871228
Description
Quiz by Vito Martino, updated more than 1 year ago
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Created by Vito Martino
almost 10 years ago
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Question 1
Question
Which of the following formulas can calculate power in an ac circuit?
Answer
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P = V x I x pf
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P = V + I
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P = V x I
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P = V/R
Question 2
Question
What is the power produced by a 400v three phase system which delivers 25A at a power factor of 0.85
Answer
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14.72kW
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6.23kW
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10kW
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14kW
Question 3
Question
What is the power produced by a 400v three phase system which delivers 10A at a power factor of 0.7
Answer
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4849.6W
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4.7kW
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5000W
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4700W
Question 4
Question
The power factor of an installation can be calculated from
Answer
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Cosθ = Z/X
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Cosθ = X/Z
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Cosθ = KVA/KW
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Cosθ = KW/KVA
Question 5
Question
The power factor of an inductive load can be improved by?
Answer
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Connecting a inductor across the load
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Connecting a resistor in parallel with the load
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Connecting a capacitor in series with the load
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Connecting a capacitor across the load (parallel)
Question 6
Question
The power factor of a load consisting of inductance and resistance can be calculated from
Answer
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Cosθ = True Power/Apparent Power
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Cosθ = Apparent Power/ Reactive Power
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Cosθ = Reactive Power/True Power
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Cosθ = Apparent Power/True Power
Question 7
Question
The formula required to calculate the total power of a single phase inductive load supplied by an a.c. supply is
Answer
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P = IV sinθ
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P = IV
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P = IV tanθ
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P = IV cosθ
Question 8
Question
If the W is 100 and the VA is 120 what would the power factor be
Answer
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0.75
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0.2
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0.85
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0.83
Question 9
Question
If the kW is 200 and the KVA is 400 what would the power factor be?
Answer
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0.6
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0.7
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0.8
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0.5
Question 10
Question
A single phase circuit draws a current of 21.7A from a 230 V circuit at a power factor of 0.4
What is the current drawn if the power factor is corrected to 0.85
Answer
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18.4 A
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23.4 A
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10.21 A
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21.7 A
Question 11
Question
A circuit dissipates 2000 W at a power factor of 0.5 when connected to a 230 V ac supply. The current drawn from the supply is
Answer
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17.8 A
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17.39 A
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4.3 A
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8.7 A
Question 12
Question
A circuit dissipates 1.5 kW at a power factor of 0.75 when connected to a 230V ac supply. The current drawn from the supply is
Answer
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7.8 A
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9.2 A
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6.5 A
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8.7 A
Question 13
Question
A three phase system gives the following readings
kVA =30 kW= 45
What is the power factor for the system
Answer
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0.67
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unity
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1.5
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0.8
Question 14
Question
A three phase system gives the following readings
kW= 400 kVA = 500
What is the power factor for the system
Answer
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1.25
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unity
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0.8
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0.6
Question 15
Question
What unit is reactive power measured in
Answer
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kA
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KVAr
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kW
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KVA
Question 16
Question
What unit is apparent power measured in
Answer
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kA
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KVAr
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kW
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KVA
Question 17
Question
What unit is true power measured in
Answer
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KVAr
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kA
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kW
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KVA
Question 18
Question
Which component would cause the current and voltage to behave as above
Image:
Slide2.JPG (image/JPG)
Answer
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resistor
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rectifier
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capacitor
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Inductor
Question 19
Question
Which component would cause the current and voltage to behave as above
Image:
Slide1.JPG (image/JPG)
Answer
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Inductor
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capacitor
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resistor
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rectifier
Question 20
Question
Which component would cause the current and voltage to behave as above
Image:
Slide3.JPG (image/JPG)
Answer
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Inductor
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capacitor
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resistor
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rectifier
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