WorksheetsDDCMT2
Total questions: 80
Worksheet time: 40mins
Name
Class
Date
1.
how many parts are used in the design of the machine?
a)
2
b)
4
c)
6
d)
5
2.
how many limitation are present in the design of the machine?
a)
3
b)
5
c)
7
d)
9
3.
how does the saturation levels limit the design?
a)
saturation level decrease the flux density
b)
saturation level increse the flux density
c)
saturation levelsprovide no flux density
d)
saturation levels provide very high flux density
4.
how many types of stresses are present in the machine?
a)
1
b)
3
c)
5
d)
2
5.
how many design problems are present according to the modern trends in the design of electrical machine?
a)
1
b)
3
c)
5
d)
2
6.
what is the relationship between efficiency and operating costs?
a)
efficiency is directly proportionan to the square of the operating cost
b)
efficiency is directly proportionan to operating cost
c)
efficiency is inverse proportion to the operating costs
d)
efficiency is inverse proportion to the square of the operating costs
7.
the mechanical parts design is very much important in which type of machines?
a)
low speed machines
b)
high speed machines
c)
medium speed machine
d)
static machine
8.
wha are the factors which are considered when the optimal solution involves iterations where in the values of variable are changed?
a)
performance
b)
cost constaint
c)
performance or cost constraint
d)
performance and cost constraint
9.
what is the basic property of electrically conducting materials?
a)
allows the passage of current through the materials
b)
storage of current in the materials
c)
leaks the current through the materials
d)
reverse the direction of current in the materials
10.
what is the correct classification of the conducting materials?
a)
low resistivity,low conductivity
b)
low resistivity,high conductivity
c)
high resistivity,high conductvity
d)
medium resistivity, medium conductivity
11.
example of low resistivity material is
a)
silver
b)
manganese
c)
magnesium
d)
tungsten
12.
example of high resistivity material is
a)
copper
b)
gold
c)
aluminum
d)
carbon
13.
low conductivity material are used for
a)
heating device
b)
thermocoples
c)
resister
d)
all of the above
14.
high conductivity materials are used in
a)
windings of electrical machine
b)
insulating materials
c)
potential dividers
d)
all of the these
15.
what materials are used as conductors in the transmission and distribution sector?
a)
copper
b)
silver
c)
tungsten
d)
aluminum
16.
what are the properties of conducting materials with respect to thre temperature coefficient of resistance and tensile strength?
a)
low temperature coefficient ,low tensile strength
b)
low temperature coefficient ,high tensile strength
c)
high temperature coefficient ,low tensile strength
d)
high temperature coefficient ,high tensile strength
17.
how should the conducting materials be in terms of malleability and ductility?
a)
highly malleable,less ductile
b)
less malleable, less ductile
c)
highly malleable, highly ductile
d)
less malleable, highly ductile
18.
which material has the highst conductivity of all materials?
a)
silver
b)
copper
c)
aluminum
d)
tungsten
19.
what should be the characteristics of high conductivity materials based on cost and flexibility?
a)
low cost,low flexibibility
b)
low cost, high flexibibility
c)
high cost,low flexibibility
d)
high cost, high flexibibility
20.
what is the temperature coefficient of silver?
a)
0.337% per c
b)
0.393% per c
c)
0.400% per c
d)
0.800% per c
21.
what does the permissible current density depends upon?
a)
local heating
b)
efficiency
c)
output power
d)
local heating and efficiency
22.
what is the relationship between temperature and the current density?
a)
current density is directly proportional to the temperature
b)
current density is directly proportional to the sqare of the temperature
c)
current density is inversely proportional to the sqare of the temperature
d)
current density is inversely proportional to the temperature
23.
what is the range of current density for small and medium power transformer?
a)
1 to 2A PER MM2
b)
1 to 2.5A PER MM2
c)
1.1 to 2.2A PER MM2
d)
1.1 to 2.3A PER MM2
24.
what id the range of current density for a large power transformer?
a)
1.5 to 2.6A per mm2
b)
2.4 to 3.4 A per mm2
c)
5.4 to 6.3 A per mm2
d)
6 to 8A per mm2
25.
what is the condition for the minimum loss condition?
a)
current density in primary< current density in secondary
b)
current density in primary>current density in secondary
c)
current density in primary= current density in secondary
d)
current density in primary>= current density in secondary
26.
what is the relationship between current density in practical transformer?
a)
current density in outer winding <current density in inner winding
b)
current density in outer winding >current density in inner winding
c)
current density in outer winding =current density in inner winding
d)
none of this
27.
the current density in relatively hv winding is made ----percentage than lv windings?
