Ilydraulic and Pneumatic Systems

Hydraulic and Pneumatic  Systems

TWO-MARK QUESTIONS AND ANSWERS

1. Definc fluid power.

 Fluid power technology is a means to convert, transmit, control and apply fluid energy to perform useful work. Fluid power includes hydraulics and pneumatics.

பாய்ம ஆற்றல் தொழில்நுட்பம் என்பது பாய்ம ஆற்றலை மாற்றியும், கடத்தியும், கட்டுப்படுத்தியும் பயனுள்ள வேலையைச் செய்வதற்கு பயன்படுத்தும் ஒரு வழிமுறையாகும். பாய்ம சக்தியில்  hydraulics and pneumatics.அடங்கும்.

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2.Differentiate oil hydraulics and pneumatics.

Oil hydraulics employs pressurized liquid and pneumatics employs compressed air.

Oil hydraulic systems operate at pressures upto 200 bar or even much higher. Pneumatic systems operate in a pressure range of 5 to 10 bar.

Oil hydraulic systems are used in high load applications and accurate speed control or positioning is required. Pneumatic systems are used in low or medium load application and high velocities are required.

3. What is the basic law that is important in applying fluid power?

Pascal law is the basic law used in fluid power. According to Pascal law, the pressure generated at one point in a confined liquid acts equally in all directions.

4. List five fields of applications of fluid power.

Agriculture, Aviation, Fabrication industry, Machine tools, Oil industry and Pharmaceuticals.

5. Why is hydraulic power especially useful with heavy work?

Hydraulic systems generally operate at high pressures and provide high forces. So they are useful with heavy work. 

6.Where are pneumatic systems preferred? Pneumatic systems are preferred where low or medium size forces are required

and velocities are high. Because of their low cost, they are preferred in industrial automation.

7. What are the primary functions of hydraulic fluid? 

(1) Transfer fluid power efficiently. (ii) Lubricate the moving parts. (iii) Absorb, carry and transfer the heat generated within the system. Name few properties of a hydraulic fluid. (i) Viscosity

(ii) Viscosity Index : (iii) Oxidation stability

(iv) Demulsibility (v) Lubricity

(vi) Rust prevention (vii) Flash point and fire point (viii) Neutralization Number

8. What are the undesirable results when an oil viscosity is too high?

When the viscosity is too high (1) The viscous oil may not be able to pass through the pipes. (11) The working temperature will increase because there will be internal friction.

(iii) The consumption of power will increase. 

9. What are the undesirable results when an oil viscosity is too low?

When the viscosity is too low i) The internal and external leakage will increase.

(m) It cannot lubricate properly and will lead to rapid wear of the moving parts. 

10. What is Viscosity Index and Give is its significance?

The rate of change of viscosity with temperature is indicated on an arbitrary scale called Viscosity Index (VI). The lower the viscosity index, the greater the variation in viscosity with changes in temperature and vice versa. 

11. What is demulsibility?

The ability of a hydraulic fluid to seperate rapidly from moisture and successfully resist emulsification is known as demulsibility. 

12. Why should a hydraulic fluid have good lubricating ability?

If the hydraulic fluid does not have good lubricating ability it will not lubricate moving parts properly, causing wear. Wear results in increased clearence, which leads to all sorts of operational difficulties including fall of efficiency. 

13. What is neutralization number of hydraulic fluid and Give its significance?

The neutralization number is a measure of acidity or alkalinity of a hydraulic fluid. High acidity causes the oxidation rate in an oil to increase rapidly. 

14. Define the term pour point and its importance.

The teniperature at which oil will congeal is referred to as the pour point, i.e. the lowest temperature at which the oil is able to flow easily. It is of importance in cold countries where the system is exposed to very low temperatures. The pour point must be well below the minimum temperature expected in normal condition. 

15. Name three fire resistant fluids.

  i Water glycols

(ii) Water oil emulsions (iii) Phosphate esters

16. Name the basic components required in hydraulic system.

(i) Pump

(ii) Hydraulic valves 

(iii) Hydraulic actuators 

17. What is a positive displacement pump and how does it differ from a centrifugal pump? 

Positive displacement pump is a pump in which there is a physical displacement of the boundary of fluid mass. Centrifugal pump is a non-positive displacement pump. In this there is a relative motion between the fluid and rotor.

