Electropneumatics Circuits PDF

Course Description: It deals with the study of the basic principles and fundamentals of hydraulics and pneumatics and electro-pneumatics and its application. It deals with the interpretation of standard symbols used in hydraulics, pneumatics, electro-pneumatics it also deals with co...

Course Description: It deals with the study of the basic principles and fundamentals of hydraulics and pneumatics and electro-pneumatics and its application. It deals with the interpretation of standard symbols used in hydraulics, pneumatics, electro-pneumatics it also deals with components’ familiarization and description, circuit diagram, circuit design, interpretation and analysis.  Course Outline: 1. Principles of Hydraulics 5. Basic rules in circuit – Fluid Power and hydraulics diagramming – Pressure, force and area - The rest position – The Pascal’s Law and the Gas - Circuit lay-out and guidelines Laws - Motion and step diagram 2. Introduction to Pneumatics -Sequence charting - Basic pneumatics system 6. Basic electro-pneumatics - air production system - Direct and Indirect control - air consuming system - Logic functions 3. Hydraulics, pneumatics - Dominant set/reset memory components -Time dependent control - actuators - Sequence control - directional valves - auxiliary valves 4. Basic circuits -Elementary function - flow amplification - signal inversion - memory function - delayed switching on - delayed switching off - pulse on  References 1. Fluid Power; Sullivan 2. SMC Pneumatics Training Manuals 3. FESTO Didactic training Manuals 4. Basic Pneumatic Lab. Manual, Dr. San Diego Electropneumatic/hydraulic Control and Design Objectives The aim of this lecture manual is to guide the students to the fundamentals of electro- pneumatics/hydraulics, To acquaint them with the elements currently used in the industry, their characteristics, functions and symbols. To be able to design, build and maintain electro-pneumatics/hydraulic system and controls independently. HYDRAULIC CONTROLS AND DESIGN TOPIC OUTLINE:  Application of hydraulics  Types and properties of hydraulic fluids  Hydraulic power generation and transmission  Standard hydraulic symbols  Hydraulic working elements  Hydraulic valves and components  Electro-Hydraulic controls  Practical Exercises BASIC LOGIC CIRCUITRY USING RELAY CONTROL 1.) Allocation / Assignment 2.) Negation: NOT function DIRECT AND INDIRECT SIGNAL ACTUATION 1.) Direct Electrical 2.) Indirect Electrical Actuation Actuation Input Switch or Signal Receivers (eg. sensors) directly powers the load of the system. Input Switch or Signal Receivers (eg. sensors) actuates a relay which then Disadvantage: No electrical isolation actuates the load bet. Control circuit and power circuity; each input can Advantage: Electrical isolation; mutiple only drive one output output BASIC LOGIC CIRCUITRY USING RELAY CONTROL 3.) AND function 4.) OR function SIGNAL STORAGE IN THE CONTROL SECTION 1.) Dominant-ON 2.) Dominant-OFF If both ON and OFF switches or inputs If both ON and OFF switches or inputs are actuated, the output is actuated -> are actuated, the output is unactuated ON -> OFF SIGNAL STORAGE IN THE POWER SECTION Double Solenoid Valves are inherently memory valves which stores signal actuation and state of the valve position. By just applying a pulse on one solenoid coil, the valve switches to a corresponding position and maintains until a pulse at the other coil is applied (click to play Fluid-SIM animation)  PART C: READING & INTERPRETTING CIRCUIT DIAGRAMS/DRAWINGS ELECTRICAL CIRCUIT DIAGRAM -ElectricalCircuit Diagrams are documented and standardized drawings of the electrical connections of the devices of the whole system -It doesn’t show the actual installation and mechanical locations of the devices and the actual wiring routes but it shows how the devices are being interconnected with cable lines through their various terminals - In addition it shows each devices designation codes for easy tracing and troubleshooting; and added devices information (eg. rated speed, cable diameter) - EN 61082-1:2006 is a standard for the preparation of documents for electrotechnology and defines how electrical circuit diagram of a system is drawn and documented. IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations SAMPLE ELECTRICAL CIRCUIT DIAGRAM- EN 61082-1 HYDRRAULIC CIRCUIT DIAGRAM -Pneumatic & Hydraulic (Fluid Power) Circuit Diagrams are documented and standardized drawings of the tubing connections or pipe connections of the fluid power devices of the whole system - It doesn’t show the actual installation and mechanical locations of the fluid power devices and the actual pipe routes but it shows how these devices are being interconnected with tubings or pipelines through their various ports - In addition it shows each fluid power devices designation codes for easy tracing and troubleshooting; and added devices information (eg. nominal pressure, pipe diameter) - One standard for fluid power circuit diagram is the DIN ISO 1219-2 standard. DIN ISO 1219-2 STANDARD  All components of a circuit have the same main code.  