a)
1
b)
5
c)
10
d)
13
28.
leakage reactance of the transformer depeds on
a)
distance between adjacent limbs
b)
the cross section area of core
c)
the cross-section area of winding
d)
all of these
29.
which kind of arrangement leads to a low value of leakage reactance?
a)
window-more height,less width
b)
window-less height,more width
c)
window-same height&width
d)
no matter whatever the height &width of window
30.
the selection of window area depends upon the…..and…….. .
a)
total conductor area,window space factore
b)
cross-section area of core, window space factor
c)
cross-section area of core,cross -section area of yoke
d)
none of these
31.
the ratio of height to width of window is selected between…. To achive the suitable arrangement of windingheight and width
a)
1 to 2
b)
2 to 3
c)
2 to 4
d)
1.5 to 3
32.
window space factor will …….with increase in KV rating
a)
increase
b)
decrease
c)
remain the same
d)
can't say anything, need other rating
33.
what is the formula for the height of the window?
a)
height of window=area of window* width of the window
b)
height of window=area of window+ width of the window
c)
height of window=area of window- width of the window
d)
height of window=area of window/ width of the window
34.
what is the window space factor?
a)
window space factor=copper area in the window-total window area
b)
window space factor=copper area in the window+total window area
c)
window space factor=copper area in the window*total window area
d)
window space factor=copper area in the window/total window area
35.
what does the window space factor depend on?
a)
it depends on the core
b)
it depends on the armature
c)
it depends on the insulation
d)
it depends on the insulation and copper
36.
what does the insulation and copper of the transformer depend on?
a)
current rating
b)
voltage rating
c)
out power
d)
voltage rating and output power
37.
what is the empirical value of the window space factor, given the output is 2MVA and 1000KV?
a)
0.008
b)
0.01
c)
0.012
d)
0.014
38.
what is the relationship of the space factor value with the large and small outputs?
a)
small value for both large and small outputs
b)
large value for both large and small outputs
c)
large value for small outputand small value for large outputs
d)
small value for small outputand large value for large outputs
39.
what is the stacking factor?
a)
the allowance made for the power loss
b)
the allowance made for the space loss between lamination
c)
the allowance made for the heat loss between laminations
d)
the allowance made for the power loss between laminations
40.
what is the utilization factor?
a)
utilization factor =cross sectional area+gross area of the core
b)
utilization factor =cross sectional area-gross area of the core
c)
utilization factor =cross sectional area*gross area of the core
d)
utilization factor =cross sectional area/gross area of the core
41.
what is the optimum number of steps for small and large transformer?
a)
1 and 5
b)
3 and 10
c)
5 and 15
d)
6 and 15
42.
what happens if the utilization factor gets improved?
a)
core area increases and the volt/turns decreases
b)
core area increases and the volt/turns increases
c)
core area decreases and the volt/turns decreases
d)
core area decreases and the volt/turns increases
43.
how many types of cores are available for the core type transformer?
a)
2
b)
3
c)
4
d)
5
44.
what type of core section is used for shell type transformer?
a)
rectangular
b)
square
c)
stepped
d)
cruciform
45.
what is the range of the ratio of depth to width of core in the rectangular core?
a)
1 to 2
b)
1.5 to 2.5
c)
1.4 to 2
d)
1.5 to 2
46.
when square and stepped cores used?
a)
when circular coils are reqired for low voltage distribution
b)
when rectangular coils are reqired for low voltage distribution
c)
when circular coils are reqired for high voltage distribution
d)
when rectangular coils are reqired for high voltage distribution
47.
what is the ratio of the netcore area to the area of the circumscribing circle in square cores?
a)
0.58
b)
0.71
c)
0.75
d)
0.78
48.
what is the value of the ratio of gross core area to the area of circumscribing circle in cruciform cores?
a)
0.64
b)
0.79
c)
0.84
d)
0.87
49.
what is the net core area for three stepped transformer?
a)
0.45
b)
0.56
c)
0.6
d)
0.62
50.
the lamination are manufactured in a standard size to minimize the wastage of steel during punching of laminations?
a)
true
b)
false
c)
not have any relation
d)
can't say anything from one parameter
51.
how many parameters are required while defining the lenth (L)and the diameter (D)of the DC machine?
a)
2
b)
4
c)
6
d)
3
52.
what are the usual range and design limit of the peripheral speed in the dc machine?
a)
15 to 50 m/s and 15 m/s
b)
15 to 50 m/s and 30 m/s
c)
15 to 50 m/s and 45 m/s
d)
15 to 50 m/s and 37m/s
53.