In positive displacement pump, the outlet flow is independent of system pressure. But in centrifugal pump the outlet flow is dependant on system pressure. So when pressure increases, the flow reduces.

18. What is the main advantage of hydropneumatics?

The hydropneumatic systems use air and oil. By the use of both media, the quick action of air and smooth high pressure action of oil both can be achieved. 

19. What is the function of pump in a hydraulic system?

In a hydraulic system, a pump converts mechanical energy into hydraulic energy. Mechanical energy is given to the pump via a prime mover such as an electric motor.

20. Name the three popular construction types of positive displacement pumps.

i Gear pumps

(ii) Vane pumps 

(iii) Piston pumps 

21. Name the different designs of gear pump.

i External gear pump

(ii) Internal gear pump 

(iii) Lobe pump

(iv) Screw pump 

22. Why is the operation of a screw pump quiet?

In the screw pump, the fluid does not rotate but moves linearly. Thus even at higher speed, there are no pulsations. So it is a quiet operating pump. 

23. Name the different designs of vane pump.

(1) Unbalanced vane pump (i) Balanced vane pump 

24. What is the difference between fixed displacement and variable displacement pump? In the fixed displacement pump, the pump displacement cannot be varied by any means. But in the variable displacement pump, the pump displacement can be 

varied by any arrangement. 

25. Why gear pump cannot be used as a variable displacement pump?

In the gear pump, the displacement depends on the design parameters of gears and they cannot be changed. So the displacement cannot be varied in gear pumps,

26. How can the unbalanced vane pump be used as a variable displacement pump?

In unbalanced vane pump. the displacement depends on eccentricity between rotor and cam ring. By mechanically varying the eccentricity, the pump delivery is varied.

27. What is a pressure compensated vane pump and how does it work?

In the unbalanced vane pump, the displacement can be varied by varying the eccentricity. By a compensator piston arrangement, the eccentricity is varied depending on the system pressure thereby pump delivery is varied. This pump is called pressure compensated vane pump. 

28. What is meant by a balanced design vane pump?

In balanced vane pump, there are two inlet and outlet ports which are diametrically opposite to each other. Because the pressure ports are opposite to each other, a complete hydraulic balance is achieved. 

29. Name the two basic types of piston pumps.

(1) Axial piston pump

(i) Radial piston pump 

30. How can the displacement of an axial piston pump be varied?

In axial piston pumps, by varying the stroke length the displacement can be varied. In bent axis type, by varying the angle between cylinder block and drive shaft centerline, the stroke length can be varied. In swash plate type by varying the swash plate angle the stroke length can be varied. 

31. Define volumetric efficiency of a pump. 

Volumetric efficiency of pump

= Actual flow rate produced by the pump / Theoretical flow rate the pump should produce

32. Define mechanical efficiency of a pump.

Mechanical efficiency = Theoretical power required to operate the pump  /Actual power delivered to the pump 

33. Define overall efficiency of a pump.

Overall efficiency . =Power output by the pump /Actual power input to the pump 

34. What is a hydraulic actuator?

The actuator is a hydraulic element which converts the pressure energy of the fluid into mechanical energy. 

35. What are the types of hydraulic actuators?

There are three basic types of hydraulic actuator (1) Hydraulic motor-continuous rotary motion (ii) Semi-rotary actuator-limited angle movement.(iii) Hydraulic cylinder-linear motion 

36. What is the purpose of hydraulic motor and how does it differ from the hydraulic pump. 

The motors are actuated by the fluid. The fluid forces the motor to create the rotary motion. The motor is mechanically linked to the load and develops torque. So a hydraulic motor converts hydraulic energy into mechanical energy. But a pump converts the mechanical energy into hydraulic energy. 

37. Name the construction types of hydraulic motors available.

(i) Gear type hydraulic motors (i) Vane type hydraulic motors

(iii) Piston type hydraulic motors 

38. Where are external gear motors used?

External gear motors are used when relatively high speed and low torque is needed. 

39. Define volumetric efficiency of a hydraulic motor?

Theoretical flow rate required to drive the motor /Actual flow rate into the motor 

40. Define mechanical efficiency of a hydraulic motor.

Mechnical efficiency .=- Actual power given by the motor

bol/ Theoretical power it should deliver 

41. What is a semi-rotary actuator?

Senii-rotary actuators convert pressure energy into torque, which turns through only limited angle. 

