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Electrical drives and_controls
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- 3. ELECTRICAL DRIVE • AUNIT CONSITING OF AN • ELECTRICAL MOTOR • ENERGY TRANSMITTING SHAFT • CONTROL EQUIPMENT
- 4. DRIVE SYSTEM • COMBINATIONOF • ELECTRICAL DRIVE AND CORRESPONDING LOAD
- 5. ADVANTAGES • FEASIBLE CONTROLCHARACTERISTICS • AVAILABLE IN WIDE RANGE OF SPEED TORQUE AND POWER • HIGHER EFFICIENCY • LOWER NOISE • CLEANER OPERATION • LOW MAINTENANCE REQUIREMENTS • ELECTRIC ENERGY IS EASY TO TRANSPORT
- 6. Examples of ElectricalDrives
- 7. Ac & DcDrives
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- 9. Compression of ACand DC Drives
- 10. TYPES OF ELECTRICALDRIVES • GROUP DRIVE • INDIVIDUAL DRIVE • MULTIMOTOR DRIVE
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- 12. GROUP DRIVE DRIVE CONSISTSOF ONLY ONE ELECTRIC MOTOR WHICH DRIVES SEVERAL MACHINES ADVANTAGE • RATING OF AN ELECTRICAL DRIVE CAN BE SMALLER DISADVANTAGE • IF ELECTRIC MOTOR IS SUBJECTED TO ANY FAULT ALL THE EQUIPMENTS BECOME IDLE • APPEARANCE IS NOT GOOD • LAYOUT IS COMPLICATED • ALL SYSTEM HAS LOWER EFFICIENCY • CAUSES OF ACCIDENT
- 13. Individual Drives • Mostcommon drive. A single motor is dedicated to each load. Applications include hard disk drives, washers, dryers, fans.
- 14. INDIVIDUAL DRIVE Advantages •IF A SINGLE MOTOR IS USED TO DRIVE A SINGLE MACHINE AND ALL THE MECHANISMS BELONGING TO THE SAME MACHINE. • LAYOUT IS GOOD • IMPROVED A POWER FACTOR • AUTOMATIC CONTROL • CONTROLING A SPEED IS EASY • USER FRINDLY • RELAIBLE DRIVE DISADVANTAGE • DUE TO POWER LOSS ,THE EFFICIENCY OF SUCH DRIVE IS ALSO POOR
- 15. MULTIMOTOR DRIVE • ASEPARATE MOTOR IS PROVIDED FOR DRIVING THE SEPARATE MECHANISM • ADVANTAGES • INCREASE THE OVERALL PRODUCTIVITY
- 16. Compression of GroupDrives and Individual Drives Sr NO. Points Group Drives Individual Drives 1 Capital Cost Low High 2 Efficiency Low High 3 Flexibility Low High 4 Reliability Low High 5 Speed Not Constant Constant 6 Power factor Low Good 7 Space High Low 8 Heavy load Difficult Easy
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- 19. Components of Torque •Frictional Torque(Tf):- When any drives rotate then friction is produces so it oppose torque • Windage Torque(Tw) :- When motor rotate then it oppose a wind force • Useful Torque :Tu= Tf - Tw
- 20. Different Load Characteristic •1. Constant torque type load. • 2. Torque proportional to speed (generator type load) • 3. Torque proportional to square of the speed (fan type load) • 4. Torque inversely proportional to speed (constant power type load)
- 21. Continue.. • 1. ConstantTorque Characteristic:
- 22. Torque proportional tospeed (generator type load)
- 23. Torque proportional tosquare of the speed (fan type load)
- 24. Torque inversely proportionalto speed (constant power type load)
- 25. Different characteristics ofdc motor • DC shunt motor
- 26. Continue.. • DC seriesMotor : -
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- 31. Different types ofcharacteristics
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- 33. Elevator • A machineconsisting of an endless belt with scoops attached, used for raising grain to an upper side for storage.
