Welcome to the website where you can pass online the Seafarer Evaluation Training System (SETS) test on «EO2: Characteristics of Electrical Systems and Equipment». Practice like this will help you as a marine specialist improve your knowledge with the help of online studying and appraisal practice. SETS based on practical information and marine specialists experience.
SETS tests developed for evaluating seaman basic knowledge by company “Naval Education Services” is an evaluating online-tool, used for revealing any professional preparation needed in specific fields of knowledge, defined by STCW Section A-V/1-2.
SETS tests have proven themselves as good tools for the selection and recruitment process, as well as advancing the level of knowledge of the current officers and crew.
Current test contains SETS questions in area «EO2: Characteristics of Electrical Systems and Equipment». Those questions can be used for competence verification specialist capable of preventing accidental situations related with transporting safety, or also for self-examination.
«EO2: Characteristics of Electrical Systems and Equipment» subject includes theoretical and practical information about advanced training for work on any type of vessel. This test comprehensively assesses your understanding of the electrical systems found in modern maritime vessels. It evaluates your knowledge of power generation, distribution and protection equipment. A significant portion of the exam is dedicated to the practical application of safety procedures for high-voltage systems. You will be required to demonstrate knowledge of troubleshooting and maintenance protocols for critical equipment. The test includes scenarios focusing on emergency response and failure modes within a ship’s electrical network. It verifies your competency in interpreting electrical diagrams and schematics specific to marine engineering. Questions will cover the characteristics and management of advanced equipment like generators, switchboards and propulsion drives. Successful completion of this assessment validates the advanced training required to work on the electrical systems of any type of vessel.
On this site SETS on the subject «EO2: Characteristics of Electrical Systems and Equipment» contains 270 questions you need to answer with no possibility to go back to previous question. Therefore, we recommend carefully reading each question and making decision with no hurry. In case you have some difficulty answering, you have also possibility to request a hint.
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Amount of questions: 270.
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What is the maximum number of 50 W bulbs you would recommend to be connected to a 220 V outlet fused with a 10 A fast blowing fuse?
20.
46.
44.
22.
What is the normal output voltage range of an insulation meter?
Between 200 and 300 Volts.
Between 200 and 500 Volts.
Between 500 and 800 Volts.
Between 250 and 1 000 Volts.
Which of the following statements is correct?
The resistance of a human body increases in a humid atmosphere.
The resistance of a human body is unaffected by humidity.
The resistance of a human body decreases if the applied voltage is increased.
The resistance of a human body is unaffected by applied voltage.
What is the normal resistance of the human body?
4 000 Ohms at 25 Volt.
5 000 Ohms at 25 Volt.
2 000 Ohms at 25 Volt.
5 000 Ohms at any voltage.
Can a current as low as 25 mA kill a human being?
Yes, but only if applied for a long period.
Yes, but only if the applied voltage is high enough.
Yes, but only from an AC source.
No, not a fit healthy person.
How many ohms make one megohm?
100 000.
1 000 000.
1 000.
10 000 000.
Express 125 mA in amperes?
0,00125 A.
1,25 A.
0,125 A.
0,0125 A.
A ship’s electrical system is usually the so-called “insulated neutral” type. What does this means?
The system’s zero voltage point is connected to the frame of the generator.
The system is totally insulated from the ship’s hull.
The system is totally insulated from the ship’s 220 V distribution system.
The system does not have a neutral point.
How will an earth failure be noticed in an insulated distribution system?
The fuse in the faulty circuit will blow.
The fuse located in the system’s neutral point will blow.
The voltage will drop in proportion to the earth leakage.
The system insulation meter will indicate a drop in resistance.
What is the purpose of a preference load tripping system?
To disconnect important equipment before a short circuit can cause damage.
To re-connect essential equipment after a black out.
To disconnect non-essential equipment in case of generator overload.
To trip a generator if the load becomes too large.
What is the purpose of an instrument transformer installed on the generator main bus-bars?
To measure the generator output voltage.
To measure the generator output current.
To measure the temperature of the bus-bar.
To prevent bus-bar overload.
What will happen if the connections between an ammeter and an instrument transformer located on the generator main bus-bars are disconnected?
The ammeter will go to zero.
The ammeter will go to maximum.
The ammeter will read zero and the instrument transformer will quickly become over heated.
Nothing will happen.
What does the symbol in the diagram show?
A PNP transistor.
A thyristor.
A NPN transistor.
A double pole transistor.
What does the symbol in the diagram show?
A zener diode.
A thyristor.
A bridge rectifier.
A diode.