42. List few applications of semi-rotary actuator?

The semi-rotary actuators are used for lifting, tilting, opening, closing, indexing, swinging and bending applications. 

43. How is single acting cylinder retracted?

The single acting cylinder is retracted using gravity or by the inclusion of a compression spring at the rod end of single acting cylinder. 

44. What are the advantages of double acting cylinder over a single acting cylinder? 

(1) In a single acting cylinder, the fluid is fed only on one side. Hence the cylinder can produce work in one direction only. But the fluid moves the piston in two directions in a double acting cylinder, so they perform work in both directions. In a single acting cylinder, the stroke is limited by the compressed length of the spring. But in principle, the stroke is unlimited in a double acting cylinder. (III) While the piston moves forward in a single acting cylinder, the fluid has to overcome the pressure of the spring and hence some power is lost before the actual stroke of the piston starts. But this problem is not present in a double acting cylinder 

45. What is cylinder cushioning?

Due to the inertia forces of the moving parts at the end of piston travel, the piston will hit the cylinder head at full speed. To overcome this, the designers provide an arrangement by which the hydraulic cylinder can be slowly retarded or cushioned during the last portion of the stroke. This is known as cylinder cushioning. 

46. For what application, a double rod cylinder is best suited? 

The double rod cylinders are suitable when work has to be performed at either or both ends and operating speed must be equal in both directions. 

47. What is the advantage and disadvantage of tandem cylinder?

The tandem cylinder provides increased output force when the bore size of the cylinder is limited. But the length of the cylinder is more than a standard cylinder and also requires a larger flow rate to achieve a speed. 

48. What is a telescoping cylinder? When is it normally used?

A telescoping cylinder is a cylinder employing several pistons which telescope into each other. This cylinder is used where a relatively long working stroke is needed for a short cylinder length. 

49. Name the types of cylinder mountings.

(i) Fixed centerline mounts — Tie rod end -Rod end flange

Blind end flange -Centerline lugs (ii) Fixed non-centerline mounts

-End lug mounts -Side lug mounts -Integral key mounts -Flush mounts (iii) Pivoted centerline mounts -Rod end trunnion -Blind end trunnion -Cievis Center trunnion

50. What are the three important things that are controlled in a hydraulic system?

In a hydraulic system, the pressure, direction and volume of flow are controlled. The pressure is controlled to control the force. Flow is controlled to control the velocity. Direction is controlled to obtain actuator motion in both directions. 

51. What is the function of relief valve in a hydraulic system?

The function of a relief valve is to limit the system pressure to a specified maximum value by diverting the pump flow back to the tank. 

52. What are the advantages of compound relief valve over direct acting relief valve?

1) Compound relief valves are usually smaller than the simple relief valves for the same flow and pressure settings. (ii) They also have a wider range of maximum pressure setting. (iii) They can also be operated remotely by connecting a simple relief valve to

the vent port. 

53. What is the function of an unloading valve?

The unloading valve is useful to control the amount of flow at any given time in systems having more than one fixed delivery pump. 

54. What is the function of a sequence valve?

When the operation of two cylinders is required to be performed in sequence, the sequence valve is used. 

55. When is the pressure reducing valve used in a hydraulic system?

Pressure reducing valve is used to maintain reduced pressure in specified locations of hydraulic system. 

 56. Name one application of a counterbalance valve.

The counterbalance valve is used to maintain back pressure on a vertical cylinder to prevent it from falling due to gravity. 

57. What is a check valve?

The check valve is a one way valve, which allows flow in one direction on the other direction the flow is not permitted. 

58. How does a pilot operated check valve differ from a simple check valve?

Pilot operated check valve is a two way valve. This type of check valve allows free flow in one direction; it allows flow in other direction also, when a pilot pressure is applied. But simple check valve always allows flow in only one direction.

59. When are three way valves used in a hydraulic circuit?

Three way valves are used to operate single acting cylinders and two three way valves are needed to operate a double acting cylinder. 

60. What is meaant by actuation of valve? List the various actuating devices of direction control valves. 

Actuation is a method of moving valve element from one position to another. The various actuating devices are: Manually operated, Mechanically operated, Solenoid operated and Pilot operated. 

61. What is a solenoid and how does it work?

A solenoid is a electromagnetic coil. When it is energised, it creates a magnetic force that pulls the armature. The armature is connected to the spool of the direction control valve and the valve is actuated. 

