2562068
Descripción
Test por giannini.chambers, actualizado hace más de 1 año
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Creado por giannini.chambers
hace más de 9 años
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Pregunta 1
Pregunta
An inductor of 300mH placed on a 60Hz network will have an inductive reactance of?
Respuesta
-
113Ω
-
100Ω
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113097Ω
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97Ω
Pregunta 2
Pregunta
A capacitor of 90µF is placed on an electrical network of frequency 65 Hz. What is the value of capacitive reactance?
Respuesta
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27Ω
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27000000Ω
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27000Ω
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0.0027Ω
Pregunta 3
Pregunta
What is the typical generation voltage at a power station?
Respuesta
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25kV
-
125kV
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11kV
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33kV
Pregunta 4
Pregunta
Where is the neutral connected on the secondary of a delta to star transformer?
Respuesta
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The end of every line
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The star point of the transformer
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To the middle of every winding
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Left floating
Pregunta 5
Pregunta
What is the phase separation angle in a typical star system between phases?
Respuesta
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100°
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120°
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360°
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110°
Pregunta 6
Pregunta
A voltage of 700V is applied to two resistors in series. A current of 2.8A flows. If one of the resistors is 150Ω what is the value of the other?
Respuesta
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100Ω
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50Ω
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75Ω
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124Ω
Pregunta 7
Pregunta
What is the series impedance of a circuit where the resistance is 30Ω the inductive reactance is 70Ω and the capacitive reactance is 30Ω?
Respuesta
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50Ω
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65Ω
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70Ω
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40Ω
Pregunta 8
Pregunta
If you have a star phase voltage of 135V what would the line voltage be?
Respuesta
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234V
-
200V
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78V
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75V
Pregunta 9
Pregunta
A 30kW lift motor is running at 0.95 power factor. Calculate the line current that is drawn from the supply when the voltage is 390V:
Respuesta
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47A
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40A
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37A
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50A
Pregunta 10
Pregunta
What type of light fitting requires no control gear?
Respuesta
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Incandescent
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Fluorescent
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Sodium Discharge
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High pressure mercury
Pregunta 11
Pregunta
Which type of protective device natively offers the functions of earth fault, residual current and short circuit protection?
Respuesta
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RCBO
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MCB
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RCD
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ACB
Pregunta 12
Pregunta
A light source of 300 Candela is placed 2.5m above a table. Calculate the illuminance at a point directly below the light fitting.
Respuesta
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48 Lux
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48 Lumens
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120 Lux
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120 Lumens
Pregunta 13
Pregunta
The full load current of a transformer is 650A and the voltage is 400V between phases. Calculate the apparent power rating of the transformer.
Respuesta
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450kVA
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400kVA
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180kVA
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400kW
Pregunta 14
Pregunta
In a TT system the means of earthing is provided by:
Respuesta
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Distributor's earth supply
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Installation earth electrode
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Combined neutral and earth
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None it is an earth free location
Pregunta 15
Pregunta
The phase voltage supplied to a building is 270V. The building is given a 3 phase 3 wire supply. What voltage are available to work with?
Respuesta
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270V and 468V
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468V
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270V, 468V and 135V
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300V
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300V and 500V
Pregunta 16
Pregunta
Calculate the angle the current lags the voltage in a network where there is 30kW and 12kVAr on the network.
Respuesta
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21.8°
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18°
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25°
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26.7°
Pregunta 17
Pregunta
A centre tapped to earth transformer has a voltage of 75V phase to earth. What would the full voltage available be?
Respuesta
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150V
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100V
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37.5V
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130V
Pregunta 18
Pregunta
A 25kW load is being drawn from a supply at 350V. Calculate the power loss through the conductor if the resistance is measured at 0.3Ω.
Respuesta
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1000W
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1640W
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1530W
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2160W
Pregunta 19
Pregunta
The potential difference between a cat and the earth is 1000V. If the resistance of the cat is measured at 250Ω what would the current flow to earth be?
Respuesta
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10A
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250000A
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4V
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4A
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