Question is ⇒ In general, the ratio of core length to pole pitch, in an induction motor, lies between ____ depending upon the size of the machine and the characteristics desired, Options are ⇒ (A) 0.1 and 0.3, (B) 0.4 and 1.0, (C) 0.6 and 2.0, (D) 0.7 and 3.0, (E) , Leave your comments or Download question paper.

Question is ⇒ In general, the ratio of core length to pole pitch, in an induction motor, lies between ____ depending upon the size of the machine and the characteristics desired, Options are ⇒ (A) 0.1 and 0.3, (B) 0.4 and 1.0, (C) 0.6 and 2.0, (D) 0.7 and 3.0, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	In general, the ratio of core length to pole pitch, in an induction motor, lies between ____ depending upon the size of the machine and the characteristics desired
A.	0.1 and 0.3 [Wrong Answer]
B.	0.4 and 1.0 [Wrong Answer]
C.	0.6 and 2.0 [Correct Answer]
D.	0.7 and 3.0 [Wrong Answer]
View Answer 4 -2 Explanation:- Answer : C Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

Previous question Next question

Also Read Similar Questions Below :

⇒ Which of the following is an advantage of hydrogen cooling ?
Increase in efficiency
Increase in rating
Increase in life
Smaller size of coolers

⇒ Cylindrical windings using circular conductors, employed in transformers, are
single layered
double layered
multi-layered
none of the above

⇒ In induction motors, the length of air gap in kept as small as mecha.nically possible is order to have
low power factor
high power factor
high over load capacity
any of the above

⇒ Current density in the rotor bars of an induction motor may be taken between
1.5 to 2.5 A/mm²
3 to 4 A/mm²
4 to 7 A/mm²
8 to 10 A/mm²

⇒ ____ are always double layer type.
Closed windings
Open windings
Either of the above
None of the above

⇒ Electrical machines having power outputs ranging from a few kW upto approxiuoriately 250 kW may be classified as ___
small size machines
medium size machines
large size machines
any of the above

⇒ In general, the ratio of core length to pole pitch, in an induction motor, lies between ____ depending upon the size of the machine and the characteristics desired
0.1 and 0.3
0.4 and 1.0
0.6 and 2.0
0.7 and 3.0

⇒ Which of the following factors should be considered when estimating the length of air gap ?
Power factor & Over-load capacity
Pulsation loss
Cooling
Unbalanced magnetic pull and noise

⇒ The weight of copper of both armature and field windings decreases with in number of poles.
increase
decrease
either of the above
none of the above

⇒ The flash point of transformer oil should be higher than
40°C
60°C
80°C
104°C

⇒ In D.C. machines the number of slots per pole usually lies
between 2 to 4
between 6 to 8
between 9 to 16
between 20 to 30

⇒ A current density of ____ is used for large power transformers with forced circulation of oil or with water cooling coils
1.5 to 2.5 A/mm²
3.5 to 4.5 A/mm²
4.0 to 5.0 A/mm²
5.4 to 6.2 A/mm²

⇒ The slot leakage can be calculated by making which of the following assumptions ?
The current in the slot conductors is uniformly distributed over their cross-section
The leakage path is straight across the slot and around the iron at the bottom
The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero
All of the above

⇒ A synchronous machine with large length of air gap vvill have
lower limit of stability
higher value of inherent regulation
higher noise level
smaller unbalanced magnetic pull

⇒ The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
Conduction
Convection
Radiation
All of the above

⇒ Hot rolled sheets have ____ value of permeability
zero
low
high
none of the above

⇒ The higher commutator peripheral speeds
generally lead to commutation difficulties
always lead to commutation difficulties
never lead to commutation difficulties
any of the above

⇒ The noise produced by a ____ cooled machine is less as the rotor moves in a medium of smaller density.
air
hydrogen
either (a) or (b)
none of the above

⇒ The slip rings for wound rotor machines are made of
either brass or phosphor bronze
mild steel
cast iron
chromium steel

⇒ In direct cooled system using hydrogen both stator and rotor conductors are made
solid
hollow
perforated
any of the above

⇒ In case of phase wound induction motors the full load rotor m.m.f. is taken as ____ of stator in.m.f.
40 percent
60 percent
85 percent
95 percent

⇒ A semi-enclosed slot gives
a better overload capacity
low power factor
less noise
none of the above

⇒ A practical formula for determining the thickness of insulation between low voltage and high voltage windings is
1 + 0.2 kV mm
2 + 0.5 kV ram
4 + 0.7 kV aim
5 + 0.9 kV ram

⇒ Helical windings are used in
distribution transformers
power transformers
shell type transformers
none of the above

⇒ Hydrogen has a heat transfer co-efficient ____ times that of air
1.5
2.5
3.5
4.5

⇒ Which of the following is the commonly used type of electroinagnets ?
Flat-faced armature type
Horse shoe type
Flat-faced plunger type
All of the above

⇒ In a D.C. machine the number of brush arms ____ is the number of poles.
less than
equal to
greater than
none of the above

⇒ The usual values of inaxinaum flux densities for distribution transformers using hot rolled silicon steel are
0.5 to 0.8 Wb/m²
0.8 to 1.0 Wb/m²
1.1 to 1.35 Wb/m²
1.4 to 1.8 Wb/m²

⇒ Which of the following methods is most accu rate ?
Equivalent current method
Equivalent power method
Equivalent torque method
Method of average losses

⇒ With direct water cooling it is possible to have ratings of about
200 MW
300 MW
400 MW
600 MW