62. What is meant when a flow control valve is said to be pressure compensated'?

The flow through the flow control valve varies as the square root of the pressure drop across it. So any change in pressure at the outlet and inlet changes the flow through the valve. Pressure compensated flow control adjusts automatically to pressure changes and maintains a constant pressure drop from inlet to outlet, thus provides constant flow. 

63. What is the need for temperature compensation in flow control valves?

As the viscosity of oil varies with temperature, the oil becomes less viscous when temperature increases. As the less viscous fluid flow more readily through an orifice, the increase in temperature causes increase in flow for a valve setting. So temperature compensation is needed to offset the effect of such temperature variations. 

64. Name the three ways of applying flow control valves?

The three ways of applying flow control valves are (1) Meter-in

(ii) Meter-out (iii) Bleed-off 

65. Differentiate meter-in and meter-out controls.

In meter-in type, the flow control valve is located in the pressure line leading to the work cylinder. This type is used when load characteristics are constant and positive.

In meter-out type, the flow control valve is installed in the return side of the cylinder. This type is used in machine tools like drills and mills in which the tool is dragged suddenly.

66. What is a flow divider and name the different types.

Flow divider is a flow control valve and is used to divide the fluid flow from a single source into two or more streams of equal flow.

There are two types of flow dividers: 1. Valve type

2. Motor type: 

67. What is the purpose of a deceleration valve?

The purpose of the deceleration valve is to gradually reduce the flow rate going out of the cylinder to provide deceleration of the heavy loads. 

68. What is a modular valve? 

Modular valve is a stack of control valves one on the other to form a complete valve pack. This arrangement forms a compact system, thereby reducing assembly cost and eliminates much of the interconnecting pipe work. 

69. What is a catridge valve.

Catridge valve consists of a catridge which can be mounted in a standard recess in a valve block. These valves give necessary control function such as pressure,flow and direction. 

70. What is a servo valve and what is its function?

Servo valve is a direction control valve which has infinite variable positioning capability. Thus it can control not only the direction of fluid flow but also the amount. It gives a very accurate control of position and velocity of an actuator. 

71. What is the purpose of seals in hydraulic system and how are they classificul?

The seals are used to prevent the internal and external leakages of hydraulic system. Seals may be classified as (i) Positive type (ii) Non-positive type; seals may be classified in another way as (1) Static seals (ii) Dynamic seals. 

72. State the difference between positive seals and non-positive seals.

Positive seals prevent even a small amount of leakage. Positive seals are used bor external applications such as pipe and flange joints. Non-positive seals allow small amount of fluid to pass and are used for internal applications. 

73. What is the difference between static seals and dynamic seals.

Static seals prevent leakage between non-moving parts and dynamic seals prevent leakage in moving components. 

74. List out the most widely used types of seal configurations.

Static seals-Gaskets, O-rings Dynamic seals— (i) Contact seals Lip type seals, U rings, cup seals, chevron rings, wipers and scrapers (ii) Clearence type seals-Piston rings.

75. What is the difference between a strainer and filter?

Strainer is a device for the removal of solids from a fluid wherein the resistance of motion of such solids is in a straight line.

Filter is a device for the removal of solids from a fluid wherein the resistance of motion of such solids is in a tortuous path. 

76. Name the various filter media.

(i) Woven wire cloth (ii) Paper filter (iii) Woven cloth media (iv) Sintered metal powders (v) Ceramic and plastic media 

77. List out the basic types of filtering methods used in hydraulic system.

The basic filtering methods are (1) Surface type (ii) Depth type

(iii) Edge type 

78. List the various locations where filters are installed in hydraulic systems?

(i) Suction line filter (ii) Pressure line filter (iii) Return line filter

(iv) Bypass and bleed-off filter 

79. What is an intensifier and when is it used?

An intensifier is a device which converts low pressure fluid power into high pressure fluid power. Intensifiers are used when a great force is needed for a relatively short distance. 

80. What is meant by synchronisation of cylinder motion? Name the various methods to achieve it. 

If a load is to be lifted with the help of two or more hydraulic cylinders, the cylinders are connected by some means to synchronise their motion.

The various methods are (i) Tie cylinders (ii) Series piping (iii) Synchronising with flow control valves

(iv) Synchronising with matching pumps (v) Synchronising with flow dividers. 

82. What is the purpose of regenerative circuit and how is it attained?

A regenerative circuit is used to speedup the extending speed of a double acting cylinder. This is attained by connecting the return flow from cylinder to pump flow.. 

