1) A self excited d.c shunt generator, driven by its prime mover at the rated speed fails to build up the voltage across its terminals at no load. What reason can be assigned for this? (IES 2006)
a) The initial shunt field mmf does not assist the residual magnetism
b) The field circuit resistance is higher than the critical resistance
c) One of the inter-pole connection is removed
d) Brush axis slightly shift from the geometrical neutral axis of the machine
2) Wave winding is employed in a dc machine of: (IES 2006)
a) High current and low voltage rating
b) Low current and high voltage rating
c) High current and high voltage rating
d) Low current and low voltage rating
3) The resultant flux density in the air gap of a synchronous generator is the lowest during: (IES 2006)
a) Open circuit b) Solid short circuit c) Full load d) Half load
4) If the load of an Induction motor is increased from no load to full load, its slip and the power factor will respectively (IES 2006)
a) decrease, decrease
b) decrease, increase
c) increase, decrease
d) increase, increase
5) A single phase Induction motor is running at N rpm. Its synchronous speed is Ns. If its slip with respect to forward field is 's', what is the slip with respect to the backward field is: (IES 2006)
a) s b) –s c) (1-s) d) (2-s)
6) Match the following: (IES 2003)
List I List II
A. DC Motor 1. Circle Diagram
B. DC Generator 2. V-Curves
C. Alternator 3. Open circuit characteristics
D. Induction Motor 4.Speed-Torque characteristics
Codes:
A B C D
a) 4 3 1 2
b) 3 4 2 1
c) 4 3 2 1
d) 3 4 1 2
7) A smaller air gap in a polyphase induction motor helps to: (IES 2004)
a) reduces the chances of crawling
b) Increases the starting torque
c) reduces the chances of cogging
d) reduce the magnetising current
8) If the supply voltage of the induction motor is reduced by 10%. By what percentage approximately will the maximum torque decreases? (IES 2004)
a) 5% b) 10% c) 20% d) 40%
Answers:
(1) b (2) b (3) b (4) d(5) d (6) c (7) d (8) c
a) The initial shunt field mmf does not assist the residual magnetism
b) The field circuit resistance is higher than the critical resistance
c) One of the inter-pole connection is removed
d) Brush axis slightly shift from the geometrical neutral axis of the machine
2) Wave winding is employed in a dc machine of: (IES 2006)
a) High current and low voltage rating
b) Low current and high voltage rating
c) High current and high voltage rating
d) Low current and low voltage rating
3) The resultant flux density in the air gap of a synchronous generator is the lowest during: (IES 2006)
a) Open circuit b) Solid short circuit c) Full load d) Half load
4) If the load of an Induction motor is increased from no load to full load, its slip and the power factor will respectively (IES 2006)
a) decrease, decrease
b) decrease, increase
c) increase, decrease
d) increase, increase
5) A single phase Induction motor is running at N rpm. Its synchronous speed is Ns. If its slip with respect to forward field is 's', what is the slip with respect to the backward field is: (IES 2006)
a) s b) –s c) (1-s) d) (2-s)
6) Match the following: (IES 2003)
List I List II
A. DC Motor 1. Circle Diagram
B. DC Generator 2. V-Curves
C. Alternator 3. Open circuit characteristics
D. Induction Motor 4.Speed-Torque characteristics
Codes:
A B C D
a) 4 3 1 2
b) 3 4 2 1
c) 4 3 2 1
d) 3 4 1 2
7) A smaller air gap in a polyphase induction motor helps to: (IES 2004)
a) reduces the chances of crawling
b) Increases the starting torque
c) reduces the chances of cogging
d) reduce the magnetising current
8) If the supply voltage of the induction motor is reduced by 10%. By what percentage approximately will the maximum torque decreases? (IES 2004)
a) 5% b) 10% c) 20% d) 40%
Answers:
(1) b (2) b (3) b (4) d(5) d (6) c (7) d (8) c
2 comments:
regarding qeuestion2 the answer should bt a) because if it is unable to support the residual magnetism it will show 0 volts in "open circuit" also, otherwise the answer could have been field resistance..
will u please explain?
Union Public Services Commission (UPSC) will be conducting the examination for Indian Engineering Services (IES) in the January 2019. The candidates who successfully clear the examination will be selected for the posts in Civil, Electrical, Communication, Mechanical Engineering and etc. The notification was released earlier and the Application procedure is starting from 26th September 2018. Go through the article to know detailed information about the process of filling the IES Application Form2018.
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