1 If a DG set fails to start, the probable cause may be [ d ]
(a) Dirty clogged air cleaner
(b) Fuel tank empty
(c) Nozzle niddle jammed
(d) All of the above
Answer : (d) All of the above
2 If a DG set starts but stop after some time, the probable cause may be [ d ]
(a) Air in fuel
(b) Fuel line choke
(c) Fuel filter choked
(d) All of the above
Answer : (d) All of the above
3 If a DG set is not gaining full speed, the probable cause may be [ d ]
(a) Fuel tank empty
(b) Governor spring broken
(c) Fuel filter dirty
(d) All of the above
Answer : (d) All of the above
4 If a DG set misses during operation, the probable cause may be [ d ]
(a) Air in fuel line
(b) Nozzle damaged
(c) Water mixed with fuel
(d) All of the above
Answer :(d) All of the above
5 If a DG set lacks power, the probable cause may be [ a ]
(a) Pump may inject insufficient quantity of fuel
(b) Poor quality of fuel
(c) Dirty cooling system
(d) All of the above
Answer : (a) Pump may inject insufficient quantity of fuel
6 If a DG set gives excessive smoke at no load, the probable cause may be [ d ]
(a) Dirty clogged air cleaner
(b) choked fuel injection hole
(c) Faulty fuel pump
(d) All of the above
Answer : (d) All of the above
7 If a DG set excessive smoke at full load, the probable cause may be [ d ]
(a) One or more cylinder not working
(b) Poor quality of oil
(c) Nozzle jammed
(d) All of the above
Answer : (d) All of the above
8 If a DG set gives out blue smoke, the probable cause may be [ d ]
(a) Worn out liner on piston
(b) Wrong graded lubricating oil
(c) Engine used after a long time
(d) All of the above
Answer : (d) All of the above
9 If a DG set gives white smoke, the probable cause may be [ a ]
(a) Water mixed with fuel
(b) Engine used after a long time
(c) Worn out liner piston
(d) All of the above
Answer : (a) Water mixed with fuel
10 If a DG set overheats, the probable cause may be [ d ]
(a) high exhaust back pressure
(b) Engine overloaded
(c) Damaged main or connecting bearings
(d) All of the above
Answer : (d) All of the above
11 If the alternator of DG set is overheats, the probable cause may be [ d ]
(a) Improper ventilation
(b) Misalignment
(c) Overloading of machine
(d) All of the above
Answer :(d) All of the above
12 If the armature of DG set overheats, the probable cause may be [ c ]
(a) Overloading
(b) Internal short circuit
(c) Both a &b
(d) None of the above
Answer :(c) Both a &b
13 The maximum rated speed for 125 kVA Cummins make DG set is [ c ]
(a) 1500 rpm
(b) 1800 rpm
(c) 2100 rpm
(d) 2500 rpm
Answer : (c) 2100 rpm
14 The oil temperature gauge of a DG set should normally read between [ a ]
(a) 82-116 deg C
(b) 90-125 deg C
(c) 100-140 deg
(d) 122-148 deg C
Answer : (a) 82-116 deg C
15 During warming up, the load should be applied gradually on a DG set until the oil temperature reaches [ b ]
(a) 40 deg C
(b) 60 degC
(c) 80 deg C
(d) 100 deg C
Answer : (b) 60 degC
16 The water temperature of DG set in operation should normally range between [ b ]
(a) 60-80 deg C
(b) 74-91 deg C
(d) 88-98 deg C
(d) 95-110 deg C
Answer : (b) 74-91 deg C
17 The pH value of the coolant in the radiator of a DG set should be maintained between [ b ]
(a) 6.5 to 8.5
(b) 8.5 to 10.5
(c) 10.5 to 12.5
(d) 12.5 to 14.5
Answer : (b) 8.5 to 10.5
18 The diesel engine should not be operated if the pH value in the radiator is less than [ b ]
(a) 6.5
(b) 8.5
(c) 10.5
(d) 12.5
Answer :(b) 8.5
19 Primary filters in the fuel system of the DG set should be cleaned at every [ c ]
(a) 150 hrs
(b) 200 hrs
(c) 250 hrs
(d) 300 hrs
Answer :(c) 250 hrs
20 Primary filters in the fuel system of the DG set should be replaced at every [ b ]
(a) 500 hrs
(b) 800 hrs
(c) 1000 hrs
(d) 1500 hrs
Answer : (b) 800 hrs
21 The secondary fuel filter of a DG set should be replaced when the fuel pressure gauge is below
(a) 10 psi
(b) 12 psi
(c) 15 psi
(d) 20 psi
Answer : (b) 12 psi
22 The exciter in a DG set is [ a ]
(a) Shunt generator
(b) Compound generator
(c) Either of a or b
(d) None of the above.