83. What is an accumulator?

An accumulator is a device that stores potential energy of an incompressible fluid held under pressure by an external source against some dynamic force. The dynamic force can come from source like gravity, mechanical or compressed gas.

84. Name the three basic types of accumulators used in hydraulic system.

(1) Weight loaded type (ii) Spring loaded type

(iii) Gas loaded type 

85. State the various functions of accumulator in hydraulic circuit?

Leakage compensation, auxiliary power source, emergency power source, shock suppressor, thermal expansion compensator 

86. What is a hydrostatic drive?

A hydrostatic drive consists of sitive displacement pump, driving a positive displacement hydraulic motor,

87. What is the difference between open-loop and closed-loop hydrostatic transmission? 

In open-loop transmission, all the fluid discharged by the motor returns to the oil reservoir. In closed-loop transmission the fluid flows in a continuous path from the pump outlet port to the hydraulic motor inlet port and then directly back to

the inlet of the pump 

88. What are the three basic arrangements in hydrostatic drives?

(1) Variable displacement pump, fixed displacement motor-constant torquetransmission (ii) Fixed displacement pump, variable displacement motor—constant power transmission (iii) Variable displacement pump, variable displacement motor—variable torque,

variable power transmission. 

89. What are the two braking systems used in hydrostatic drives?

The two braking systems used in hydrostatic drives are regenerative and dynamic braking. 

90. What do you understand by the term power pack?

Power pack consists of a pump, electric motor, reservoir and associated valving assembled to one unit to supply pressurised fluid. They are relatively small in size and provide functions of pressure, direction and flow control within the basic package. 101. 

91 What are the main criteria in the design of hydraulic system?

(i) Simplicity (ii) Reliability (iii) Efficiency (iv) Cost effectiveness(v) Maintainability (vi) Safety 

92. List the parameters related to the selection of hydraulic cylinders?

(1) Purpose (ii) Stroke requirement (iii) Thrust (iv) Speed (v) Acceleration and deceleration (vi) Cylinder mountings (vii) Special seal requirement. 

93. What is the purpose of stop tube in a hydraulic cylinder?

In cases, where the cylinder is rigidly fixed or pivoted at both ends, there is a possibility for excessive loading to occur. The effect of side loading can be reduced by a stop tube inside the cylinder. 

94. What is cracking pressure of relief valve and how does it affect the selection of relief valve? 

The pressure at which the relief valve opens is called the cracking pressure. The relief valve with a higher cracking pressure is selected because once the relief valve cracks, the flow is lost over the relief valve even when the system has not

yet achieved the maximum system pressure. 

95. Which type of flow control valve is preferrable, if load on the actuator undergo changes? 

Pressure compensated flow control valve is selected, if load on the actuator undergo changes.

 96. What is the difference between hydraulic tubing and hoses?

Tubes are constructed of cold drawn steel and they are used where high pressures are encountered. Hose is madeup of rubber or thermoplastic tube reinforced with steel wire or textile braiding. Hoses are used for medium pressure applications and moving machine members, 

97. List the parameters affecting the selection of a pump.

Maximum operating pressure, maximum delivery, pump drive speed, type of fluid, fluid contamination, pump pulsation, pump noise, size and weight of pump, efficiency and cost. 

98. What is the purpose of baffle plate in a fluid reservoir?

The baffle plate is provided between the pump's inlet and return lines for preventing the continuous recirculation of the same fluid into the system. So the foreign particles from the returning fluid are allowed to settle down without any disturbance and the trapped air is allowed to escape. 

99. What is an air breather in a fluid reservoir?

As the fluid level in the tank goes up and down during the various operations, a hole is provided at the top, for the inlet and exit of air and is known as air breather. 

100. What are the main functions of a fluid reservoir?

The functions are (i) to provide a chamber in which any change in volume of the fluid in the hydraulic circuit can be accomodated. (ii) to provide a radiating surface for allowing the fluid to cool. (iii) to provide a volume of fluid to allow cntrapped air to separate and leavy contaminants to settle. 

101. When is pneumatics preferred over hydraulics?

Pneumatics is preferred, over hydraulics when high speed and lower forces are required and do not require high precision. 

102. Name the three types of positive displacement compressors that are commonly

used in industry.. (1) Reciprocating piston type (ii) Rotary vane type (iii) Rotary screw type 

103. What is a multistage compressor?

A compressor that draws in air and compress it to its final pressure in two or more stages is called multistage compressor. 

