giannini.chambers
Quiz by , created more than 1 year ago

unknown JTL Unit 36 and 38 Revision Quiz on Unit 36 Mock Exam, created by giannini.chambers on 22/04/2015.

162
1
0
giannini.chambers
Created by giannini.chambers about 9 years ago
Close

Unit 36 Mock Exam

Question 1 of 19

1

An inductor of 300mH placed on a 60Hz network will have an inductive reactance of?

Select one of the following:

  • 113Ω

  • 100Ω

  • 113097Ω

  • 97Ω

Explanation

Question 2 of 19

1

A capacitor of 90µF is placed on an electrical network of frequency 65 Hz. What is the value of capacitive reactance?

Select one of the following:

  • 27Ω

  • 27000000Ω

  • 27000Ω

  • 0.0027Ω

Explanation

Question 3 of 19

1

What is the typical generation voltage at a power station?

Select one of the following:

  • 25kV

  • 125kV

  • 11kV

  • 33kV

Explanation

Question 4 of 19

1

Where is the neutral connected on the secondary of a delta to star transformer?

Select one of the following:

  • The end of every line

  • The star point of the transformer

  • To the middle of every winding

  • Left floating

Explanation

Question 5 of 19

1

What is the phase separation angle in a typical star system between phases?

Select one of the following:

  • 100°

  • 120°

  • 360°

  • 110°

Explanation

Question 6 of 19

1

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?

Select one of the following:

  • 100Ω

  • 50Ω

  • 75Ω

  • 124Ω

Explanation

Question 7 of 19

1

What is the series impedance of a circuit where the resistance is 30Ω the inductive reactance is 70Ω and the capacitive reactance is 30Ω?

Select one of the following:

  • 50Ω

  • 65Ω

  • 70Ω

  • 40Ω

Explanation

Question 8 of 19

1

If you have a star phase voltage of 135V what would the line voltage be?

Select one of the following:

  • 234V

  • 200V

  • 78V

  • 75V

Explanation

Question 9 of 19

1

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:

Select one of the following:

  • 47A

  • 40A

  • 37A

  • 50A

Explanation

Question 10 of 19

1

What type of light fitting requires no control gear?

Select one of the following:

  • Incandescent

  • Fluorescent

  • Sodium Discharge

  • High pressure mercury

Explanation

Question 11 of 19

1

Which type of protective device natively offers the functions of earth fault, residual current and short circuit protection?

Select one of the following:

  • RCBO

  • MCB

  • RCD

  • ACB

Explanation

Question 12 of 19

1

A light source of 300 Candela is placed 2.5m above a table. Calculate the illuminance at a point directly below the light fitting.

Select one of the following:

  • 48 Lux

  • 48 Lumens

  • 120 Lux

  • 120 Lumens

Explanation

Question 13 of 19

1

The full load current of a transformer is 650A and the voltage is 400V between phases. Calculate the apparent power rating of the transformer.

Select one of the following:

  • 450kVA

  • 400kVA

  • 180kVA

  • 400kW

Explanation

Question 14 of 19

1

In a TT system the means of earthing is provided by:

Select one of the following:

  • Distributor's earth supply

  • Installation earth electrode

  • Combined neutral and earth

  • None it is an earth free location

Explanation

Question 15 of 19

1

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?

Select one of the following:

  • 270V and 468V

  • 468V

  • 270V, 468V and 135V

  • 300V

  • 300V and 500V

Explanation

Question 16 of 19

1

Calculate the angle the current lags the voltage in a network where there is 30kW and 12kVAr on the network.

Select one of the following:

  • 21.8°

  • 18°

  • 25°

  • 26.7°

Explanation

Question 17 of 19

1

A centre tapped to earth transformer has a voltage of 75V phase to earth. What would the full voltage available be?

Select one of the following:

  • 150V

  • 100V

  • 37.5V

  • 130V

Explanation

Question 18 of 19

1

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.

Select one of the following:

  • 1000W

  • 1640W

  • 1530W

  • 2160W

Explanation

Question 19 of 19

1

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?

Select one of the following:

  • 10A

  • 250000A

  • 4V

  • 4A

Explanation

Previous
Next