871228
Descripción
Test por Vito Martino, actualizado hace más de 1 año
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Creado por Vito Martino
hace casi 10 años
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Pregunta 1
Pregunta
Which of the following formulas can calculate power in an ac circuit?
Respuesta
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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
Pregunta 2
Pregunta
What is the power produced by a 400v three phase system which delivers 25A at a power factor of 0.85
Respuesta
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14.72kW
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6.23kW
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10kW
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14kW
Pregunta 3
Pregunta
What is the power produced by a 400v three phase system which delivers 10A at a power factor of 0.7
Respuesta
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4849.6W
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4.7kW
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5000W
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4700W
Pregunta 4
Pregunta
The power factor of an installation can be calculated from
Respuesta
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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
Pregunta 5
Pregunta
The power factor of an inductive load can be improved by?
Respuesta
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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)
Pregunta 6
Pregunta
The power factor of a load consisting of inductance and resistance can be calculated from
Respuesta
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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
Pregunta 7
Pregunta
The formula required to calculate the total power of a single phase inductive load supplied by an a.c. supply is
Respuesta
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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
Pregunta 8
Pregunta
If the W is 100 and the VA is 120 what would the power factor be
Respuesta
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0.75
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0.2
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0.85
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0.83
Pregunta 9
Pregunta
If the kW is 200 and the KVA is 400 what would the power factor be?
Respuesta
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0.6
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0.7
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0.8
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0.5
Pregunta 10
Pregunta
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
Respuesta
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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
Pregunta 11
Pregunta
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
Respuesta
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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
Pregunta 12
Pregunta
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
Respuesta
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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
Pregunta 13
Pregunta
A three phase system gives the following readings
kVA =30 kW= 45
What is the power factor for the system
Respuesta
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0.67
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unity
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1.5
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0.8
Pregunta 14
Pregunta
A three phase system gives the following readings
kW= 400 kVA = 500
What is the power factor for the system
Respuesta
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1.25
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unity
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0.8
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0.6
Pregunta 15
Pregunta
What unit is reactive power measured in
Respuesta
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kA
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KVAr
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kW
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KVA
Pregunta 16
Pregunta
What unit is apparent power measured in
Respuesta
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kA
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KVAr
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kW
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KVA
Pregunta 17
Pregunta
What unit is true power measured in
Respuesta
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KVAr
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kA
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kW
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KVA
Pregunta 18
Pregunta
Which component would cause the current and voltage to behave as above
Image:
Slide2.JPG (image/JPG)
Respuesta
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resistor
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rectifier
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capacitor
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Inductor
Pregunta 19
Pregunta
Which component would cause the current and voltage to behave as above
Image:
Slide1.JPG (image/JPG)
Respuesta
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Inductor
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capacitor
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resistor
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rectifier
Pregunta 20
Pregunta
Which component would cause the current and voltage to behave as above
Image:
Slide3.JPG (image/JPG)
Respuesta
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Inductor
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capacitor
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resistor
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rectifier
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