NATIONAL CERTIFICATION EXAMINATION
FOR
ENERGY MANAGERS AND ENERGY AUDITORS
PAPER – 3 : ENERGY EFFICIENCY IN ELECTRICAL UTILITIES
Duration: 3 Hrs.
Max. Marks: 150
SECTION 1: OBJECTIVE TYPE
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The overall efficiency for the coal based power plants in India ranges from -- %
a) 40 to 50 b) 52-65 c) 28-35 d) 15-25
The standard technical losses in India are around –- %
a) 17 b) 23 c) 27 d) 50
The designed power transformer’s efficiency is in the range of –
a) 96-99 % b) 80-90% c) 90-95.5% d) 92.5- 93.5%
The primary purpose of a Capacitor is to reduce –
a) power factor b) maximum demand c) voltage d) none
A.C. Motors are –
a) capacitive loads b) inductive loads c) resistive loads d) none of the above
For a given mains frequency of 50Hz and number of poles being 6, its synchronous speed is -- rpm.
a) 3000 b) 1500 c) 1000 d) 375
The actual value of stray losses of motors up to 200 HP is likely to be -- %
a) 0.5 b) 1-3 c) 5 d) 7.5
AC induction motor is a --- motor
a) synchronous b) asynchronous c) highly expensive d) none of the above
An induction motor with 4 poles operating at 50Hz, has a slip of 2%. Its actual speed will be -- rpm.
a) 1485 b) 1500 c) 1470 d) 1440
According to BIS standards, a motor will deliver its rated output, if --a) voltage variation is ± 6% and frequency variation of ± 3%
b) voltage variation is ± 10% and frequency variation is ± 5%
c) voltage variation is ± 12% and frequency variation is ± 7%
d) none of the above
The volumetric efficiency of a compressor --- with increase in altitude of place, where the
compressor is installed
a) increases b) decreases c) does not change d) none of the above
The percentage increase in power consumption of a compressor with suction side air filter and
with pressure drop across the filter of 200 mm Wc is -- %
a) 1 b) 3 c) 2.4 d) 1.6
The compressor capacity of a reciprocating type is directly proportional to --a) pressure b) volume c) speed d) all
Which of the parameter indicated below is not required to evaluate the volumetric efficiency
of the compressor?
a) FAD b) stroke length c) power d) cylinder bore diameter
Multi-step control is employed for --- compressors
a) medium b) large c) small d) none
COP of absorption refrigeration system is --a) between 4 -- 5 b) less than 1.1 c) above 1.1 d) always around 2.75
For a living room of 12 feet x 12 feet at residence, the required A/C size for comfort-
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conditions will be --- TR
a) 0.25 b) 1 to 1.5 c) 2 d) 2.5
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Cascade systems for refrigeration are preferable in the temperature range of --- 0 C
a) -5 to -10 b) 0 to 10 c) -46 to -101 d) 5 to 10
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FAD means --a) Final Air Delivery b) Free Air Delivery c) Final Air Displacement d) Forced Air
Displacement
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The other name for Roots compressor is --a) Screw compressor b) Lobe compressor c) reciprocating compressor d) none
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Which of the following is not a centrifugal fan type?
a) Vane axial b) radial c) airfoil backward d) forward curved
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The ratio of maximum to minimum flow is called ---ratio
a) turn-up b) turn-down c) up-turn d) none
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This type of control for fans gives maximum benefits from energy saving point of view:
a) inlet guide vane control b) discharge damper control c) variable pitch control d) speed
control
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Centrifugal blower rotates at -- rpm
a) 15000 b) 1500 c) 3000 d) 750
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Typical design efficiency of aerofoil fan handling clean air is ---- %
a) 40-50 b) 80-90 c) 60-70 d) 70-80
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The most efficient method of flow control in a pumping system is -a) speed control b) impeller trimming c) throttling of flow d) none
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If two similar pumps are operating in series, the --a) flow is halved b) flow is doubled c) head is doubled d) speed is halved
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In general, water pipe lines are designed with water velocity of --a) less than 1 m/s b) up to 2m/s c) more than 2 m/s d) none of the above
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Changes in impeller diameter in centrifugal forces are limited to reducing its diameter to
about --- of its maximum size
a) around 75% b) around 70% c) about 60% d) about 93%
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The laws of affinity relating to flow, head and speed are applicable too –
a) centrifugal pumps b) centrifugal compressors c) centrifugal fans d) all of these
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Better indicator of cooling tower performance is --a) approach b) range c) wet bulb temperature d) dry bulb temperature
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L / G ratio in cooling tower is the ratio of --a) length and girth b) length and gradient c) water flow rate and air mass flow rate d) none
of the above
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Nowadays, most of the end-user specification calls for the drift loss in a cooling tower to be -a) 0.01% b) 0.02% c) 0.03% d) 0.001%
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Heat release rate to the cooling tower in vapour compression refrigeration system is equal to -- Kcal per min per ton.