Letters are allocated in relation to the component.  Multiple components within a circuit are numbered serially  Pressure lines are designated with P and are separately serially numbered. Drives: 1A1, 2A1, 2A2,... Valves: 1V1, 1V2, 1V3, 2V1, 2V2,... Sensors: 1B1, 1B2,... Signal input: 1S1, 1S2,... Accessories and Source: 0Z1, 0Z2, 1Z1,... Pressure lines: P1, P2,... SAMPLE DIN ISO 1219-2 CIRCUIT DIAGRAMS Detailed Diagram Simplified with Technical Diagram Information COMPARISON OF PNEUMATICS AND ELECTROPNEUMATICS ADVANTAGE OF ELECTRICAL/ELECTRONIC CONTROL AS COMPARED TO PNEUMATIC CONTROL  Increased reliability (less wear, mechanically moving parts)  Reduced planning and commissioning complexity, particularly in complex control systems  Reduced installation expenditure  Simple exchange of information between several controllers ELECTRICAL SWITCHES Breaks or closes circuit connections used to turn on/off a system, a device (load) or a station. Switches are primarily distinguished by their contact configuration: 1. Normally open (make): path 3 to 4 2. Normally closed (break): path 1 to 2 3. Changeover contacts: path 1 to 2 or 1 to 4 MULTIPLE-POLE & DETENT SWITCH A switch with multiple set of contacts (pole) and one actuating element 13 23 31 41 14 24 32 42 Switch with this circuit symbol means DETENT SWITCH; that is it has mechanical latching Sometimes called Rocker Switch RELAYS Serves as the foundation for building hard-wiring electrical control of automated systems (eg. automatic assembly eqt., process eqt.) Electromagnetically-actuated switch that switches contact via electrical current that produces magnetic field ADVANTAGES OF RELAYS 1. Easily adapted to various operating voltages 2. Not much affected by ambient temperature 3. Ideally infinite resistance between contacts in the off-state 4. Ideally zero resistance between contacts in on- state 5. Several independent circuits can be switched DISADVANTAGES OF RELAYS 1. Working surface of contacts wear through oxidation 2. Larger space requirements compared to transistors and thyristors 3. Noise is created during switching operation (because current generated magnetic field w/c in turn induces current to other circuits) 4. Limited switching speed (3ms to 17ms) 5. Relatively low pick-up time compared to transistors and thyristors SAMPLE CIRCUIT USING RELAY CONTROL SOLENOID An electromagnetic device used to generate magnetic field and therefore a resulting mechanical pull or push (usually linear motion) It is composed of a long thin loop of conductive wire wrapped around a magnetic core and generates a magnetic field around it when an electric current is passed through the conductive wire ADVANTAGES OF DC SOLENOIDS 1. Easily switched-on 2. Low Turn-On power 3. Low Holding power 4. Long Service Life (order of 100 million operations) 5. Silent DISADVANTAGES OF DC SOLENOIDS 1. Over-voltages can occur during cut-off 2. Arc suppression is required 3. High induced contact wear 4. Rectifier is required if only AC voltage is available 5. Longer switching time SOLENOID + VALVE = SOLENOID VALVES Uses the principle of solenoid to actuate the valve therefore changes its switching position Valves which are electrically actuated via the solenoid are called solenoid valves and pneumatic valves actuated electrically are called electropneumatic valves. Most common electropneumatic valves: 1. 2/2-Way Valve, Solenoid Actuated, Spring Returned 2. 3/2-Way Valve, Solenoid Actuated, Spring Returned 3. 3/2-Way Valve, Double Solenoid 4. 5/2-Way Valve, Solenoid Actuated, Spring Returned 5. 5/2-Way Valve, Double Solenoid 6. 5/3-Way Valve, Double Solenoid, Spring Centered SOLENOID + VALVE = SOLENOID VALVES 2/2-Way Valve, Solenoid Actuated, 3/2-Way Valve, Solenoid Actuated, 3/2-Way Valve, Double Solenoid Spring Returned Spring Returned 5/2-Way Valve, Solenoid Actuated, 5/2-Way Valve, Solenoid Actuated, Spring Returned Spring Returned 5/3-Way Valve, Double Solenoid, Spring Centered HOW SOLENOID VALVE OPERATES Two Types of Control: 1. Directly Actuated - The magnetic field of the solenoid directly pulls or pushes the magnetic contact of the valve thereby changing its switching position. 