FOR OFFICIAL USE
Centre No.
Subject No.
Level
Paper No.
Group No.
Marker's No.
Total
Marks
[C036/SQP141]
Intermediate 2 T i m e : 2
Technological Studies
hours 30 minutes
NATIONAL
QUALIFICATIONS
Specimen Question Paper
Fill in these boxes and read what is printed below.
Full name of centre
Town
First name and initials
Surname
Date of birth
Day Month Year
Candidate number
Number of seat
1 Answer all the questions in Section A and any two questions in Section B.
2 Read every question carefully before you answer.
3 Write your answers in the spaces provided.
4 Do not write in the margins.
5 Do not sketch in ink.
6 All dimensions are given in millimetres.
7 Before leaving the examination room you must give this book to the invigilator. If you do
not, you may lose all the marks for this paper.
[C036/SQP141]
1
©
Marks
SECTION A
Attempt ALL questions
1.
The control circuit shown in Figure Q1 should switch on the motor of a cooling fan if
the temperature inside a small greenhouse rises above a specified level.
Supply
12 V
–t
M
560 Ω
0V
Figure Q1
(a)
The motor switches when the voltage (Vbe) between the base and the emitter of the
transistor reaches 0.7 V. Calculate the resistance of the thermistor for this
condition.
4
(b)
How could this circuit be modified to allow different “switch-on” temperatures,
without changing the type of thermistor used?
1
(5)
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Marks
2.
Figure Q2 shows a small hoist designed to raise loads of up to 1.5 kN. In operation,
the effort required to lift this load was found to be 350 N.
Figure Q2
Effort (input) = 350 N
Load (output) = 1.5 kN
(a)
How far does the effort (input) move when the load (output) is raised 1 m?
2
(b)
For the movement described in part (a), calculate:
(i) the energy output (the work done on the load);
2
(ii) the energy input (the work done by the effort).
2
(c)
Explain why the energy input is always greater than the energy output for
any type of machine.
2
(8)
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Marks
3.
An architect’s model for a public exhibition uses a lighting system which has two
switches and three 6 volt bulbs supplied by a 6 volt battery. The lights can be turned
on by any one of the two switches.
(a)
Give two reasons why the 6 volt bulbs should be connected in parallel rather than
in series in this lighting circuit.
1
2
2
(b)
Draw a circuit diagram to show how the bulbs and switches should be connected
to the battery so that the required specification is obtained.
5
(c)
Each bulb has a resistance of 20 Ω. Calculate the power one bulb will use when it
is on.
4
(11)
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Marks
4.
The incomplete pneumatic circuit diagram shown in Figure Q4 represents part of a
system for testing the reliability of a new type of door hinge. The piston is shown fully
instroked. The reciprocating piston rod operates the hinge (not shown) repeatedly until
it fails.
Valve A
B
Figure Q4
(a)
State the full name of valve A.
2
(b)
(c)
Valve A is to be used as a master switch to control the system. On Figure Q4
above, complete the required circuit connections.
4
A uni-directional flow restrictor is shown at point B. Put a tick against the
statement in the following list which best describes the effect of the flow restrictor
on the motion of the piston rod.
Tick one box.
It has no effect on either the instroke or the outstroke.
It slows both the instroke and the outstroke.
It slows the outstroke, but does not affect the instroke.
It slows the instroke, but does not affect the outstroke.
1
(7)
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Marks
5.
The control panel in a rally car includes a warning lamp to remind the driver and
navigator to fasten their seatbelts.
The warning lamp should operate if the ignition is switched on and a seatbelt is
unfastened.
The sensors are listed below:
(a)
Sensor A:
Driver seatbelt UNFASTENED = logic ‘1’
Sensor B:
Navigator seatbelt UNFASTENED = logic ‘1’
Sensor C:
Ignition switch ON = logic ‘1’
A solution for the specified system requires one 2-input AND gate and one
2-input OR gate. Draw a suitable logic circuit for this solution.
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Marks
5.
(continued)
(b)
A different solution for the control system, using three gates, is shown below.