- 34. Types of Elevator Elevator Hydraulic WithHole Elevator Without Hole Elevator With Rope Elevator Rope or Traction Elevator With machine elevator Geared Elevator Geared Elevator Without machine Elevator
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- 37. Advantages & Disadvantages •Cost is low • Maintenance cost is low Disadvantages • Max. speed is 1 m/s • Efficiency low • Max travel distance 18 m
- 38. Traction Elevator • GearElevator
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- 41. Advantages & Disadvantages •Low power consumption • Speed is good • Cost is low Disadvantages • Big space • Maintained is complex
- 42. Comparison Sr no DescriptionHydraulic Traction 1 Capital Cost Low High 2 Maintance Cost Low High 3 Speed Low High 4 Travel Distance Very Short Very Long 5 Consumption of energy High Low 6 Application Only For 4 to 5 floor High rise building
- 43. FACTORS AFFECTING THESELECTION OF DRIVE • LIMIT OF SPEED RANGE • EFFICIENCY • BRAKING • STARTING REQUIREMENTS • POWER FACTOR • LOAD FACTOR • AVAILABILITY OF SUPPLY • ECONOMICAL ASPECTS
- 44. SELECTION OF MOTORBASED ON LOAD VARIATION • CONTINOUS LOAD • CONTINOUS VARIABLE LOAD • PULSATING LOAD • IMPACT LOADS • SHORT TIME INTERMITTENT LOAD • SHORT TIME LOAD
- 45. CLASSES OF DUTYAND SELECTION OF RATING OF MOTOR • ONCE CYCLE OF VARIATION OF LOAD IS DUTY • CONTINOUS DUTY • CONTINOUS DUTY,VARIABLE LOAD • SHORT TIME DUTY • INTERMITTENT PERIODIC DUTY • INTERMITTENT PERIODIC DUTY WITH STARTING • INTERMITTENT PERIODIC DUTY WITH STARTING AND BRAKING
- 46. POWER LOSSES ANDHEATING OF MOTOR • COPPER LOSS • CORE LOSS • POWER LOSSES CAUSE LOCALISED HEATING AND RESPONSIBLE FOR TEMPERATURE RISE OF THE MOTOR
- 47. STEADY STATE CONDITION •FINAL TEMPERATURE RISE IS REACHED WHEN THE RATE OF PRODUCTION OF HEAT AND RATE OF HEAT DISSIPATION ARE EQUAL
- 48. CONTINOUS RATING • CONTINOUSRATING OF A MACHINE IS THAT RATING FOR WHICH THE TEMPERATURE RISE IS JUST BELOW THE PERMISSIBLE VALUE OF TEMPERATURE RISE
- 49. HEATING AND COOLINGCURVES • A SMALLER TIME CONSTANT IS OBTAINED FOR GOOD VENTILATION • THE TIME CONSTANT IS INVERSELY PROPORTIONAL TO SPECIFIC HEAT DISSIPATION • COOLING TIME CONSTANT IS THE TIME REQUIRED TO COOL THE MACHINE
- 50. SELECTION OF POWERRATING FOR DRIVE MOTORS • CONTINOUS LOAD • CONTINOUS RATING SPECIFIES THE MAXIMUM LOAD THAT THE MOTOR CAN TAKE OVER A PERIOD FOR TIME • CONTINOUS VARIABLE LOAD • CLASS OF DUTY IS SELECTED ON BASED ON AVERAGE POWER OR CURRENT
- 51. SELECTION OF MOTORFOR INDUSTRIAL APPLICATIONS • STEEL ROLLING MILLS • DC MOTOR WITH WARD LEONARD SYSTEM • AC COMMUTATOR MOTORS • ACCURATE TORQUE AND SPEED CONTROL
- 52. CRANES AND HOISTS •SERIES MOTORS • GOOD STARTING TORQUE • ELECTRIC BRAKING AT LOW SPEED IS POSSIBLE
- 53. TEXTILE INDUSTRY • MODERATESTARTING TORQUE • CONSTANT SPEED • HIGH TORQUE SQUIRREL CAGE INDUCTION MOTOR IS PREFFERED
- 54. COAL AND MINNINGINDUSTRY • COAL CUTTING OR DRILLING REQUIRES COSTANT SPEED AND HIGH STARTING TORQUE • SQUIRREL CAGE MOTORS ARE PREFFERED • CENTRIFUGAL PUMPS ARE USED IN MINNING FOR PUMPING WATER. • HIGH TORQUE SQUIRREL CAGE ARE SELECTED
- 55. IMPORTANT QUESTIONS -TWOMARKS • DRAW THE FUNCTIONAL FUNCTIONAL DIAGRAM OF AN ELECTRICAL DRIVE SYSTEM • GIVE ANY TWO FACTORS THAT INFLUENCE THE CHOICE OF ELECTRICAL DRIVES • MENTION THE USAGE OF DIFFERENT TYPES OF MOTORS WITH APPLICATION IN TEXTILE MILL • WHAT IS MEANT INTERMITTENT DUTY • LIST ANY FOUR ADVANTAGES OF ELECTRIC DRIVES
- 56. IMPORTANT QUESTIONS -TWOMARKS • WHAT IS MEANT BY ELECTRIC DRIVE • DEFINE CONTINOUS RATING OF A MOTOR • WHAT IS OVERLOAD CURRENT CAPABILITY OF MOTOR • DEFINE COOLING TIME CONSTANT OF A MACHINE • NAME ANY FOUR CLASSES OF DUTY
- 57. IMPORTANT QUESTIONS -SIXTEEN MARKS •DERIVE AN EXPRESSION FOR A THERMAL MODEL OF MOTOR FOR HEATING AND COOLING.ALSO DRAW THE HEATING AND COOLING CURVE • EXPLAIN THE DIFFERENT CLASSES OF MOTOR DUTY WITH NEAT SKETCH • EXPLAIN THE VARIOUS FACTORS INFLUENCING THE CHOICE OF ELECTRICAL DRIVE
- 58. IMPORTANT QUESTIONS -SIXTEEN MARKS •PROBLEMS DISCUSSED IN THE CLASS
- 59. COMPARISON BETWEEN ACAND DC DRIVE S.NO D.C.DRIVE A.C DRIVE 1 SPEED TORQUE CAN BE ACHIEVED EASILY IT IS NOT EASTY TO ADJUST SPEED TORQUE CURVES 2 SELF STARTING NOT SELF STARTING 3 FREQUENT MAINTENANCE IS REQUIRED LESS MAINTENANCE 4 COSTLY CHEAPER 5 RECTIFYING CIRCUIT IS NECESSARY NO NEED
- 60. FOUR QUADRANT OPERATION QUADRAN T POLARITYOF VOLTAGE POLARITY OF CURRENT NATURE OF OPERATION I POSITIVE POSITIVE FORWARD MOTORING II POSITIVE NEGATIVE FORWARD REGENERATION III NEGATIVE NEGATIVE REVERSE MOTORING IV NEGATIVE POSITIVE REVERSE REGENERATION