This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Applications of
Power Electronics-1”.
1. SMPS is used for
a) obtaining controlled ac power supply
b) obtaining controlled dc power supply
c) storage of dc power
d) switch from one source to another
View Answer
Answer: b
Explanation: SMPS (Switching mode power supply) is used for obtaining controlled dc power supply.
2. SPMS are based on the ________ principle.
a) Phase control
b) Integral control
c) Chopper
d) MOSFET
View Answer
Answer: c
Explanation: SMPS (Switching mode power supply) are based on the chopper principle. The output dc
voltage is controlled by varying the duty cycle of the chopper circuit.
3. Choose the incorrect statement.
a) SMPS is less sensitive to input voltage variations
b) SMPS is smaller as compared to rectifiers
c) SMPS has low input ripple
d) SMPS is a source of radio interference
View Answer
Answer: c
Explanation: SMPS has higher output ripple and its regulation is worse.
4. _________ is used for critical loads where temporary power failure can cause a great deal of
inconvenience.
a) SMPS
b) UPS
c) MPS
d) RCCB
View Answer
Answer: b
Explanation: Uninterruptible Power Supply is used where loads where temporary power failure can
cause a great deal of inconvenience.
5. __________ is used in the rotating type UPS system to supply the mains.
a) DC motor
b) Self excited DC generator
c) Alternator
d) Battery bank
View Answer
Answer: c
Explanation: When the supply is gone, the diesel engine is started, which runs the alternator and the
alternator supplies power to the mains. Non-rotating type UPS are not used anymore.
6. Static UPS requires __________
a) only rectifier
b) only inverter
c) both inverter and rectifier
d) none of the mentioned
View Answer
Answer: c
Explanation: Rectifier to converter the dc from the battery to ac. Inverter to charge the battery from
mains.
7. No discontinuity is observed in case of
a) short break static UPS configuration
b) long break static UPS configuration
c) no break static UPS configuration
d) rotating type UPS configuration
View Answer
Answer: c
Explanation: No dip or discontinuity is observed in case of no break static UPS configuration, as the
battery inverter set immediately takes over the mains.
8. Usually __________ batteries are used in the UPS systems.
a) NC
b) Li-On
c) Lead acid
d) All of the mentioned
View Answer
Answer: c
Explanation: Lead acid batteries are cheaper and have certain advantages over the other types. NC
batteries would however be the best, but are three to four times more expensive than Lead Acid.
9. HVDC transmission has ___________ as compared to HVAC transmission.
a) smaller transformer size
b) smaller conductor size
c) higher corona loss
d) smaller power transfer capabilities
View Answer
Answer: b
Explanation: The conductor size is smaller as there is no sink effect, and the whole conductor is utilized
for transmitting power.
10. The negative polarity is used in the monopolar link because it
a) uses less conductor size
b) is safer
c) produces less radio interference
d) has less resistance
View Answer
Answer: c
Explanation: The monopolar link uses just a single conductor, which is usually negative as it produces
less radio interference and corona.
11.
Which is the advantage of AC
drive?
A.
Power and control circuit are
simple
B.
Speed and design ratios have upper
limits
C.
Produce a simulated wave form
D.
Heavy windings required
✓ (B). Speed and design ratios have upper
limits is Right Answer
12.
Which colour LED indicates the fault
occurred in drives?
A.
Green
B.
Yellow
C.
Red
D.
Blue
✓ (C). Red is Right Answer
13.
What is the expansion of
UPS?
A.
Uninterrupted Power System
B.
Uninterrupted Power Supply
C.
Uninterrupted Power Solution
D.
Uninterrupted Power Section
✓ (B). Uninterrupted Power Supply is Right Answer
14.
Which circuit diagram is
illustrated?
A.
ON line UPS
B.
OFF line UPS
C.
Bridge rectifier
D.
Metal rectifier
✓ (A). ON line UPS is Right Answer
15.
Which part is marked as in the block
diagram of OFF line UPS?
A.
Reset switch
B.
Change over switch
C.
Control panel
D.
Battery charger
✓ (D). Battery charger is Right Answer
16.
What is the relation between back up
time and capacity of the battery of an UPS?
A.
Capacity of battery increases back up time
increases
B.
Capacity of battery increases back up time
decreases
C.
Capacity of battery decreases back up time
increases
D.
Capacity of battery has no relations with
back up time
✓ (A). Capacity of battery increases back up time
increases is Right Answer
17.
Which component is connected
across the transformer winding of an UPS for protection from lightning?
A.
Diode
B.
Transistor
C.
Triode
D.
Polyster capacitor
✓ (D). Polyster capacitor is Right Answer
18.
Which electrical / electronic device
requires ups?
A.
Air conditioner
B.
Micro wave oven
C.
Computer
D.
Television
✓ (C). Computer is Right Answer
19.
Why the battery is to be placed
nearer to ups in ups wiring?
A.
To minimise the length of cable
B.
For safety reasons
C.
To increase the life of battery
D.
To reduce voltage drop
✓ (D). To reduce voltage drop is Right Answer
20.
What adjustment is to be done in
commercial installation for interconnection of two or more UPS?
A.
By connecting manually
B.
By using a change over relay
C.
By using rotary switch
D.
By using ICDP switch
✓ (B). By using a change over relay is Right Answer