家在线测试 Ch-Eng / 2nd-Eng Test for seamans about Electrical Safety

在线测试： Test for seamans about Electrical Safety

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问题 1 从 38

At voltages of less than 1 000 V, what is the generally accepted minimum value of insulation resistance for electrical equipment on board ships?

One thousand ohms (1 kΩ).

One megohm (1 MΩ).

One hundred megohms (100 MΩ).

One hundred kilohms (100 kΩ).

For a ship’s electrical system, which one of the following statements best describes the meaning of the term “earth”?

The steelwork of the hull, whose electrical potential can be regarded as zero.

Any electrical conductor not on the live side of the supply.

An electrical connection only used in dry-dock.

Any part of the electrical system insulated from live conductors.

If a fluorescent tube or energy saving light bulb breaks, in addition to ensuring good ventilation, which one of the following statements best describes how the pieces should be cleaned up?

Use rubber gloves, sticky tape or wet towels to clean the area, place all materials in a marked sealed container for disposal ashore.

Sweep the pieces up with a brush and place all materials in a marked sealed container for disposal ashore.

Collect the pieces using rubber gloves, wet towels or sticky tape, grind all materials to less than 25 mm and then they can be thrown overboard once more than 25 miles from land.

Call in a specialist firm to clean up and dispose of the waste.

If any part of a live electrical circuit is brought into accidental contact with earth, then which one of the following statements should we assume to be correct?

All circuit are protected against any damage occurring.

Nothing will ever happen if the ship has an insulated neutral.

It is an unsafe situation.

Nothing will ever happen if the ship has an earthed neutral.

If unsure whether electrical equipment is live or not, the best course of action to take is to:

Treat it as though it were live until a competent person has proved it dead.

Wear gloves and apply a short across the terminals to see if there is any sparking.

Connect an ammeter between any two terminals.

Assume it must be dead if it looks as though it has been disconnected.

If work is to be carried out only on one part of a lighting circuit controlled by fuses or a miniature circuit breaker (MCB), which one of the following options is the best way to proceed?

With the system still alive, carefully disconnect the part of the circuit to be worked on.

Leave the fuses or MCB in, but switch off the circuit to be worked on.

Use a rubber mat and insulated tools and work carefully, knowing the system is alive.

Switch off all the other lights first and then withdraw the fuses or MCB for the whole circuit.

Once you are sure the power has been turned off, what is the next step in helping someone who has received an electric shock?

Check airway, breathing and circulation.

Start looking for burn injuries.

Get them out into fresh air.

Raise the alarm and do nothing until someone with first aid training arrives.

Outside of a hazardous area, which one of the following statements best describes the choice of portable electrical equipment when working in wet areas or galleys?

Portable electrical equipment supplied from a 110 Volt centre-tapped transformer should be used rather than mains voltage equipment.

Any portable equipment will be suitable, as this is a safe area.

Portable electrical equipment should never be used in such an area.

Only portable electrical equipment supplied at less than 12 Volts should be used.

The flow of unwanted leakage current through surface deposits on electrical cables is known as which one of the following?

Creeping.

Tracking.

The corona effect.

St. Elmo’s fire.

The relationship between voltage, current and resistance in an electrical circuit can be described by which one of the following statements?

The higher the voltage, or the lower the resistance, the higher the current.

The lower the voltage, or the lower the resistance, the lower the current.

The higher the voltage, or the higher the resistance, the lower the current.

The higher the voltage, or the lower the resistance, the lower the current.

What should be your first action if you see someone receiving an electric shock?

Turn off the electrical supply or get the victim clear of any live electrical conductors.

Check the victim’s pulse.

Check the victim’s breathing.

Grab hold of the victim to prevent them falling.

Which THREE of the following are true reasons why electrical equipment needs to be designed and approved for use in a hazardous area?

Explosive gas can enter equipment.

High energy sparks can ignite flammable gasses.

Working temperatures can reach the ignition temperature of the gas.

Even very low voltage or current is dangerous in hazardous area.

回答

Which TWO of the following conditions should be met before working on or testing any electrical equipment in a hazardous area?

A permit to work system should be used.

Only component, suitably trained and experienced persons should carry out the work.

A gas free certificate must always be obtained.

A zero flammable gas reading must be obtained.

回答

Which one of the following current paths for an electric shock is considered the most dangerous to the human body?

From hand to hand, across the chest.

From one hand to the ground.

From both hands to the ground.

From one foot across to the other foot.

Which one of the following gasses is given off during the normal charging of vented lead-acid batteries?

Hydrogen.

Hydrogen Sulphide.

Carbon Dioxide.

Hydrogen Peroxide.

Which one of the following is the main purpose of a rubber mat placed on the floor next to electrical equipment?

To provide a heat resistant surface.

To be a conductive surface and reduce the risk of sparks from static electricity.

To provide an insulating surface to reduce the risks from an electrical shock.

To prevent damage to equipment during maintenance.

Which one of the following options correctly completes the following statement? Electrical equipment is said to be “live”…

Only when it is connected to an electrical supply.

When it is supplied with or contains an electrical voltage or current.

When it is in operation or still moving.

Only when it is taking current from the supply.

Which one of the following options correctly completes the following statement? Electrical equipment is said to be “dead” when…

It is not connected to an electrical supply and any stored electrical energy has been discharged.

It has been switched off by means of a double pole switch.

It has been switched off and disconnected from an electrical supply.

It is no longer in operation.

Which one of the following statements best describes a safer alternative to checking voltages on live electrical equipment during fault finding?

Operate contractors by hand using an insulated screwdriver.

Isolate the equipment, then dismantle it and find the fault.

Keep the equipment live and check for loose connections using an insulated screwdriver.

Make the circuit dead and carry out low resistance (continuity) tests.

