Instruction
- Total number of questions : 20
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Energy Audit [ Question No: 1 To 20 ] :
Match the factor with what it does.
1. Discount factor 2. Annuity factor 3. Capital recovery factor
P. Turns a present sum into annual payments Q. Turns a single future sum into a present value R. Turns a level annual stream into a present value
A project with a 500 000 investment and a present value of savings of 758 200 has a benefit-cost ratio of about
The simple payback period of a measure is the investment divided by the
Consider the following statements about lighting.
1. The lux is a lumen per square metre 2. The marked lamp wattage excludes the ballast loss 3. Colour temperature and colour rendering are the same thing
A room 10 m by 8 m requires 300 lux. With a utilisation factor of 0.5 and a maintenance factor of 0.8, the total flux needed is
The room index used to look up a utilisation factor depends on the room's
Luminous efficacy is expressed in
None of the following is a reason compressed air is expensive except
Rewinding a burnt-out motor typically
Put the steps of an indirect boiler efficiency calculation in order.
1. Compute the flue gas mass per unit of fuel 2. Measure the flue gas composition and temperature 3. Subtract the sum of the losses from a hundred per cent 4. Compute each loss in turn
Three of the following are losses accounted for in the indirect method. The exception is
An auditor finds a transformer loaded to 15 per cent of its rating. The recommendation is
A diesel generator's specific fuel consumption worsens at light load because
A site with a maximum demand of 800 kVA and an average demand of 320 kVA has a load factor of
Consider the following statements about audit instruments.
1. An averaging clamp meter reads low on a distorted current 2. An infrared thermometer needs the emissivity to be set 3. A spot reading is adequate for a varying load
A data logger is preferred to a spot reading when the quantity
An ultrasonic steam trap tester distinguishes a failed trap by
A draught gauge on a boiler is read to establish
A thermal imaging camera is preferred to a spot thermometer when the question is
The baseline of an energy performance measurement is
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Energy Audit [ Question No: 1 To 20 ] :
Match the factor with what it does.
1. Discount factor 2. Annuity factor 3. Capital recovery factor
P. Turns a present sum into annual payments Q. Turns a single future sum into a present value R. Turns a level annual stream into a present value
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: 1-Q, 2-R, 3-P
Three factors moving money between three forms. The discount factor brings a single future sum back to the present. The annuity factor brings a level annual stream back to a present value. And the capital recovery factor does the reverse of the second, spreading a present sum over the years as level payments - which is why it is the annuity factor’s reciprocal.
A project with a 500 000 investment and a present value of savings of 758 200 has a benefit-cost ratio of about
Your Answer : (Not Answered)
Correct Answer : D
Dividing the discounted benefits by the discounted costs gives 1.52, so every rupee invested returns a rupee and a half in present terms. Ranking by this ratio is the right procedure when the capital available is limited.
The simple payback period of a measure is the investment divided by the
Your Answer : (Not Answered)
Correct Answer : A
It answers the single question of how long the money is at risk, in years, and it needs no discount rate or project life. Its appeal is that anybody can compute and understand it, which is why it remains the commonest criterion in practice.
Consider the following statements about lighting.
1. The lux is a lumen per square metre 2. The marked lamp wattage excludes the ballast loss 3. Colour temperature and colour rendering are the same thing
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: 1 and 2 only are correct
Statements 1 and 2 are correct: a lux is one lumen per square metre, and the wattage marked on a lamp excludes the ballast loss, which is why circuit watts must be used. Statement 3 confuses two independent properties - colour temperature is how warm the light looks, and rendering is how truly it shows colours.
A room 10 m by 8 m requires 300 lux. With a utilisation factor of 0.5 and a maintenance factor of 0.8, the total flux needed is
Your Answer : (Not Answered)
Correct Answer : C
The area is 80 square metres, so 24 000 lumens would suffice at the working plane, and dividing by the product of the two factors, 0.4, gives 60 000 from the lamps. The two factors together double the requirement, which is why they must never be omitted.
The room index used to look up a utilisation factor depends on the room's
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: length, width and mounting height above the working plane
\[ K = \frac{L \times W}{H_m(L+W)}. \] The index expresses how tall and narrow the room is relative to its plan, since a tall narrow room loses more light to the walls before it reaches the working plane. It is used with the surface reflectances to look up the utilisation factor.
Luminous efficacy is expressed in
Your Answer : (Not Answered)
Correct Answer : C
It states how much light a lamp gives for the electricity it consumes and is therefore the single figure by which lamp families are ranked. Comparing two installations on wattage alone, without it, says nothing about the light delivered.
