1. Match the types of Control Systems given in the left column with their
corresponding advantage/disadvantage given in the right column.
A. Advantage of closed loop control
systems
B. Advantage of open loop control
systems
C. Disadvantage of Closed loop
control system
D. Disadvantage of open loop control
system
a)
b)
c)
d)
I. Easy to implement. Needs lesser
number of components. The overall
cost is lower.
II. Easily affected by load
disturbances.
III. The control action is dependent on
the output.
IV. Implementation is more complex
and overall cost is higher.
A: III, B: IV, C: II, D: I
A: III, B: IV, C: I, D: II
A: II, B: III, C: IV, D: II
A: III, B: I, C: IV, D: II
Answer:(d)
Advantage of closed loop control system: Control action is dependent on output.
r
+
e
C(s)
u
G(s)
y
-
u  C  s e
u  C  s  r  y If there is any change in output (y) it will affect the control input (u) and
immediately takes the corrective action.
2.
Suppose a company buys two types of band saw machines for cutting steel
ingots brought in by customers to dimension namely, Manual and Automatic, taking
loan from a bank to be paid back in 24 equal monthly instalments. From figures
given below for each machine, compute the amount of profit/machine the company
can earn from each type of machine in 2 years by cutting ingots for 200
hours/month assuming enough demand such that the machines cut every day
neglecting times for maintenance.
Manual
Automatic
Cost
₹10,00,000
₹20,00,000
Manpower
6 (@₹30000/month)
2(@₹40000/month)
Average energy
consumption
( Rs10/kWh)
Rate of annual simple
interest to be applied
on the borrowed
amount
Cost of saw/month
3 kW
4 kW
20% /yr
20%/yr
₹ 10,000
₹ 30,000
3
10
₹ 1000
₹1000
Number of products
manufactured/hr
Cutting charge /ingot
a)
b)
c)
d)
Manual: ₹4,82,96,000 , Automatic: ₹4,23,68,000
Manual: ₹ 42,96,000 , Automatic: ₹8,23,68,000
Manual: ₹ 82,96,000 , Automatic: ₹4,23,68,000
Manual: ₹ 82,96,0000 , Automatic: ₹4,23,68,00
Answer:(c)
Workinghrs.
:
200hr/month
Workingmonth
:
24months
Manual
Cost of the Machine
₹ 10,00,000/-
Automatic
₹ 20,00,000/-
Salary of employees (6 × 24 × 30,000)
= ₹ 4,32,000/-
(2 × 24 × 40,000)
= ₹ 19,20,000/-
Total cost of energy
(200 × 24 × 3 × 10)
= ₹ 1,44,000/-
(200 × 24 × 4 × 10)
= ₹ 1,92,000/-
Total interest
(10,00,000 × 0.2 × 2)
= ₹ 4,00,000/-
(20,00,000 × 0.2 × 2)
= ₹ 8,00,000/-
Total cost of saw
(24 × 10,000)
= ₹ 2,40,000/-
(24 × 30,000)
= ₹ 7,20,000/-
Total cost price
₹ 61,04,000/-
₹ 56,32,000/-
Total selling price
(200 × 24 × 3 × 1000)
= ₹ 1,44,00,000/-
(200 × 24 × 10 × 1000)
= ₹ 4,80,00,000/-
Total profit
(₹ 1,44,00,000 - ₹ 61,04,000)
= ₹ 82,96,000/-
(₹4,80,00,000 - ₹ 56,32,000)
= ₹ 4,23,68,000/-
3. What type of automation system would you recommend for manufacturing
Fluorescent Tube Lights & Garments?
a) Fluorescent Tube Lights: Flexible & Garments: Fixed
b) Fluorescent Tube Lights: Programmable & Garments: Flexible
c) Fluorescent Tube Lights: Fixed & Garments: Programmable
d) Fluorescent Tube Lights: Fixed & Garments: Flexible
Answer:(d)
Fixed Automation: It is used in high volume production with dedicated equipment,
which has a fixed set of operation and designed to be efficient for this set.
Continuous flow and Discrete Mass Production systems use this automation. e.g.
Distillation Process, Conveyors, Paint Shops, Transfer lines etc.
A process using mechanized machinery to perform fixed and repetitive operations in
order to produce a high volume of similar parts.
Flexible Automation: It is used in Flexible Manufacturing Systems (FMS) which is
invariably computer controlled. Human operators give high-level commands in the
form of codes entered into computer identifying product and its location in the
sequence and the lower level changes are done automatically. Each production
machine receives settings/instructions from computer. These automatically
loads/unloads required tools and carries out their processing instructions. After
processing, products are automatically transferred to next machine. It is typically
used in job shops and batch processes where product varieties are high and job
volumes are medium to low. Such systems typically use Multi purpose CNC
machines, Automated Guided Vehicles (AGV) etc.
4.
Match the types of Production Systems in factories given in the left column
with their corresponding products given in the right column
A) Continuous Flow Process
I. Pharmaceuticals
B) Mass Manufacturing Of Discrete
Products
II. Garments
C) Batch Production
III. Steel
D) Job Shop
IV. Cycles
a)
b)
c)
d)
A: III, B: IV, C: I, D: II
A: II, B: IV, C: III, D: II
A: III, B: I, C: IV, D: II
A: IV, B: II, C: I, D: III
Answer:(a)
A) Continuous flow process: Manufactured product is in continuous quantities i.e.,
the product is not a discrete object. Moreover, for such processes, the volume of
production is generally very high, while the product variation is relatively low.