Complete the truth table for this control system.
Sensor A
(D)
L
Sensor C
Output to LAMP
(E)
Sensor B
(c)
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
(D)
(E)
L
4
From the truth table in part (b), write down the Boolean expression for L.
L=
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2
(10)
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Marks
6.
A closed loop control system should contain most of the following elements.
reference signal
process
(a)
error detector
AND gate
feedback loop
feedback sensor
On the diagram below, write the names of the appropriate elements in the spaces
provided. Show the direction of feedback.
Output
6
(b)
A common example of a closed loop control system is found in a domestic central
heating system. For this example:
(i) name the feedback sensor;
(ii) what does the feedback sensor monitor?
2
(8)
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Marks
7.
The van shown in Figure Q7 is being used to transport building materials. The vehicle
has a total weight of 12.0 kN acting at point A, and the weight of the building materials
is 9.0 kN acting at point B.
3.0 m
1.3 m
0.5 m
B
A
R1
R2
Figure Q7
(a)
(b)
Draw a line diagram for this system, showing the four forces and their relative
positions.
4
Calculate the following forces:
(i) Reaction R1 acting at the front axle;
4
(ii) Reaction R2 acting at the rear axle.
3
(11)
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SECTION B
Attempt any TWO questions
8.
The diagram, Figure Q8(a), shows part of a system which separates two sizes of box on
a production line.
The size of a box is detected by two light sensors as it approaches the lift. When the
box arrives at the lift, cylinder A moves the lift to the correct level if required, and
cylinder B pushes the box onto one of the outgoing conveyors.
Boxes
in
Light sensors
Cylinder B
Lift
Cylinder A
Small
boxes
out
Large
boxes
out
Figure Q8(a)
Opposite each of the light sensors there is a light source, producing a beam which is cut
by boxes as they pass.
For clarity the light sources have not been included in the diagram.
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Marks
8.
(continued)
Figure Q8(b), below, shows a schematic diagram of the circuit.
Cylinder B
Valve 4
Solenoid 2
Valve 5
Valve 3
Valve 2
Cylinder A
Valve 1
Note:
Solenoid 1 is actuated by a
large box.
Solenoid 2 is actuated by a
small box.
(a)
Solenoid 1
Figure Q8(b)
Refer to the circuit diagram and explain how the system operates when a large
box is sensed.
When a large box is sensed approaching the lift, Solenoid 1
5
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Marks
8.
(continued)
(b)
The piston in cylinder A is 50 mm diameter. Calculate the maximum force
cylinder A can apply if the air supply pressure is 0.2 N/mm2.
(Show all working and units.)
5
(c)
The two light sensors are arranged as shown in Figure Q8(c), in order to detect the
size of a box as it approaches the lift.
Sensor 1
Sensor 2
Lift
Figure Q8(c)
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Marks
8.
(c)
(continued)
A truth table showing the control of Solenoid 1 and Solenoid 2 is also shown.
Each sensor produces a logic ‘0’ when a box passes it. Each solenoid is activated
by logic ‘1’.
Sensor 1
Sensor 2
Solenoid 1
Solenoid 2
0
0
1
0
0
1
0
0
1
0
0
1
1
1
0
0
Disallowed
(i) The second line of the truth table has been disallowed.
Why?
2
(ii) Complete the logic diagram shown below for Solenoid 2, to satisfy the
truth table.
Sensor 1
Solenoid 2
Sensor 2
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Marks
8.
(continued)
(d)
Pin-out diagrams for five different types of TTL integrated circuit are shown
below.
TTL Integrated Circuits
+Vcc
+Vcc
+Vcc
Gnd
Gnd
7400 Quadruple
2-input OR gate
7402 Quadruple 2-input
NOR gate
+Vcc
Gnd
7404 Hex INVERTER
+Vcc
Gnd
7408 Quadruple
2-input AND gate
(i)
Gnd
7400 Quadruple
2-input NAND gate
Refer to your solution in Q8(c)(ii) and select two TTL integrated circuits from
the above group that could be used to construct the circuit. Enter the
identification number of each in the spaces provided in Figure Q8(d) below.