Answer : (a) Shunt generator
24. The compression ratio in diesel engines is in the range of: [ b ]
a) 10:1 to 15:1
b) 14:1 to 25:1
c) 5:1 to 10:1
d) 1:2 to 3:1
Answer :b) 14:1 to 25:1
25. Which of the following is the last step in diesel engine operation? [ d ]
a) Induction stoke
b) Compression stroke
c) Ignition stroke
d) Exhaust stroke
Answer : d) Exhaust stroke
26. The power requirement of the DG set is determined by: [ b ]
a) base load
b) Maximum load
c) Partial load
d) Zero load
Answer : b) Maximum load
27. Present specific fuel consumption value of DG sets in industries is about ____. [ c ]
a) 220 g/kWh
b) 100 g/kWh
c) 160 g/kWh
d) 50 g/kWh
Answer : c) 160 g/kWh
28. The efficiency of diesel generating set falls in the region of: [ a ]
a) 35 – 45%
b) 50 – 60%
c) 65 – 70%
d) Above 80%
Answer : a) 35 – 45%
29. Auxiliary power consumption of DG set at full load in its operating capacity is about _ [ a ]
a) 1 - 2%
b) 5 – 6%
c) 10 - 12%
d)Above 15%
Answer : a) 1 - 2%
30. The rating required for a DG set with 500 kW connected load and with diversity factor of 1.5, 80% loading and 0.8 power factor is _____
a) 520 kVA
b) 600 kVA
c) 625 kVA
d) 500 kVA
Answer : a) 520 kVA
31. The starting current value of DG set should not exceed__% of full load capacity of DG set. [ b ]
a) 100
b) 200
c) 150
d) 300
Answer : b) 200
32. The maximum permissible percentage unbalance in phase loads on DG sets is____ [ c ]
a) 5%
b) 15%
c) 10%
d) 1%
Answer : c) 10%
33. The permissible percentage overload on DG sets for 1 hour in every 12 hours of operation is____ [ c ]
a) 5%
b) 15%
c) 10%
d) 1%
Answer : c) 10%
34. Designed power factor of a DG set is generally at: [ b ]
a) 1.0
b) 0.8
c) 0.9
d) 1.1
Answer : b) 0.8
35. Lower power factor of a DG set demands_____ [ b ]
a) Lower excitation currents
b) Higher excitation currents
c) No change in excitation currents
d) None of the above
Answer :b) Higher excitation currents
36. Which of the following losses is the least in DG sets: [ d ]
a) cooling water loss
b) exhaust loss
c) frictional loss
d) alternator loss
Answer : d) alternator loss
37. The waste heat potential for a 1100 kVA set at 800 kW loading and with 480 °C exhaust gas temperature is ____
a) 4.8 lakh kCal/hr
b) 3.5 lakh kCal/hr
c) 3 lakh kCal/hr
d) 2 lakh kCal/hr
Answer : a) 4.8 lakh kCal/hr
38. Typical exit flue gas temperature of 5 MW DG set operating above 80% load is of the order of
____. [ c ]
a) 550 to 560 °C
b) 210 to 240 °C
c) 340 to 370 °C
d) 400 to 450 °C
Answer : c) 340 to 370 °C
39. The maximum back pressure allowed for DG sets is in the range of____. [ b ]
a) 100 – 200 mm WC
b) 250 – 300 mm WC
c) 400 – 500 mm WC
d) above 500 mm WC
Answer : b) 250 – 300 mm WC
40. The operating efficiency of DG set also depends on: [ d ]
a) turbo charger
b) Inlet air temperature
c) % loading
d) all the above
Answer : d) all the above
41. For a DG set, the copper losses in the alternator are proportional to the: [ b ]
a) Current delivered by the alternator
b) Square of the current delivered by the alternator
c) Square root of the current delivered by the alternator
d) None of the above
Answer : b) Square of the current delivered by the alternator
42. The jacket cooling water temperature for DG sets should be in the range of _____ [ b ]
a) 40 – 50°C
b) 30 – 40°C
c) 80 – 90°C
d) 45 – 60°C
Answer : b) 30 – 40°C
43. The main precaution to be taken care by the waste heat recovery device manufacture to prevent the problem in DG set during operation is: [ b ]
a) Temperature raises
b) Back pressure
c) Over loading of waste heat recovery tubes
d) Turbulence of exhaust gases
Answer : b) Back pressure
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