2. Pilot Actuated - The magnetic field of the solenoid indirectly controls the valve switching position but opens up another pilot line which now switches the valve position. - Advantage: - Smaller solenoid to achieve switching - Reduced power consumption - Reduced heat generation SAMPLE ELECTROPNEUMATICS CONTROL CIRCUIT ELECTRICAL CIRCUIT DIAGRAM -Electrical Circuit Diagrams are documented and standardized drawings of the electrical connections of the devices of the whole system - It doesn’t show the actual installation and mechanical locations of the devices and the actual wiring routes but it shows how the devices are being interconnected with cable lines through their various terminals - In addition it shows each devices designation codes for easy tracing and troubleshooting; and added devices information (eg. rated speed, cable diameter) - EN 61082-1:2006 is a standard for the preparation of documents for electrotechnology and defines how electrical circuit diagram of a system is drawn and documented. IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations IEC 60617 & EN 81346-2: FOR ELECTROTECHNICAL DIAGRAMS IEC 60617 contains graphical symbols for use in electrotechnical diagrams EN 81346-2 for letter designations for use industrial systems and installations SAMPLE ELECTRICAL CIRCUIT DIAGRAM- EN 61082-1 PNEUMATIC CIRCUIT DIAGRAM - Pneumatic Circuit Diagrams are documented and standardized drawings of the pneumatic tubing connections or pipe connections of the pneumatic devices of the whole system -It doesn’t show the actual installation and mechanical locations of the pneumatic devices and the actual pipe routes but it shows how the pneumatic devices are being interconnected with tubings or pipelines through their various ports - In addition it shows each pneumatic devices designation codes for easy tracing and troubleshooting; and added devices information (eg. nominal pressure, pipe diameter) - One standard for pneumatic circuit diagram is the DIN ISO 1219-2 standard. DIN ISO 1219-2 STANDARD  All components of a circuit have the same main code.  Letters are allocated in relation to the component.  Multiple components within a circuit are numbered serially  Pressure lines are designated with P and are separately serially numbered. Drives: 1A1, 2A1, 2A2,... Valves: 1V1, 1V2, 1V3, 2V1, 2V2,... Sensors: 1B1, 1B2,... Signal input: 1S1, 1S2,... Accessories and Source:0Z1, 0Z2, 1Z1,... Pressure lines: P1, P2,... SAMPLE DIN ISO 1219-2 CIRCUIT DIAGRAM  INTERPRETING & READING CONTROL SYSTEM PROBLEM REPRESENTATION & DOCUMENTATION  CONTROL SYSTEM PROBLEM REPRESENTATIONS & DOCUMENTATION - Problems, Operations and Sequence of Motion Profile of various devices in the system are to be properly represented and documented for easy comprehension and maintenance of the system -There are some commonly used problem representations and documentation:  Positional Sketch  Function Chart  GRAFCET POSITIONAL SKETCH -The positional sketch is a drawing or mechanical schematic diagram of a production installation or machine -It should be easily understandable and should include only the most important information such as the drives, actuators, machine fixtures and sensors - It shows the spatial arrangement of the components FUNCTION CHART With a function chart in accordance with DIN/EN 40719-6, the mode of operation of a control system can be graphically represented irrespective of the technology used. The function chart is used in numerous areas of automation technology for the planning and documentation of sequence control  step systems. field represents the sequential steps in numbers  a double-framed step field indicates the initial status or position of the sequence control system step field  instruction field designates the operations or actions to be carried out in the respective step transition  In the left-hand section of instruction field, a field letter of ‘N’ or ‘S’ is designated:  N means non-storing action  S means storing action  In the right-hand section, the acknowledgment instruction field for the execution of the instruction is entered (e.g. by means of a number or by specifying the relevant sensor).  The transition field represents the transition from one step to the next if its transition condition/s are met FUNCTION CHART - EXAMPLE GRAFCET (GRAphe Fonctionnel de Commande Etape Transition) Coined from the French word GRAphe Fonctionnel de Commande Etape Transition and is valid Europe-wide since 1 April 2002 Translated this means Graphic Representations of control function using steps and transitions Defined by a European standard DIN EN 60848 and as an international standard IEC 60848 The successor of the German function chart defined by DIN/EN 40719-6 which was no longer valid since 1 April 2005 The international predecessor of GRAFCET DIN EN 60848 is the first edition of the standard IEC 60848 dating back to 1988 GRAFCET STRUCTURE Each step is represented by a square with each step having one or more corresponding actions assigned An initial step is