2
+5 V
Inputs
Sensor 1
Sensor 2
+Vcc
+Vcc
I.C. no............
Output
Driver
I.C. no............
Gnd
Output
to
Solenoid
2
Gnd
OV
Figure Q8(d)
(ii)
[C036/SQP141]
Complete all the connections needed for your solution in Q8(c)(ii). Do not
show internal connection details of the integrated circuits.
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4
(20)
Marks
9.
The load/eject table of the CD-ROM drive for a computer is driven open by a motor
which runs at 600 rev/min. Details of the operating mechanism are shown in Figure Q9
below.
part of
load/eject
table
F
E
D
OPEN
CLOSE
F
E
D
motor
A
C B
belt
load/eject table
Figure Q9
Component F is attached to the load/eject table and is driven by gear E to open and
close the table.
(a)
Name the mechanism made up of components E and F.
1
(b)
Pulley A
Pulley B
10 mm diameter
25 mm diameter
Gear C
Gear D
Gear E
20 teeth
60 teeth
40 teeth
Calculate the speed of gear E, giving your answer in revolutions per second.
4
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Marks
9.
(continued)
(c)
If the pitch of the teeth on component F is 1.5 mm, calculate the linear speed of
the table as it opens. State your answer in mm/second.
2
(d)
If the table moves 120 mm as it opens, how many seconds will it take to open fully
from the closed position?
2
(e)
State one advantage of using a belt drive in this mechanism.
1
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Marks
9.
(continued)
(f)
When the load/eject table closes fully, it closes a microswitch, and lights a LED.
The part circuit is shown in Figure Q9(f).
5V
R
0V
Figure Q9(f)
When the voltage across the LED is 2.1 V, the current flowing through it is 10 mA.
Calculate the value of resistor R which will give 2.1 V across the LED.
4
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Marks
9.
(continued)
(g)
Two possible systems for opening the load/eject table are shown in the block
diagrams in Figure Q9(g).
The motor starts when an eject button is pressed and should continue to run until
the load/eject table is opened fully.
Eject
button
Latch
Motor
driver
Motor
driver
Motor
Drive
system
Load/
eject
table
Linear
motion
Motor
Drive
system
Load/
eject
table
Linear
motion
reset
System 1
Delay
Eject
button
System 2
Latch
reset
Note:
Microswitch is closed when
the load/eject table is fully
open
Micro
switch
Figure Q9(g)
(i) Name the type of control used in System 1.
1
(ii) Which of the components in System 2 is a feedback sensor?
1
(iii) In System 2, are the sensors (eject button and microswitch) analogue or digital
devices?
[C036/SQP141]
Eject button
1
Microswitch
1
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Marks
9.
(g)
(continued)
(iv)
Which of the two systems will ensure that the load/eject table opens fully
every time?
1
Give one reason why the other system may not open the load/eject table
fully.
1
(20)
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Marks
10. A hot drinks machine must heat 0.2 kg of water ready to pour into a cup. A system
designed to do this is shown in Figure Q10.
inlet
valve
Figure Q10
Heating
element
outlet
valve
(a)
Calculate the energy needed to heat 0.2 kg of water from 18 °C to 90 °C. The
specific heat capacity, C, of the water is 4190 J/(kg K).
2
(b)
The heating element shown in Figure Q10 is rated at 3 kW and is connected to a
240 V supply.
(i)
Calculate the current drawn by the heating element.
2
(ii)
From a selection of 3A, 5A or 13A, which fuse should be used to protect the
heating element?
1
Give one reason for your answer
1
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Marks
10. (continued)
(c)
(i) Calculate the time taken for the heating element to raise the temperature of
the water from 18 °C to 90 °C. State your answer in seconds.
2
(ii) The water temperature will fall after the heater has been turned off. Suggest
one way of reducing the rate at which this happens.
