Тест по High Voltage, Fundamentals (CES v5.0)

Результати проходження тесту

Ваш результат: 88%
Зберегти у моєму резюме
Повернутись до тесту
Правильні відповіді:
1

A 440 Volt AC source supplies 2 loads in parallel. The left load has an impedance of 44 Ohms and the right of 11 Ohms. Which of the following is the current taken from the AC supply?

Ваша відповідь правильна:

50 Amps.
2

A man accidently receives an electric shock resulting in a current of 2 mA flowing through his hands and chest. Which of the following best describes the likely effect on him?

Ваша відповідь правильна:

He will feel tingling or mild pain.
3

An AC circuit delivers an active power of 30 kW when supplied at 400 Volts and 125 Amps. Which of the following is the reactive power?

Ваша відповідь правильна:

40 kVAr.
4

An AC electrical circuit operates at 110 Volts. Which one of the following is the circuit’s voltage rating according to this module?

Ваша відповідь правильна:

Low Voltage.
5

An overcurrent relay is usually used to open a circuit breaker. Which one of the following is another function it may be used for?

Ваша відповідь правильна:

To sound an alarm.
6

How do electrical engineers refer to a flow of electricity around a circuit?

Ваша відповідь правильна:

It is referred to as a current, represented by I.
7

In analyzing AC electrical circuits, it is common practice to use impedances. Which one of the following best describes what an “impedance” is?

Ваша відповідь правильна:

It expresses the practical effect of resistance, capacitance and inductance for a single or group of components.
8

PVC insulated cable is very popular ashore. Which one of the following best describes the reason why it is less frequently used on ships?

Ваша відповідь правильна:

It gives off poisonous halogen gas if on fire.
9

Sometimes conductors are separated to prevent short circuits, using the insulating effect of the air to contain the electricity. Which 2 of the following are reasons why the gap between conductors may be larger than the minimum necessary for the rated voltage?

Ваша відповідь правильна:

To allow space for tools to be used.; Where there is a higher than usual risk of short circuit.
10

Sometimes it is possible to see electrical conductors, such as busbars, which have no insulation covering parts of them. Which one of the following best describes why these uninsulated live parts do not normally cause a short circuit?

Ваша відповідь правильна:

The surrounding air has been used as the insulation.
11

The basic strategy to stay alive while working with high voltage systems may be summarized as DIE. What does DIE stand for?

Ваша відповідь правильна:

Disconnect, Isolate, Earth.
12

The battery in the circuit shown has an output of 1,5 Volts. The resistors are 32,75 Ohms each. What voltage is dropped across the right hand resistor?

Ваша відповідь правильна:

1,5 Volts.
13

The battery in the circuit shown has an output of 12 Volts. If the resistance of the resistor is 3 Ohms what current should be flowing in the circuit?

Ваша відповідь правильна:

4 Amps.
14

The battery in the circuit shown has an output of 12 Volts. If the resistance of the upper resistor is 3 Ohms what current should be flowing in the circuit?

Ваша відповідь правильна:

It cannot be calculated from the information given.
15

The battery in the circuit shown has an output of 12 Volts. The resistors are 3 Ohms each. What current should be flowing through the battery connections?

Ваша відповідь правильна:

12 Amps.
16

The battery in the circuit shown has an output of 24 Volts. If the resistance of the upper resistor is 3 Ohms and the lower resistor is 5 Ohms what current should be flowing in the circuit?

Ваша відповідь правильна:

3 Amps.
17

The battery in the circuit shown has an output of 6 Volts. If the resistance of the resistor is 0,5 Ohms what current should be flowing?

Правильну відповідь:

12 Amps.

Ваша відповідь:

3 Amperes.
18

The battery in the circuit shown has an output of 6 Volts. If the resistance of the upper resistor is 3 Ohms and the current flowing in the circuit is 1 Amp, then what voltage is dropped across the upper resistor according to Kirchhoff’s Law?

Ваша відповідь правильна:

3 Volts.
19

The battery in the circuit shown has an output of 6 Volts. The resistance of the upper resistor is 3 Ohms and the lower resistor is 9 Ohms. What voltage is dropped across the upper resistor according to Kirchhoff’s Voltage Law?

Ваша відповідь правильна:

1,5 Volts.
20

The battery in the circuit shown has an output of 6 Volts. The voltage dropped across the upper resistor is 2 Volts. What voltage is dropped across the lower resistor according to Kirchhoff’s Law?

Ваша відповідь правильна:

4 Volts.
21

Thermosetting insulation has been used on the cases of 2 circuit breakers, one rated for low voltage and the other for high voltage. Which of the following options best describes the difference that can be seen in the insulation?

Ваша відповідь правильна:

The insulation will be thicker on the high voltage breaker.
22

Two electrical conductors are circular in cross section and are otherwise the same except that conductor 1 has twice the diameter of conductor 2. If the resistance of conductor 1 is 2 Ohms what is the resistance of conductor 2?

Ваша відповідь правильна:

8 Ohms.
23

Two electrical conductors are the same except that conductor 1 is four times as long as conductor 2. If the resistance of conductor 1 is 2 Ohms what is the resistance of conductor 2?

Ваша відповідь правильна:

0,5 Ohms.
24

Two identical coils are connected in separate electrical circuits. One coil is supplied by a 12 Volt DC source and the other by a 12 Volt AC source. Which one of the following describes which circuit will have the higher current flowing and why?

Ваша відповідь правильна:

The DC circuit – because the inductance does not restrict current flow.
25

When calculating the resistance of an electrical conductor which one of the following is the symbol used to denote the resistivity of the conductor material?

Ваша відповідь правильна:

The symbol ρ.
26

Which of the following allows the heat being produced in a conductor carrying a current to be calculated?