104. What is the purpose of a dryer?

The purpose of the dryer is to reduce the relative humidity and dew point of the compressed air from the compressor. 

105. What is the function of an air filter?

The function of an air filter is to remove contaminants froin air before it reaches the pneumatic components such as valves and actuators. 

106. What is the purpose of a pressure regulator?

The purpose of the pressure regulator is to regulate the incoming pressure to the desired pressure. 

107. Why should a lubricator be used in a pneumatic system?

Air is not a good lubricant. So to lubricate the moving parts in the pneumatic system, a fine mist of oil is discharged into the air by a lubricator. 

108. What is an F-R-L unit and give the graphic symbol of it?

F-R-L unit is a combined unit of Filter-Regulator-Lubricator.

109. What is the need for mufllers?

The use of exhausted air in industries has created noise problems. This air generates high intensity sound energy, which causes fatigue to an operator: The mufller is used to reduce the energy of exhausted air, thereby reducing the noise. 

110. What is the purpose of a shuttle valve?

The shuttle valve delivers an output when one input is present or when both are present. 

111. What is the purpose of a two-pressure valve?

The two-pressure valve delivers an output when both input signals are present. 

112. State the difference between quick exhaust valve and flow control valve.

The flow control valve is used to reduce the actuator speed from its normal speed. But quick exhaust valve accelerates the speed of the actuator. 

113. Why air cylinders cannot be used for precise speed control?

Due to the compressibility charecteristic of air, the air cylinder tends to slow down on meeting increase in load and to accelerate when the load suddenly decreases. So air cylinders cannot be employed for precise control. 

114. Classify the pneumatic cylinders based on principle.

(1) Single acting cylinder (ii) Double acting cylinder (in) Tandem cylinder (iv) Three position cylinder (v) Through rod cylinder (vi) Adjustable stroke cylinder (vii) Telescoping cylinder 

115. Name the different types of air motors

(i) Piston type motors-Axial, Radial (ii) Vane type motors—Non-reversible, Reversible (i) Turbine motors 

116. Mention few advantages of air motor over electric motor.

(i) Air motors do not require electrical power. So they can be used in volatile atmospheres. (i) Air motors can stall under full load for indefinite periods of time, while electric motors will be damaged by heat generation when stalled. (iii) Air motor speed can be regulated through simple flow control valve instead of expensive and complicated electronic speed controls. 

117. Where are suction cups used?

Suction cups can be used to pickup and hold workpieces with smooth and impervious surfaces. They are commonly used in pick and place application in industries like glass, TV, printing, sheet handling, packaging etc.

108. Define the terms running torque, starting torque and stall torque of an air motor,

The torque generated when the motor is rotating at a particular speed is running torque'. The maximum torque the motor can produce when starting under load is starting torque'. The torque required to stop the motor at a particular supply

pressure is 'stall torque'. 

109. What are the important requirement to get a maximum trouble-free life from fluid power systems? 

(i) Properly installed equipments (ii) Properly trained personnel (iii) Planned bolts preventive maintenance

(iv) Effective troubleshooting 

. 110. List five things that can cause a noisy pump.

(i) Misalignment of pump and prime mover (ii) Air remains in pump casing (ii) Pump bolts very loose (iv) Very high viscosity of oil (v) Pump running too fast 

111. List three causes for low or erratic pressure in a hydraulic system.

i Very low relief valve setting (ii) Leakage of pump delivery within the system (iii) Pump slipping its entire volume 

112. If a pneumatic cylinder has erratic motion, name the causes.

(1) Valve sticking or binding

(in) Cylinder sticking or binding 

113. What is a tree-branching chart?

Tree-branching chart is a chart used to simplify the troubleshooting process. This chart asks a question which has only two possible answers-Yes or No. The answer determines the next step to be taken in fault analysis. This chart helps to develop a logical and rapid approach to fault diagnosis. 

114. Define Low-Cost Automation and what are its features?

Low-cost automation is defined as a technology that creates some degree of automaticn around the existing equipment, tools and methods, using mostly the standard equipment available in the market. The features of LCA are (1) The automation of small to medium scale industries can be made viable. (ii) Since it is built using the existing resources, in a systematic way, the

investment risks are low. (iii) Labour productivity can be enhanced substantially.