a) 63 b) 127 c) 220 d) 500
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Centrifugal fans used in cooling towers are of:
a) aluminium b) galvanized steel c) FRP d) none of the above
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A device that distributes and filters the light emitted from one or more lamps is --a) control gear b) luminaire c) choke d) starter
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For the same lamp output, 250 W HPMV lamp can be replaced with --a) 250W CFL b) 150W HPMV c) 150 W HPSV d) 200W GLS
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IS 3646 stipulates --- lux as minimum illuminance for non-working interiors
a) 25 b) 35 c) 20 d) 15
Color
39. rending Index for LPSV is --a) excellent b) normal c) high d) poor
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Electronic ballast saves energy up to --a) 5% b) 15% c) 20% d) 35%
Present specific fuel consumption value of DG sets used in Industries is about --- gm per KW
a) 160 b) 50 c) 20% d) 35%
The least loss in DG set is -- loss
a) alternator b) cooling water c) friction d) exhaust gas
Auxiliary power consumption of DG set at full load of its operating capacity is about --a) 1 to 2 % b) 5 to 6% c) 10 to 12% d) 15 to 20%
The starting current value of DG set should not exceed -- % of full load capacity of DG set
a) 100 b) 200 c) 150 d) 125
The largest motor HP rating that can be started with DOL starter is about --- of the KVA
rating of the DG set.
a) 15% b) 25% c) 50 % d) 75%
Typical loss in magnetic type choke for a 40W FTL will be --a) 8W b) 14W c) 20W d) 6W
VFD connected with motor provides --a) variable speed with high efficiency b) induces eddy current c) no useful function d) none
of the above
Occupancy sensors are well suited as --a) day light-based controller
b) night-based controllers
c) motor controllers
d) noise or movement detectors in a room
Amorphous transformers are –
a) cheaper b) costlier c) equal cost as that of conventional transformer d) none of the above
IPFC eliminates – problems
a) voltage b) current c) hunting d) frequency
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Section ii
(i)
(ii)
Short Descriptive Questions – 10 x 5 =50 Marks
Answer all TEN questions
Each question carries Five Marks
S-1 What are the benefits of power factor improvement?
S-2 What is the thumb rule for installing capacitor to motor terminals?
S-3 Briefly explain how the efficacy of inter and after coolers is an indicator of heat
exchange performance?
S-4 Briefly explain the alternative Refrigerants for Vapour Compression Systems.
S-5 How can the demand on a fan be minimized to save energy?
S-6 What is the effect of over-sizing of a pump?
S-7 What are the afctors affecting Cooling Tower performance?
S-8 What are the following?
a) Luminaire b) Ignitor c) Lux d) Colour rending Index e) Illuminance
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S-9 State the advantages of accepting Diesel Power Plants.
S-10 How an Occupancy Sensor serves as an Energy saver?
Section-iii: LONG DESCRIPTIVE QUESTIONS Marks: 5 x 10 =50
1. What are the components of tariff structure? Explain in detail.
2. What are the effects of harmonics on motor operation and performance?
3. Explain the simple method of capacity assessment of air compressors.
4. In an automobile industry one compressor of rated capacity of 1000 cfm is operated to
evaluate leakage quantity in the plant during a holiday when no equipment was using
compressed air. FAD test was also carried out before conducting leakage test and found that
the compressor is delivering out put of 90% of rated capacity.
The observations on leakage test are:
a) Compressor was on load for 08 minutes
b) Compressor was unloaded for 48 minutes
c) Compressor was consuming 150 kW
Evaluate
a) Free air delivery b) Specific power consumption
c)
% leakage in compressed air system d) Leakage quantity
d) Power lost due to leakage
5. Why variable torque loads offer greatest energy savings? Explain electronic methods of
speed controllers.
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