Ваша відповідь правильна:

I2×R.
27

Which of the following best describes how a capacitor works?

Ваша відповідь правильна:

It stores energy like a fast charging battery.
28

Which of the following best describes how the apparent power of an AC electrical circuit with a single coil as a load can be calculated?

Ваша відповідь правильна:

P = V×I.
29

Which of the following best describes one of the ways that might cause an electrical conductor to suffer voltage overload?

Правильну відповідь:

Accidental connection to the wrong supply.

Ваша відповідь:

Insulation too thin.
30

Which of the following best describes one reason why people receiving electric shocks from high voltage (HV) systems are more likely to die than those receiving shocks from low voltage (LV) systems?

Ваша відповідь правильна:

The safe exposure time to current falls rapidly as the voltage increases.
31

Which of the following best describes the effect of over voltage when applied to an electrical conductor?

Ваша відповідь правильна:

It will cause insulation breakdown.
32

Which of the following best describes the meaning of the symbol Ω when found in an electrical calculation?

Ваша відповідь правильна:

The quantity is expressed in Ohms.
33

Which of the following best describes the reason why designers of electrical systems sometimes specify cables with a greater current carrying capacity than the current predicted to flow in service?

Ваша відповідь правильна:

The cables are to be installed in a large bundle on the boiler.
34

Which of the following best describes what we mean by “power factor” in an AC electrical system?

Ваша відповідь правильна:

It is the proportion of apparent power which is delivered as active power.
35

Which of the following best describes why traditionally ships’ electrical systems have operated with an insulated neutral?

Ваша відповідь правильна:

So as to minimise the risk of essential equipment tripping.
36

Which of the following is the level at which electricity becomes high voltage, according to the International Electro-Technical Commission standard for ships?

Ваша відповідь правильна:

AC electricity above 1 000 Volts.
37

Which of the following options best explains how we ensure that electricity flows from the power supply to the load without it “leaking” away?

Правильну відповідь:

The conductor is surrounded by insulation to prevent leakage.

Ваша відповідь:

The conductor is surrounded by wire mesh to prevent leakage.
38

Which one of the following best describes reactive power in an AC electrical circuit?

Ваша відповідь правильна:

Reactive power is easily converted back to electricity.
39

Which one of the following best describes the meaning of “voltage stress” when applied to ship’s electrical cables?

Ваша відповідь правильна:

It is the voltage per millimetre of insulation.
40

Which one of the following best describes the primary method of protecting against overloading of an electrical conductor?

Ваша відповідь правильна:

The conductors must be adequately rated for maximum load current under the worst environmental conditions expected.
41

Which one of the following best describes what the difference is between the thermosetting and the thermoplastic insulations used on ship’s electrical equipment?

Ваша відповідь правильна:

Thermoplastic insulations soften as they get warmer and thermosetting insulations do not.
42

Which one of the following best describes why a length of 10 Amp cable bought from a shop ashore may not be suitable for a circuit carrying 10 Amps on a ship?

Ваша відповідь правильна:

Temperatures on ships are often higher than ashore so that the conductor may not be cooled as effectively as assumed by the seller.
43

Which one of the following best describes why arc and blast are more of a problem with high voltage (HV) electrical systems?

Ваша відповідь правильна:

The amount of energy available in a HV circuit tends to be much higher.
44

Which one of the following best describes why most circuits on ships are supplied by AC electricity rather than DC?

Ваша відповідь правильна:

The voltage level of AC is easily changed.
45

Which one of the following describes the best way of protecting the conductors deep inside electrical machines from the effects of excessive temperature?

Ваша відповідь правильна:

Thermistors can be built into them to sense the temperature.
46

Which one of the following describes the best way to protect an electrical cable from mechanical damage where it passes through an area on deck where cargo is loaded and unloaded?

Ваша відповідь правильна:

Run the cable through steel conduit.
47

Which one of the following formulas agrees with Ohms Law?

Правильну відповідь:

R = V/I.

Ваша відповідь:

R = V×I.
48

Which one of the following is the most common reason for a rapid rise in the current flowing through an electrical circuit, to a level many times its rated value?

Ваша відповідь правильна:

A short circuit.
49

Which one of the following options best describes a possible cause for the softening and weakening of the insulation around an electrical cable?

Ваша відповідь правильна:

Unexpectedly high ambient temperature.
50

Which one of the following options best describes a possible reason for someone being seriously hurt following an electric shock of 10 mA, even though the current passed through the body for only a fraction of a second?

Ваша відповідь правильна:

They were thrown backwards and fractured their head.
51

Which one of the following options best describes a significant problem with thermosetting types of insulation on ships?

Правильну відповідь:

Thermosetting insulation is not flexible and can become damaged by impacts.

Ваша відповідь:

Thermosetting insulation is too expensive.
52

Which one of the following options best describes the effect on an electrical cable on a ship if the cable is hit by a lightning strike?

Правильну відповідь:

A voltage overload and damage to cable insulation.

Ваша відповідь:

No effect to a cable rated at over 6 kiloVolts.
53

Which one of the following options best describes what happens when a charged capacitor is connected to a load in an electrical circuit?

Ваша відповідь правильна:

A DC current will flow in the opposite direction to the one that charged it.
54

Which one of the following options best describes why connecting cables are usually fitted with flexible insulation?

Ваша відповідь правильна:

Flexible insulation is necessary so connections can be made.
55

Which one of the following options is the way we refer to the restriction to current flow through an inductor in an AC electrical circuit? Refer to the blackboard on the right side of the screen:

Правильну відповідь:

4.

Ваша відповідь:

2.
56

Which one of the following would be a typical power factor for a 440 Volt galley stove?

Ваша відповідь правильна:

1.
Пройти тест ще разПосилання на результати