1
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Marks
10. (continued)
(d)
The water heater is controlled to the following specifications:
the heating element must only switch on if the water heater is full;
the heating element should switch on if the water temperature is below 80 °C;
the heating element should switch off when the water temperature reaches
90 °C;
hot water should be dispensed when the “dispense” button is pressed;
the water heater should automatically refill with water after dispensing.
The flowchart below will satisfy the specification when complete. Write down the
missing expressions (i) and (ii).
Start
fill
No
Is heater
covered with
water?
Yes
(i)
Is temperature
> 90 °C?
Yes
No
(ii)
Yes
No
Is “dispense” No
switch pressed?
Yes
empty
[C036/SQP141]
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Page twenty-two
switch heater on
4
10. (continued)
(e)
The water heater is controlled by a microcontroller which is connected to the
input and output devices shown in Figure Q10(e) via the pins indicated in the
interface table below.
INPUT
“dispense” switch (1=pressed)
“high level” sensor (1=covered)
“low level” sensor (1=covered)
Pin
7
6
5
4
3
2
1
0
OUTPUT
inlet valve
inlet valve (1=open)
outlet valve (1=open)
high level
sensor
heater
low level
sensor
outlet valve
Figure Q10(e)
The main control program calls two sub-procedures:
“empty” pours hot water into a cup when the “dispense” switch is pressed.
“fill” refills the heating system with cold water after it has emptied.
Flow charts for each sub-procedure are shown below.
“empty” sub-procedure
“fill” sub-procedure
empty
fill
open outlet
valve
open inlet
valve
No
Is heater
system
empty?
Yes
Is heater
system
full?
Yes
close outlet
valve
close inlet
valve
wait
2 seconds
return
return
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No
Marks
10. (e)
(continued)
A PBASIC listing of the empty sub-procedure is shown below.
empty:
pouring:
high 5
if pin0=1 then pouring
low 5
pause 2000
return
‘sub-procedure empty
‘
‘
‘wait 2 seconds
‘return to main program
(i) Three lines of the sub-procedure have no comment to explain their function.
Write down a comment for
if pin0=1 then pouring
‘
low 5
‘
1
1
(ii) From the flowchart given, use PBASIC to write the sub-procedure fill.
5
(20)
[END OF QUESTION PAPER]
[C036/SQP141]
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[C036/SQP141]
Intermediate 2
Technological Studies
NATIONAL
QUALIFICATIONS
Specimen Marking Instructions
[C036/SQP141]
25
©
Marks
Deduct W mark when incorrect unit stated at final answer.
1.
(a)
R1/R2 = V1/V2
1
R/560 = 11.3/0.7
1
11 ⋅ 3 × 560
0⋅7
R =
1
= 9.04 kΩ
2.
1
(5)
(b)
Change value of lower resistor, or use variable resistor.
(a)
Distance ratio = 5
1
5 × 1m = 5m
1
(b)
Output work done = force × distance
1.5 kN = 1500 N
= 1500 × 1 = 1500 J = 1.50 kJ
(i)
Input work done = 350 × 5 = 1750 J = 1.75 kJ
correct unit at answer (Nm or J)
(ii)
(c)
3.
1
(a)
Friction (or energy loss) occurs between moving parts of system, generating
heat, causing some of input energy to be lost from system.
Any 2 valid points or other appropriate statement one mark each up to (2)
1
2
1
W
2
(8)
1
In series they would not have correct operating voltage and would light dimly;
in parallel would be connected to rated voltage.
1
Three bulbs in parallel
Two switches in parallel
Switches in series with bulb network and supply
Two out of three symbols correct
Connections correct
Power = VI = V2/R
=
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1
If one bulb fails, other two will still function; in series, if one fails, all stop
working.
(b)
(c)
1
W
26
6×6
= 1⋅8 W
20
Correct equation
Substitution
Answer
Correct unit at answer (W)
Page two
1
1
1
1
1
1
1
1
1
(11)
Marks
4.
(a)
actuator
valve type
lever/lever 3/2 valve
1
1
(b)
correct air connections, 1 mark each
correct symbol for pilot air lines
Valve A
(c)
5.