What does the symbol in the diagram show?
A zener transistor.
A rectification diode.
A zener diode.
A regulating diode.
What can the component showed in the picture be used for?
As a frequency stabiliser.
As a voltage stabiliser.
As a temperature stabiliser.
As a light emitter.
What does the symbol show?
A light absorber.
A light emitting diode.
A heat absorber.
A heat measurer.
What does the symbol in the diagram show?
A circuit that is connected to a DC source.
A circuit that is not allowed to be earthed.
A circuit that is connected to earth.
A circuit that is connected to earth if a short circuit occurs.
What does the symbol in the picture show?
A capacitor.
A battery (single cell).
An AC power supply.
A switch.
What does this symbol show?
An OR gate.
A NOR gate.
A NAND gate.
An AND gate.
What does the symbol in the picture show?
An OR gate.
A NOR gate.
A NAND gate.
An AND gate.
What does the symbol in the picture show?
A double amplifier.
A latch.
A lock amplifier.
A latch rectifier.
What is the total resistance of the three resistors shown in the diagram?
150 Ohm.
250 Ohm.
300 Ohm.
200 Ohm.
What will the total resistance of the four resistors shown in the diagram?
200 Ohm.
250 Ohm.
300 Ohm.
400 Ohm.
Calculate the current “I” in the diagram?
100 mA.
0,01 mA.
1,0 A.
0,01 A.
What is the total resistance of the two resistors shown in the diagram?
400.
300.
200.
100.
What resistance does RS have to be for the combined resistance of the circuit to be 50 Ohm?
100 Ohm.
200 Ohm.
20 Ohm.
50 Ohm.
What is the function of the circuit shown in the diagram?
A full wave rectifier.
A half wave rectifier.
A zero point meter.
A transformer balance adjuster.
From the sample diagrams shown, choose the correct voltage waveform measured across the load.
1.
2.
3.
4.
What is the symbol in the picture show?
A NPN diode.
A PNP diode.
A PNP transistor.
A NPN transistor.
Which of the following four materials is the best electrical conductor?
Copper.
Brass.
Silver.
Steel.
An electrical heater is marked 220 V, 4 400 W. What is the resistance of the heater?
220 Ohm.
11 Ohm.
22 Ohm.
110 Ohm.
Two electrical heaters both marked 220 Volt and 2 200 W are connected in series to a 220 Volt supply with a 10 A fuse. What will happen?
The fuse will blow.
The heaters will produce twice their normal heat output.
The heaters will produce half of their normal heat output.
The heaters will be damaged as the voltage is different from their marked voltage.
When is it necessary to take into the consideration the internal resistance of a multi-meter?
When the resistance in the circuit to be measured is very high.
When the resistance in the circuit to be measured is very low.
When the frequency of the circuit become very high.
It is not necessary to consider multi-meter resistance.
Which of the following components can be used as an voltage stabiliser?
A coil.
A PNP transistor.
A zener diode.
An OR gate.
In the diagram, if E is set to 15 Volt, Uz will be 12 Volt. What will Uz become if E is increased to 20 Volt?
17 Volt.
16 Volt.
12 Volt.
20 Volt.
What is the circuit shown here used for?
As an amplifier.
As an rectifier.
As a voltage regulator.
To measure a DC current.
Choose the correct Boolean equation for the circuit shown:
E = ((A*B) + (C*D)).
E = ((A+B) + (C*D)).
E = ((A+B) * (C+D)).
E = ((A*B) * (C*D)).
Choose the correct Boolean equation for the circuit shown:
E = ((A+B) * (C+D)).
E = ((A*B) * (C*D)).
E = ((A+B) + (C+D)).
E = ((A*B) * (C+D)).
What is component X called?
A converter.
An integrator.
An invertor.
A rectifier.
What does the symbol in the diagram show?
The windings of a three pole DC shunt motor.
The windings of a three phase AC “Y” connected motor with earthed neutral.
The windings of a three pool DC “Y” connected motor.
The windings of a three phase “D” connected motor.
What does this symbol show?
A three phase “Delta” connected motor.
A three phase DC connected motor.
A three phase “Y” connected motor.
A three phase compound AC motor.
What is the purpose of the circuit shown in the diagram?
To light the lamp when the coil is de-activated.
To operate the relay coil A with buttons 1 and 2.
To prevent relay coil A becoming over-heated.
To change direction of the motor connected to coil A.
Choose the correct Boolean expression for the output at D.
D = A + B + C.
D = A + (B * C).
D = A * B * C.
D = A – (B * C).