Which one of the following statements best describes how much electrical resistance the human body has?

The resistance of the human body decreases with higher voltages, sweat or damp conditions.

The resistance of the human body is fairly constant at around 5 000 Ohms for the average person.

The resistance of the human body increases with temperature and humidity.

The resistance of the human body is fairly constant at around 2 000 Ohms for the average person.

Which one of the following statements best describes the testing of live electrical equipment?

Live testing should only be carried out by competent persons using approved equipment and PPE, and only when essential.

Live testing should never be carried out under any circumstances.

Provided approved instruments are used, there is no problem with live testing.

Provided insulated leads with finger guards are used, there is no problem with live testing.

Which one of the following statements best describes which voltage level can be considered as “safe”?

Below 50 Volts is generally considered safe as regards electric shock, but lower voltages still present some risks.

Below 12 Volts is considered completely safe.

Below 110 Volts is considered completely safe, apart from in hazardous areas.

Below 24 Volts is considered completely safe, apart from in hazardous areas.

Which one of the following statements best describes why meter test leads should have finger guards fitted?

To provide a better grip for holding the test leads.

To prevent accidental contact between the hands and conductors which might be live.

To prevent damage to insulated gloves from the sharp edges of test probes.

To prevent injury to the hands from the sharp edges of test probes.

Which one of the following statements correctly describes how batteries or their contents should be disposed of?

Batteries and their contents should always be treated as controlled, special waste.

Apart from Cadmium batteries, most other batteries do not present any special risk and can be treated as other, non-food, waste.

Once drained of any liquids, batteries can be treated as other, non-food, waste.

Once drained of any liquids, batteries can be treated in the same way as plastics.

Which one of the following statements defines what we mean by a “hazardous area”?

An area where work or operations mean that it is dangerous to enter.

An area where a flammable gas atmosphere is, or may be, expected to be present.

An area that should be kept off limits to passengers.

Any compartment containing electrical equipment operating above 110 Volts.

Which one of the following statements most accurately defines the term “portable electrical equipment”?

Electrical equipment that can be lifted by one person.

Electrical equipment that is connected to the supply by a cable through a plug and socket.

Electrical equipment that can be carried by two persons.

Electrical equipment that can operate on dual voltage supplies.

Which one of the following would be the minimum current level above which an electric shock could be considered potentially fatal for to the average person?

Twenty-five milliamps (25 mA).

One hundred milliamps (100 mA).

Three amps (3 A).

Thirteen amps (13 A).

Which one of these is the main purpose of electrical cable insulation?

To prevent heat loss to the area around the cable.

To protect the conductors from mechanical damage.

To prevent current from flowing anywhere, other than through the conductors.

To protect the conductors in the event of a fire.

Which one of these is the most important effect of deposits of dirt, chemicals, or oil on electrical cables?

The cable insulation resistance will be reduced.

There will not be any effect.

The cable insulation resistance will be increased.

The cable sheath will become discoloured.

Which one of these statements best describes persons who should carry out electrical work on board ship?

Only the designated electrical officer.

Only those who are trained, experienced and therefore competent.

Only the designated electrical and engineering officers.

Any person nominated by the Chief Engineer.

With regard to an insulation resistance test on electrical equipment, which one of the following statements best describes where the insulation resistance should be measured?

Between each conductor and earth, and between each of the conductors.

Between each cable sheath and earth.

Between the ends of each conductor, and between the ends of the cable sheath for each conductor.

Between each conductor and the equipment frame or enclosure.

With regard to an insulation resistance test on electrical equipment, which one of the following statements gives the correct sequence for connecting and disconnecting the test leads?

Connect the earth lead first, before the live lead. Remove the live lead first, and the earth lead last.

Connect the live lead first, before the earth lead. Remove the live lead first, and the earth lead last.

Connect the earth lead first, before the live lead. Remove the earth lead first, and the live lead last.

Connect the live lead first, before the earth lead. Remove the earth lead first, and the live lead last.

With regard to work on electrical equipment, which one of the following statements best describes how equipment should be proved dead?

By using an approved voltage testing device or voltmeter at the point of isolation.

By using an approved multimeter at the point of work.

By confirming that the local starter no longer causes the equipment to run.

By using an approved voltage testing device or voltmeter at the point of work.

With regard to work on electrical equipment, which one of the following statements best describes how equipment should be safely identified?

By observing at the point of work that it starts/stops when its control circuit is operated.

By looking at the circuit diagrams on board ship.

By checking the labels at the point of work and in the control room.

By asking the Chief Engineer.

With regard to work on electrical equipment, which one of the following statements best describes how it can be ensured that equipment remains safely isolated?

By removing fuses.

By posting a caution notice anywhere that the equipment has been isolated, and locking off switches or removing fuses whenever possible.

By informing the engineer and deck officers on duty.

By disconnecting wiring or cables at the point of work.

With regard to work on electrical equipment, which one of the following statements best describes the term “isolated”?

Disconnected from any electrical supply, and physically separated from it by an adequate gap.

Switched off.

Switched off, with a warning notice posted.

Switched off, with the start button locked off.

With regard to work on electrical equipment, why is the use of multimeters not recommended for proving equipment dead?

It is too easy to have them on the wrong measurement scale, and in some cases this can also be dangerous.

Only analogue instruments should be used, and multimeters tend to be digital devices.

Multimeters can give incorrect readings if the batteries are nearly used up.

Multimeters tend to be less accurate.

With regard to work on electrical equipment, why should a special insulation resistance meter be used for checking insulation resistance, rather than a multimeter?

The insulation resistance meter applies a test voltage of 500 Volts which gives a more realistic test.

Multimeters cannot usually measure resistance.

Using multimeters can damage some equipment.

Multimeters can give incorrect readings if the batteries are nearly used up.

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