denoted by a double-frame square Only one step is active at a time Step transitions are initiated once the transition condition/s are met or true Transition conditions may be represented by a text, a boolean expression or a boolean diagram An arrow pointing upward placed on the action field denotes stored GRAFCET with ALTERNATIVE BRANCHING GRAFCET with PARALLEL BRANCHING  PART VI: SEQUENTIAL CONTROL SYSTEM  Sequence Control System This is a control system using a mandatory step by step sequence, in which the sequencing from one step to the next programmed step depends on certain conditions being satisfied. Example: 1. At the press of a pushbutton switch, cylinder A advances (step 1) 2. When cylinder A reaches its forward end position, it automatically retracts (step 2) 3. When cylinder A reaches its retract end position, cylinder B automatically advances (step 3) 4. When cylinder B reaches its forward end position, it CIRCUIT REALIZATION OF SEQUENTIAL CONTROL SYSTEM Representations – Chronological Order Cylinder 1.0 extends and lifts the box Cylinder 2.0 extends and pushes the box Cylinder 1.0 retracts, then Cylinder – Tabular2.0 retracts Form Work Step Motion of Cylinder 1.0 Motion of Cylinder 2.0 1 out - 2 - out 3 in - Representations – Vector Diagram Extension represented by 1.0 Retraction represented by 2.0 1.0 – Abbreviated Notation 2.0 Extension represented by : + 1.0 + Retraction represented by : - 2.0 + 1.0 - Representations – Motion Step Diagram 1 2 3 4 5=1 1.0 2.0  REPRESENTATION OF SEQUENCE CONTROL PROBLEMS A.) MOTION STEP / DISPLACEMENT STEP DIAGRAM Forward end 1 2 3 4 5=1 A Retract end Forward end B Retract end ELEMENTS OF A MOTION STEP DIAGRAM INPUT ELEMENTS MANUALLY OPERATED: ON / START OFF / ON / OFF INCHING STOP TOGGLE STEP MODE INPUT ELEMENTS MECHANICALLY (LS) OPERATED: ELEMENTS OF A MOTION STEP DIAGRAM OR CONDITION: SIGNAL BRANCHING: AND CONDITION:  REPRESENTATION OF SEQUENCE CONTROL PROBLEMS S1 Forward end 1 2 3 4 5=1 1S2 A 1S1 Retract end Forward end 2S2 B Retract 2S1 end  SIGNAL EDGES Every binary signal has a RISING EDGE positive and negative edge TRAILING EDGE POSITIVE EDGE (RISING EDGE) marks the moment at 1 which a change from 0 to 1 takes place ( or from OFF to ON. NEGATIVE EDGE (TRAILING EDGE) marks the moment at 0 which a change from 1 to 0 takes place (or from ON to time OFF) Representations – Tnn for the timer status (active or inactive) - shows whether the timer is active or not. It is a one- bit operand than can be set, reset or interrogated. 1 = active, 0 = inactive – TPnn for the timer preset (preset run-time) - defines the run-time of the timer given in hundredths of a second and can be in the range 0.00s to 655.35s. The operand for the timer preset is a permanent multi- bit operand and remains stored until a new preset is defined. – TWnn for the timer word (current run-time) - is a multi-bit operand and represents the current run- time of the timer. Switch-ON Delay Timer (TONnn) - allows outputs to be activated with a 1-signal after a delay time has expired. The timer preset represents the delay period. When the timer is started, the timer status TON does not become 1 until after the delay time has expired. A rising edge in the conditional part starts the timer. It starts running until the timer has expired or the condition changes to a 0-signal. 1 Status of Condition 0 Start of Status of 1 Start of timer timer Timer 0 Timer preset Switch-OFF Delay Timer (TOFFnn) - allows outputs to be deactivated with a 0-signal after a delay time has expired. When a rising edge is recognized for the condition, the timer preset is loaded into the timer word. A trailing edge starts the timer, which runs until the timer has expired or the timer is reinitialized by a rising edge for the condition. 1 Status of Condition 0 Status of 1 Start of Timer timer 0 Timer preset Pulse Timer (Tnn) - allows an output to be activated for a specified time when an input signal is present. It only reacts to the rising edge of the condition. This pulse starts the timer (Tnn=1). The timer preset is loaded into the timer and the timer starts to decrement until it reaches a value of zero, or a further edge (pulse) is detected at the conditional part, restarting the timer, or the timer is reset (Tnn=0). 1 Rising Status of edge Condition 0 Status of 1 Timer Timer preset 0 Start of timer on rising edge Representations – Counter status - Cnn - indicates whether the counter is activated or deactivated. It is a one-bit operand that can be set, reset, or interrogated. – Counter preset - CPnn - represents the end value for incremental counters and the start value for decremental counters. Ranges from 0 to 65535. – Counter Word - CWnn - is a non-permanent multibit operand and indicates the current counter status.