None of the following is a reason compressed air is expensive except
Your Answer : (Not Answered)
Correct Answer : C
The work of compression appears largely as heat that is rejected to atmosphere, which is the fundamental reason the overall efficiency is so low. Air stores very well in a receiver, tools are less efficient than electric ones, and pressure drop is a further loss rather than an impossibility.
Rewinding a burnt-out motor typically
Your Answer : (Not Answered)
Correct Answer : A
Core damage during stripping, a changed slot fill and a different winding technique each take their toll, and two or three rewinds leave a machine several points down. Comparing the cost of a rewind with a new efficient motor is a routine audit recommendation.
Put the steps of an indirect boiler efficiency calculation in order.
1. Compute the flue gas mass per unit of fuel 2. Measure the flue gas composition and temperature 3. Subtract the sum of the losses from a hundred per cent 4. Compute each loss in turn
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: 2, 1, 4, 3
Measurement comes first, because the flue gas composition is what the whole calculation rests on. The composition then gives the gas mass per unit of fuel, the mass and temperature give each loss in turn, and the losses subtracted from a hundred per cent give the efficiency. The order is forced: nothing later can be computed before the step above it.
Three of the following are losses accounted for in the indirect method. The exception is
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: the loss in the feed pump's motor
The indirect method accounts for the losses in the path from the fuel’s energy to the steam - dry flue gas, hydrogen and moisture, unburnt fuel, radiation and convection, and blowdown. The feed pump’s motor consumes electricity, not the fuel being burned, so its loss belongs to the plant’s auxiliary power account and never appears in the boiler’s heat balance.
An auditor finds a transformer loaded to 15 per cent of its rating. The recommendation is
Your Answer : (Not Answered)
Correct Answer : D
At that loading the unit pays its full iron loss to deliver very little, and the loss continues day and night. Either the load moves to another transformer or a smaller unit replaces it, and the standby capacity has to be considered before either.
A diesel generator's specific fuel consumption worsens at light load because
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: the fixed losses are spread over less output
Friction, pumping work and the alternator’s no-load losses continue whatever the load, so at light load those fixed quantities are divided by a small output and the fuel per kilowatt hour rises sharply. A set below about forty per cent load is markedly uneconomic, which is the argument for several smaller sets rather than one large one where the load varies.
A site with a maximum demand of 800 kVA and an average demand of 320 kVA has a load factor of
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: 0.40
\[ \frac{320}{800} = 0.40. \] A load factor of 0.4 means the site is drawing on average less than half its maximum demand, so it is paying for capacity it rarely uses. Improving it by shifting or staggering loads reduces the demand charge without reducing consumption at all.
Consider the following statements about audit instruments.
1. An averaging clamp meter reads low on a distorted current 2. An infrared thermometer needs the emissivity to be set 3. A spot reading is adequate for a varying load
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: 1 and 2 only are correct
Statements 1 and 2 are correct: an averaging meter is calibrated for a sine wave and under-reads a distorted current, so a true RMS instrument is needed wherever drives or electronic loads are present; and an infrared thermometer computes temperature from radiance, so the emissivity setting must match the surface. Statement 3 is wrong - a varying load needs logging over a representative period, since a spot reading captures one moment of it.
A data logger is preferred to a spot reading when the quantity
Your Answer : (Not Answered)
Correct Answer : C
A single reading of a fluctuating load is worth very little, and a week of logging reveals the night-time base load, the shift pattern and the peaks. Accuracy is a property of the instrument rather than of the logging.
An ultrasonic steam trap tester distinguishes a failed trap by
Your Answer : (Not Answered)
Correct Answer : A
A working trap discharges condensate in bursts and then closes; a failed one passes live steam continuously, and the sound is quite different. Temperature alone cannot distinguish the two, since both a working and a blowing trap are hot.
A draught gauge on a boiler is read to establish
Your Answer : (Not Answered)
Correct Answer : C
Too little draught starves the combustion of air and too much drags cold air in through every leak, so the figure bears directly on the excess air. It is measured in millimetres of water gauge, which is why a manometer suits it.
A thermal imaging camera is preferred to a spot thermometer when the question is
Your Answer : (Not Answered)
Correct Answer : C
Scanning a switchboard or a furnace wall reveals the loose joint or the failed insulation without knowing in advance where to look, which is precisely what a spot instrument cannot do. Absolute accuracy is better from a calibrated contact probe.
The baseline of an energy performance measurement is
Your Answer : (Not Answered)
Correct Answer : B
Savings are the difference between what would have been used and what was used, so the baseline must be adjusted for production, weather and any other driver that has changed. An unadjusted comparison credits the measure with changes it did not cause.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20