Unit 36 Mock Exam

Descrição

unknown JTL Unit 36 and 38 Revision Quiz sobre Unit 36 Mock Exam, criado por giannini.chambers em 22-04-2015.
giannini.chambers
Quiz por giannini.chambers, atualizado more than 1 year ago
giannini.chambers
Criado por giannini.chambers mais de 9 anos atrás
162
1

Resumo de Recurso

Questão 1

Questão
An inductor of 300mH placed on a 60Hz network will have an inductive reactance of?
Responda
  • 113Ω
  • 100Ω
  • 113097Ω
  • 97Ω

Questão 2

Questão
A capacitor of 90µF is placed on an electrical network of frequency 65 Hz. What is the value of capacitive reactance?
Responda
  • 27Ω
  • 27000000Ω
  • 27000Ω
  • 0.0027Ω

Questão 3

Questão
What is the typical generation voltage at a power station?
Responda
  • 25kV
  • 125kV
  • 11kV
  • 33kV

Questão 4

Questão
Where is the neutral connected on the secondary of a delta to star transformer?
Responda
  • The end of every line
  • The star point of the transformer
  • To the middle of every winding
  • Left floating

Questão 5

Questão
What is the phase separation angle in a typical star system between phases?
Responda
  • 100°
  • 120°
  • 360°
  • 110°

Questão 6

Questão
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?
Responda
  • 100Ω
  • 50Ω
  • 75Ω
  • 124Ω

Questão 7

Questão
What is the series impedance of a circuit where the resistance is 30Ω the inductive reactance is 70Ω and the capacitive reactance is 30Ω?
Responda
  • 50Ω
  • 65Ω
  • 70Ω
  • 40Ω

Questão 8

Questão
If you have a star phase voltage of 135V what would the line voltage be?
Responda
  • 234V
  • 200V
  • 78V
  • 75V

Questão 9

Questão
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:
Responda
  • 47A
  • 40A
  • 37A
  • 50A

Questão 10

Questão
What type of light fitting requires no control gear?
Responda
  • Incandescent
  • Fluorescent
  • Sodium Discharge
  • High pressure mercury

Questão 11

Questão
Which type of protective device natively offers the functions of earth fault, residual current and short circuit protection?
Responda
  • RCBO
  • MCB
  • RCD
  • ACB

Questão 12

Questão
A light source of 300 Candela is placed 2.5m above a table. Calculate the illuminance at a point directly below the light fitting.
Responda
  • 48 Lux
  • 48 Lumens
  • 120 Lux
  • 120 Lumens

Questão 13

Questão
The full load current of a transformer is 650A and the voltage is 400V between phases. Calculate the apparent power rating of the transformer.
Responda
  • 450kVA
  • 400kVA
  • 180kVA
  • 400kW

Questão 14

Questão
In a TT system the means of earthing is provided by:
Responda
  • Distributor's earth supply
  • Installation earth electrode
  • Combined neutral and earth
  • None it is an earth free location

Questão 15

Questão
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?
Responda
  • 270V and 468V
  • 468V
  • 270V, 468V and 135V
  • 300V
  • 300V and 500V

Questão 16

Questão
Calculate the angle the current lags the voltage in a network where there is 30kW and 12kVAr on the network.
Responda
  • 21.8°
  • 18°
  • 25°
  • 26.7°

Questão 17

Questão
A centre tapped to earth transformer has a voltage of 75V phase to earth. What would the full voltage available be?
Responda
  • 150V
  • 100V
  • 37.5V
  • 130V

Questão 18

Questão
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.
Responda
  • 1000W
  • 1640W
  • 1530W
  • 2160W

Questão 19

Questão
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?
Responda
  • 10A
  • 250000A
  • 4V
  • 4A

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