(a)
1
(7)
It slows the outstroke, but has no effect on the instroke.
A
B
C
Lamp
(b)
correct symbol, 1 mark each gate
correct connections W mark each
A
B
C
(D)
(E)
L
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
1
1
0
1
1
1
0
0
0
0
0
1
0
1
1
0
1
1
1
0
0
0
0
1
1
1
1
1
1
W mark per correct row
(c) L = A.B.C + A.B.C + ABC or L = C.(A + B) W mark each correct term up to 1W marks
W mark correct operator (ie +)
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Page three
3
1
2
2
4
2
(10)
Marks
6.
(a)
feedback loop
feedback
sensor
Reference
signal
Output
Process
Error detector
1 mark for each correct answer up to six.
(b)
(i) Temp. sensor, thermistor.
1
(ii) Measures room temperature.
7. (a)
1
(8)
12.0 kN
1.2 m
9.0 kN
1.3 m
0.5 m
R2
R1
W mark for force, W mark for position, for each of four forces
(b)
6
(i) ΣMR2 = 0 (clockwise +ve) or equivalent statement.
4
1
+(R1 × 3) – (12 × 1.8) – (9 × 0.5) = 0
1
R1 = 21.6 + 4.5
1
= 8.7 kN
1
(ii) ΣFV = 0 (upwards +ve) or equivalent statement.
+ 8.7 – 12 – 9 + R2 = 0
1
1
R2 = 12 + 9 – 8.7
R2 = 12.3 kN
[C036/SQP141]
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1
(11)
Page four
Marks
8.
(a) When large box is sensed approaching
the lift, solenoid 1 actuates a 5/2 valve
(or valve 1).
This causes an outstroke of cylinder A,
(or raises the lift).
The outstroke speed is controlled by a
uni-directional flow restrictor.
A 3/2 roller-trip valve (or valve 5) is
actuated at the end of the oustroke.
This sends a pilot signal via a shuttle
valve to actuate a 5/2 valve (or valve 3).
This causes an outstroke of cylinder B,
(or pushes the box onto the conveyor).
The outstroke speed is controlled by a
uni-directional restrictor.
A 3/2 roller operated valve (or valve 4)
is actuated at the end of the oustroke.
This sends a pilot signal to both 5/2
valves.
Cylinder A instrokes (or lowers the
lift), and cylinder B instrokes.
(b) Area 2
= πd
4
Recognise valve being actuated first.
W
Note effect on correct cylinder, either as a
correctly termed cylinder movement, or as
an effect on the system’s movement.
Note that speed of movement is
controlled.
W
Note positional sensor.
W
Note that control signal passes through a
shuttle valve.
Note effect on correct cylinder, either as a
correctly termed cylinder movement, or as
an effect on the system’s movement.
Note that speed of movement is
controlled.
W
W
W
W
Note positional sensor.
W
Note that control signal passes to both 5/2
control valves.
Note that both cylinders instroke.
W
Calculation of effective csa
3
Formula and substitution
Answer with units
1
1
W
= π 50
4
= 1960 mm2
2
Force
= pressure × area
= 0.2 N/mm2 × 1960 mm2
= 392 N
[C036/SQP141]
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Marks
8.
(continued)
(c) (i) It would suggest a box floating in
mid-air, which is not possible
under normal operating conditions.
Recognition of practical absurdity.
2
Correct logic symbol.
Correct connections
1
1
(ii)
Sensor 1
Solenoid 2
Sensor 2
Correct IC selected from pin-out diagrams
provided. Numbers written onto ICs on
diagram: 2 at 1 mark each.
(d) (i) ICs required; 7404 and 7408
(ii)
Inputs
2
+5 V
Sensor 1
Sensor 2
+Vcc
+Vcc
7404
Solenoid
Driver
Circuit
7408
Gnd
Output to
Solenoid
2
Gnd
0V
Connection from sensor 2 to an inverter
input
W
Connection from inverter output to AND
gate input
W
Connection from sensor 1 to second input
of AND gate (must be gate already used
for output from inverter).