for the fixed value of peripheral speed,what changes we need to do if we want to increase speed on the machine?
a)
decrease the length
b)
decrease the diameter
c)
increase the length
d)
increase the diameter
54.
what if we exceed the maximum value of the peripheral speed?
a)
cooling of machine increase
b)
overhang bands fly out
c)
frequency and iron loss will increase
d)
all of these
55.
what id the l/t ratio?
a)
pole length/pole pitch
b)
pole length/torque
c)
pole length/ peripheral speed
d)
pole length/ time constant
56.
what is the formula of the core length?
a)
core length=pole length*pole pitch
b)
core length=pole length/pole pitch
c)
core length=pole length+pole pitch
d)
core length=pole length-pole pitch
57.
what is the range of the ratio of the pole length to the pole pitch?
a)
0.56 to 0.80
b)
0.60 to 0.70
c)
0.64 to 0.72
d)
0.65 to 0.75
58.
what is the pratical range of the ratio of the pole length to the pole pitch?
a)
0.60 to 0.70
b)
0.60 to 0.70
c)
0.80 to 0.90
d)
0.70 to 0.90
59.
length of armature in limit by which of the following parameter?
a)
voltage between adjacent commutator segment
b)
moment of inertia
c)
nos of pole
d)
noe of these
60.
what is the maximum value of voltage between adjacent commutator segments?
a)
5V
b)
15V
c)
30V
d)
23.5V
61.
a large diameter designed for DC machine is required for the…….
a)
impact load application
b)
control system application
c)
fan load application
d)
none of these
62.
what is the factor which is by modern motors which are into a series of standard frames?
a)
current rating
b)
voltage rating
c)
power rating
d)
output rating
63.
how can the variation in ratings be obtained?
a)
alternative winding
b)
alternative core lengths
c)
alternative pole pitch
d)
alternative pole length
64.
what is the work of the frame of dc machines?
a)
to reduce the voltage
b)
to reduce the flux
c)
to carry the flux
d)
to carry the current
65.
a suitable number of the pole is must reuire for approprite selection of……
a)
specific electric loading
b)
specific magnetic loading
c)
for both specific electric and magnetic loading
d)
none of these
66.
how many consideration are pressent in the selection of the number of poles?
a)
2
b)
4
c)
6
d)
7
67.
what is the formula for the freuency of flux reversal?
a)
f=p/n
b)
f=p*n
c)
f=p*n/2
d)
f=n/p
68.
what happen to iron losses if we select a high number of poles?
a)
iron losses increase
b)
iron losses decrease
c)
iron losses remain the same
d)
none of these
69.
what is the design range of frequency during the selection of the number of poles?
a)
1 to 25hz
b)
25 to 50hz
c)
50 to 75 hz
d)
15 to 40hz
70.
what happen to the length of the commutators with the increase in the number of poles?
a)
increased
b)
decreased
c)
remain the same
d)
none of these
71.
what happens to the labour charges when there is an increase in the number of poles?
a)
increased
b)
decreased
c)
remain the same
d)
none of these
72.
what is the effect of the distortion of field from with respect to the small number of poles?
a)
a small number of poles cause no distoortions
b)
a small number of poles clear all distortions
c)
a small number of poles reduces distortions
d)
a small number of poles increases distortions
73.
with increase in the number of poles ,which of the following things will reduce?
a)
field mmf
b)
weight of iron
c)
overall diameter
d)
all of these
74.
with an increase in the number of poles,what happen to flashover between brushes?
a)
increased
b)
decreased
c)
remain the same
d)
none of these
75.
which of the following is considered as a design aspect of pole for DC machine?
a)
pole height
b)
pole cross-section area
c)
field winding
d)
all of these
76.
what is the flux in the pole body ,given leakage coefficient =1.25 and the useful flux per poles is 12 weber?
a)
15
b)
10
c)
0.15
d)
0.1
77.
what is the design range of leakage coefficient in the pole design of the dc machine?
a)
1 to 2
b)
1.1 to 2.2
c)
1.1 to 1.25
d)
1.1 to 3.3
78.
what is the meaning of useful flux?
a)
the flux which is being created in the machine
b)
the flux which can used
c)
the flux which can produce the output
d)
the flux that is wasted
79.
what is the range of leakage coefficient for output of 100kw?
a)
1.12-1.25
b)
1.11-1.22
c)
1.10-1.20
d)
1.11-1.15
80.
what is the range of the flux density in the pole shrank for laminated poles?
a)
1.1-1.7wb per m2
b)
1.2-1.6wb per m2
c)
1.3-1.7wb per m2
d)
1.2-1.7wb per m2
100 %
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