Level limit switch: Level switches—more commonly called Level Sensors, are used to control the height of a liquid inside a container, usually a tank. They are most commonly used in conjunction with inlet and outlet valves in a liquid level control system, or in a heating and mixing application.

25. 4.Proximity switches: When the proximity switch senses an object nearby,the state of the switch will change,and the input channel to which the proximity switch is wired, will indicate an ON state. Both the electronics in the switch and the PLC card are powered by the same 24 volt DC power supply.

26. 4.Proximity switches: Proximity switches open or close an electrical circuit when they make contact with or come within a certain distance of an object. Proximity switches are most commonly used in manufactuing equipment, robotics and security systems.

27. 5.Pressure switch: A pressure switch is a form of switch that closes an electrical contact when a certain set fluid pressure has been reached on its input. The switch may be designed to make contact either on pressure rise or on pressure fall.

28. Applications of pressure switch: Safety devices. Alarm. Control elements within a system. Boiler. Steam turbines Steam power plant. Electric motors. Gas compressors.

29. Output Devices: Output devices are operated by the PLC using the DC voltage at the output. Different output devices are: Relay Contactor Solenoid valve Solid state relay

30. 1.Relay : Relays are electrically operated device in which changing a current in one electrical circuit switches a current ON or OFF in another circuit. They have Normally open (NO) or Normally Close (NC) contacts which are ON or OFF,when coil of relay is energized or de-energised.

31. Working : The relay is electromagnetic device following figure shows an electromagnetic relay.

32. The relay consists of coil with a core inside.It is connected to a power supply through a switch. In addition ,it will have an armature placed close to the coil. There will be one moving contact point armature which can make contact with a fixed contact when moved. When there is a current through the coil,the relay coil gets energized and the core of the coil becomes an electromagnet. It pulls the armature down and the contact closes.

33. When the relay switch is OFF, the relay coil is not energized.So the armature remains in the position shown and the contact remains open. The device will remain ON so long as the relay coil is energized. In this system there is no relation between the power supply use for energising the relay coil and power supply of the device This is how we are able to control a high power device using a very low power relays.

34. 1.Relay :

35. We can think of a relay as an electromagnetic switch. Apply a voltage to the coil and a magnetic field is generated. This magnetic field sips the contacts of the relay in causing them to make a connection. These contacts can be considered to be a switch. They allow current to flow between 2 points thereby closing the circuit.

36. Lets consider the following example. Here we simply turn on a bell (Lunch time!!!!)whenever a switch is closed. We have 3 real-world parts. A switch, a relay and a bell. Whenever the switch closes we apply a current to a bell causing it to sound. Notice in the picture that we have 2 separate circuits. The red indicates the DC part. The blue indicates the AC part. Here we are using a dc relay to control an AC circuit.

37. When the switch is open no current can flow through the coil of the relay. As soon as the switch is closed, however, current runs through the coil causing a magnetic field to build up. This magnetic field causes the contacts of the relay to close. Now AC current flows through the bell and we hear it.

38. 2.Contactor :

39. A contactor is an electromagnetic device composed of a frame (or core) with an electromagnet coil,some movable contacts and some fixed contacts. Basically contactor is a form of relay,but relays are used for switching small current devices (less than 10A) whereas contactors are used for switching heavy current devices (greater than 10A). Fig.shows the contacter with 3 N/O contacts and one N/C auxiliary contact.

40. Contacter consists of three movable contacts mounted on the plunger with insulater. The plunger moves within the bobbin with contracts. To create the electromagnet,a copper wire is wound the bobbin.Inside the bobbin there is a spring which places the plunger away from the coil. When electric current will flow through the coil,it gets energized and magnetic field will be generated which pulls the plunger into the core along with the movable contacts.

41. Then these movable contacts physically touch the fixed normally open (N/O) contacts and they become close and auxiliary normally close contact gets open. When coil is de-energized then closed contacts gets open and open contact gets close because spring push the plunger towards right.

42. 3.Solenoid Valve : Solenoid valves are used to convert electrical energy into mechanical energy.

43. This top part is the solenoid and the bottom part is the valve, therefore making a solenoid valve. These valves do come in a variety of shapes and sizes.

44. Why to use solenoid valve? These valves allow engineers to autonomously and remotely control the flow of fluid within a system. This fluid can be a liquid or a gas. For example water, air, natural gas, oil, steam, refrigerant etc. the list goes on and on. The solenoid coil is used to operate the valve, by passing an electrical current through it to create an electromagnetic field and operate the valve. This means if it is connected to a controller, it can be operated autonomously and remotely by a computer without the need for engineers to run around physically opening and closing valves. This allows systems to run much more efficiently and safely.

45. Where do we use solenoid valves? Solenoid valves can be found in everything from washing machines to space rockets, although we’re going to focus on industrial applications. Example: Beverage production In industrial applications we can use these vales to precisely control the flow and mixing of fluids, for example to pour a perfect amount of fizzy drink into a bottle on a production line.

46. How do they work :

47. When we pass an electrical current through a coil, we generate an electromagnetic field. This magnetic field is what controls the valve. We have two types of valves, the normally open and the normally closed types

48. Normally Closed Solenoid Valves: Inside the valve we have the armature. The solenoid is placed over this and completely surrounds the armature so that it’s at the centre of its magnetic field. Inside the cylinder of the armature is the plunger and spring.

49. The spring pushes the plunger down in a normally closed type valve. Because the plunger is pushed by the spring, it will sit in the down position to close the valve indefinitely. But, if the coil receives an electrical current then it will generate an electromagnetic field and this magnetic field passes through the plunger and will cause it to move upwards against the spring therefore opening the valve. At the centre of the coil the magnetic field lines are the most compact and therefore the strongest. This is why we place the plunger in the centre. Once the electrical current is stopped then the magnetic field disappears and the spring will force the plunger down again to close the valve.

50. 4.Solid state relay (SSR) : A solid-state relay (SSR) is an electronic switching device that switches on or off when a small external voltage is applied across its control terminals. The relay may be designed to switch either AC or DC to the load. It serves the same function as an electro-mechanical relay, but has no moving parts. We have to give 4-32V DC in coil to operate and we can get 24-280V AC

51. SSRs employ semiconductor switching elements, such as thyristors, triacs, diodes, and transistors. Furthermore, SSRs employ optical semi-conductors called photocouplers to isolate input and output signals. Photocouplers change electric signals into optical signals and relay the signals through space,thus fully isolating the input and output sections while relaying the signals at high speed.

52. Characteristics of SSRs : They provide high speed,high frequency switching operations. They have no contact failures. They generate little noise. They have no operation noise.