W
Connection from AND gate output to
solenoid driver circuit input
W
Connection from 5V to pin 14 on each
chip
1
Connection from 0V to pin 7 on each chip
Alternative solutions using different connections will need to be followed
through line by line.
[C036/SQP141]
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Page six
1
(20)
Marks
9.
(a) rack & pinion
Correct mechanism
1
(b) 600 rev/min ÷ 60 sec/min = 10 rev/sec
10 rev/sec × 10 mm/25 mm = 4.0 rev/sec
4.0 rev/sec × 20T/60T = 1.33 rev/sec
Speed conversion factor
Speed ratio of pulley drive*
Speed ratio of gears C&D*
Final answer with units
1
1
1
1
*(W marks for inverted speed ratios)
(c) speed
= tooth pitch × no of teeth/sec
=1.5 mm/tooth × 1.33 rev/sec × 40 teeth/rev
= 80 mm/second
(d) Time
= distance ÷ speed
= 120 mm ÷ 80 mm/second
= 1.5 seconds
Number of teeth per second
calculated.
Product of number of teeth/second
and pitch
W
Correct answers and units
1
Correct
relationship
between
distance, speed and time, stated
either explicitly or implicitly
through the correct substitution of
known values.
1
Correct answers and units
1
(e) If system jams internally or is jammed
externally, the belt will slip, preventing
damage to the electric motor due to
overloading
OR
Effective at transmitting moderate torque
over a larger shaft separation than spur
gears.
Any appropriate answer
(f) 10 mA = 0.01 A
R = V/I
= (5 V–2.1 V)/0.01 A
= 2.9 V/0.01 A
= 290 Ω
Maintaining unit consistency in
calculation
Explicit or implicit statement of
Ohms Law
Value substitution: V(1), I(W)
Answer with units
(g) (i) Open-loop control
(ii) Microswitch
(iii) digital
digital
(iv) System 2
Dust/grit may impede the free running of
the drive mechanism
OR
An external object may impede the
movement of the CD-ROM drive
OR
Delay value may not be long enough to
allow the load/eject table to be opened fully.
[C036/SQP141]
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Page seven
Correct
Correct
Correct
Correct
Correct
statement
statement
statement
statement
statement
Suitable expression
W
1
W
1
1W
1
1
1
1
1
1
1
(20)
Marks
10. (a) Eh = mC∆T = 0.2 × 4190 × (90–18) = 60.3 kJ
(b) (i) Current, I = P/V = 3000/240 = 12.5 A
(ii) 13A fuse. Smallest fuse larger than
rated current or working current.
Would blow 3A and 5A fuses instantly
because it is much larger than either
rating.
(c) (i) time
= energy required/power of supply
= 60 300 ÷ 3000
= 20.1 seconds
(ii) Use thermal insulation to cover the
walls of the container.
(d) (i) Switch heater OFF or LOW or
LOGIC 0
(ii) Is Temperature <=80 °C?
OR
Is Temperature <80 °C?
(e) (i) Appropriate response
repeat until water is at low level or
repeat if lower water sensor is still wet
Close the outlet valve
(ii) fill:
not_full:
high 6
if pin1 = 0 then not_full
low 6
return
Correct temperature difference
Correct answer and units
1
1
Conversion factor for power
Correct answer and units
1
1
Choice of correct fuse
Clear explanation for selection
1
1
Either energy conversion factor or
power conversion factor. Top and
bottom line of fraction must have
consistent units.
Correct answer and units
1
1
Identify “thermal insulation”
1
Reference to heater and correct state
2
Reference to temperature and 80 °C
2
make clear that lower fluid level
sensor line is being interrogated (W)
make clear that program loops until
condition is false (W)
1
Identify correct valve (W)
Identify that valve is closing (W)
1
open correct valve (1)
make reference to correct input (1)
indicate an appropriate loop (1)
switch same output device off (1)
return statement (1)
[END OF MARKING INSTRUCTIONS]
[C036/SQP141]
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