Typical examples of such processes include Oil Refineries, Iron and Steel Plants,
Cement and Chemical Plants.
B) Mass Manufacturing of Discrete Products: Products are discrete objects and
manufactured in large volumes. Product variation is very limited. Typical
examples are Appliances, Automobiles etc.
C) Batch Production: In a batch production process the product is either discrete or
continuous. However, the variation in product types is larger than in continuousflow processes. The same set of equipment is used to manufacture all the product
types. However for each batch of a given product type a distinct set of operating
parameters must be established. This set is often referred to as the “recipe” for
the batch. Typical examples here would be Pharmaceuticals, Casting Foundries,
Plastic moulding, Printing etc.
D) Job shop Production: Typically designed for manufacturing small quantities of
discrete products, which are custom built, generally according to drawings
supplied by customers. Any variation in the product can be made. Examples
include Machine Shops, Prototyping facilities etc.
5.
A,B and C are three different product manufacturing systems whose
characterisation in terms of product quantity vs product variety is shown below.
Choose the right option for automation system for A, B and C.
a)
A:
Fixed Automation System, B:
Flexible Automation System,
Programmable Automation System.
b)
A: Fixed Automation System, B: Programmable Automation System,
Flexible Automation System.
c)
A:
Fixed Automation System, B:
Flexible Automation System,
Programmable Automation System.
d)
A:
Flexible Automation System, B:
Fixed Automation System,
Programmable Automation System.
C:
C:
C:
C:
Answer: (b)
A) FixedAutomation:Itisusedinhighvolumeproductionwithdedicatedequipment,
which has a fixed set of operation and designed to be efficient for this set.
Continuous flow and Discrete Mass Production systems use this automation. e.g.
DistillationProcess,Conveyors,PaintShops,Transferlinesetc.
Aprocessusingmechanizedmachinerytoperformfixedandrepetitiveoperationsin
ordertoproduceahighvolumeofsimilarparts.
B) ProgrammableAutomation:Itisusedforachangeablesequenceofoperationand
configuration of the machines using electronic controls. However, non‐trivial
programming effort may be needed to reprogram the machine or sequence of
operations.Investmentonprogrammableequipmentisless,asproductionprocess
isnotchangedfrequently.ItistypicallyusedinBatchprocesswherejobvarietyis
lowandproductvolumeismediumtohigh,andsometimesinmassproductionalso.
e.g.inSteelRollingMills,PaperMillsetc.
C) FlexibleAutomation:ItisusedinFlexibleManufacturingSystems(FMS)whichis
invariablycomputercontrolled.Humanoperatorsgivehigh‐levelcommandsinthe
form of codes entered into computer identifying product and its location in the
sequence and the lower level changes are done automatically. Each production
machine receives settings/instructions from computer. These automatically
loads/unloads required tools and carries out their processing instructions. After
processing, products are automatically transferred to next machine. It is typically
used in job shops and batch processes where product varieties are high and job
volumes are medium to low. Such systems typically use Multi purpose CNC
machines,AutomatedGuidedVehicles(AGV)etc.
6.
Name the subsystems A, B and C of a typical sensor system shown below.
Physical
medium
A
B
C
Fig.Q6 Typical Sensor System
a) A: Sensing element, B: Signal Conditioning and Processing Element, C:
Target Signal Handling Element
b) A: Signal Conditioning and Processing Element, B: Sensing element, C:
Target Signal Handling Element
c) A: Signal Conditioning and Processing Element, B: Target Signal Handling
Element, C: Sensing element.
Answer: (a)
7.
Name the levels A and B of a typical Automation Pyramid shown below.
B
Production
control
A
Automatic control
Sensors,actuators
Fig.Q7 Typical Automation Pyramid
a) A: Enterprise Management, B: Supervisory control
b) A: Supervisory control, B: Process Control
c) A: Supervisory Control, B: Enterprise Management
Answer: (c)
8. State three major functions of the Supervisory Control Level of an Automation
System
a)
b)
c)
d)
Process Scheduling, Maintenance Management, Inventory Management.
Set point generation, Process Monitoring, Operator Interface.
Set point generation, Inventory Management, Operator Interface.
Set point generation, Maintenance Management, Inventory Management.
Answer: (b)
9.
State three major functions of a Production Control Level of an Automation
System
a)
b)
c)
d)
Process Scheduling, Maintenance Management, Inventory Management.
Set point generation, Process Monitoring, Operator Interface.
Set point generation, Inventory Management, Operator Interface.
Set point generation, Maintenance Management, Inventory Management.
Answer: (a)
10. What is the highest level of automation pyramid is present in the system shown
below
Fig. Q10: Automatic bottle filling system
a)
b)
c)
d)
Level 0
Level 3
Level 2
Level 1
Answer:(d)
Position of
valve at the tank
Reference
Weight
signal
+
Controller
Belt Driving
Mechanism
Weight sensor
Filled
bottle
11. What is the highest level of automation pyramid is present in the system shown
below
Fig Q11: Water level controller
a)
b)
c)
d)
Level 2
Level 3
Level 1
Level 0
Answer:(c)
Desired level
+
Controller
-
Pneumatic
valve
Float
position
Actual level
Tank