Electrical drives and types

1. ELECTRICAL DRIVES AND
CONTROL
BY
D.H.Shukla

2. BASIC ELEMENTS
POWER
SUPPLY
CONTROL
EQUIPME
NT
ELECTRIC
MOTOR
MECHANICAL
LOAD

3. ELECTRICAL DRIVE
• A UNIT CONSITING OF AN
• ELECTRICAL MOTOR
• ENERGY TRANSMITTING SHAFT
• CONTROL EQUIPMENT

4. DRIVE SYSTEM
• COMBINATION OF
• ELECTRICAL DRIVE AND CORRESPONDING
LOAD

5. ADVANTAGES
• FEASIBLE CONTROL CHARACTERISTICS
• 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 Electrical Drives

7. Ac & Dc Drives

8. Continue..

9. Compression of AC and DC Drives

10. TYPES OF ELECTRICAL DRIVES
• GROUP DRIVE
• INDIVIDUAL DRIVE
• MULTIMOTOR DRIVE

11. Group Drive

12. GROUP DRIVE
DRIVE CONSISTS OF 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
• Most common 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
• A SEPARATE MOTOR IS PROVIDED FOR
DRIVING THE SEPARATE MECHANISM
• ADVANTAGES
• INCREASE THE OVERALL PRODUCTIVITY

16. Compression of Group Drives 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

17. Types of Load

18. Continue..
Active Load
Passive Load

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. Constant Torque Characteristic:

22. Torque proportional to speed
(generator type load)

23. Torque proportional to square of the
speed (fan type load)

24. Torque inversely proportional to
speed (constant power type load)

25. Different characteristics of dc motor
• DC shunt motor

26. Continue..
• DC series Motor : -

27. Compound motor

28. Induction Motor

29. Double cage motor

30. Single Phase Induction Motor

31. Different types of characteristics

32. AC series Motor

33. Elevator
• A machine consisting of an endless belt with
scoops attached, used for raising grain to an
upper side for storage.

34. Types of Elevator
Elevator
Hydraulic
With Hole
Elevator
Without Hole
Elevator
With Rope
Elevator
Rope or
Traction
Elevator
With machine
elevator
Geared
Elevator
Geared
Elevator
Without
machine
Elevator

35. Hydraulic Elevator

36. Continue….

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
• Gear Elevator

39. Continue..
• Gearless Elevator

40. Continue..

41. Advantages & Disadvantages
• Low power consumption
• Speed is good
• Cost is low
Disadvantages
• Big space
• Maintained is complex

42. Comparison
Sr no Description Hydraulic 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 THE SELECTION
OF DRIVE
• LIMIT OF SPEED RANGE
• EFFICIENCY
• BRAKING
• STARTING REQUIREMENTS
• POWER FACTOR
• LOAD FACTOR
• AVAILABILITY OF SUPPLY
• ECONOMICAL ASPECTS

44. SELECTION OF MOTOR BASED ON
LOAD VARIATION
• CONTINOUS LOAD
• CONTINOUS VARIABLE LOAD
• PULSATING LOAD
• IMPACT LOADS
• SHORT TIME INTERMITTENT LOAD
• SHORT TIME LOAD

45. CLASSES OF DUTY AND 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 AND HEATING 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
• CONTINOUS RATING OF A MACHINE IS THAT
RATING FOR WHICH THE TEMPERATURE RISE
IS JUST BELOW THE PERMISSIBLE VALUE OF
TEMPERATURE RISE

49. HEATING AND COOLING CURVES
• 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 POWER RATING 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 MOTOR FOR
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
• MODERATE STARTING TORQUE
• CONSTANT SPEED
• HIGH TORQUE SQUIRREL CAGE INDUCTION
MOTOR IS PREFFERED

54. COAL AND MINNING INDUSTRY
• 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 -TWO MARKS
• 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 -TWO MARKS
• 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 AC AND 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
POLARITY OF
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