Which formula gives the correct Boolean expression for the component shown?
1.
2.
3.
4.
Which option gives the correct output for the gate shown?
1.
2.
3.
4.
Which option gives the correct output for the gate shown?
1.
2.
3.
4.
Which option gives the correct output at A?
0 minus 1.
0.
0 times 0.
1.
What will happen when switch D is closed?
Relay A will activate.
Lamp E will de-activate.
Relay B will de-activate.
Lamp E will activate.
What conditions are needed for relay A to be activated?
Relay B activated and switch F closed.
B de-activated and switch F and G closed.
Switch G open and relay B activated.
Switch F closed and relay B activated.
How can lamp E be turned on?
By closing switch D.
By closing switch C.
By closing switch D and switch F at the same time.
Lamp E cannot be turned on.
How will coil C be activated?
When both D and E are closed.
When D, E and F are closed.
When E and A are closed.
When A and B are closed and either D or E are closed.
When will coil C be activated?
When E is closed and D is open.
When E is closed and relay F activated.
When relay F is activated.
When A and B is closed and D is open.
What does the symbol “A” represent?
A differential amplifier.
An operational amplifier.
A summing amplifier.
A flip-flop amplifier.
What is the function of the circuit shown here?
A digital summarizer.
A summing operational amplifier.
An integrating operational amplifier.
A differential amplifier.
What is the purpose of the circuit shown here?
To measure low frequent current.
To measure the resistance of RL.
To measure voltage E.
To calibrate resistance Rv.
If the resistances RL and Rv are equal, what will be the voltage Vm? (Assume R1 = R2).
E divided by R1 + R2.
E = Vm.
(R1*R2) + (RV*RL).
Zero.
What does the symbol shown here represent?
An American standard NAND gate.
A European standard AND gate.
A European standard NAND gate.
An American standard NOR gate.
What does the symbol shown here represent?
An American standard invertor.
A European standard converter.
An American standard NOR gate.
A European standard OR gate.
What does this symbol represent?
A European standard NOR gate.
An American standard NAND gate.
A European standard NAND gate.
An American standard NOT gate.
What does this symbol represent?
An American standard AND gate.
A European standard AND gate.
An American standard NOR gate.
A European standard NAND gate.
What will be the output “A” in this circuit?
0.
0 + 0.
1 * 0.
1.
The specific gravity of the cells in a lead acid battery for the emergency generator is found to be 1,250. What action would you take?
Top up with water.
Refresh with the addition of new acid.
Check the charging system and if possible increase the charging rate.
No action is required.
Complete the sentence. Ships normally use an AC insulated neutral distribution system because:
It limits fault current.
An earth failure on one phase will not cause protective devices like fuses and circuit breakers to trip.
It reduces cable size.
It reduces switch gear ratings.
What type of probe is most suitable to measure the main engine exhaust temperature?
A PT100 (Platinum wire resistance) probe.
A T802 (Thermistor) probe.
A NiCr/NiAl-type K (Thermocouple) probe.
A mercury thermometer probe.
Why should an electronic digital meter be used to measure voltage in electronic circuits?
Because it’s easier to read.
Because it’s not affected by interference.
Because the voltage for electronic circuits can only be sensed by an electronic meter.
Because the input resistance of the meter is high enough not to affect the circuit under test.
What type of electrolyte is used in a nickel cadmium battery?
Dilute sulphuric acid.
Distilled water.
Potassium hydroxide solution.
Dilute hydrochloric acid.
In the “Ward/Leonard” method of DC motor speed control, how is the motor direction changed?
Reversal of generator polarity.
Reversal of motor field polarity.
By reversal of the rotation of the generator.
By switching the motor armature connections.
A flat lead acid battery can be revived by:
Filling with dilute sulphuric acid and trickle charging.
Adding “battery restorer“.
Adding distilled water.
Trickle charging.
Sulphation in a lead acid battery occurs as a result of:
Lack of trickle charging.
Incomplete charging.
Heavy discharging.
Fast charging.
What safety protection measure should be taken when connecting a multimeter to an unknown voltage source?
Set the multimeter to DC.
Set the multimeter to AC.
Set the multimeter to AC and highest voltage range.
Fast charging.
Which of the four alternatives shown gives the correct voltage output across component C when a step change in voltage is applied to the circuit?
A.
B.
C.
D.
Which of the four alternatives shown gives the correct voltage output across component L when a step change in voltage is applied to the circuit?
A.
B.
C.
D.
What is a diode?
A conductor.
A semi-conductor.
An insulator.
A part conductor..
Which two symbols in boxes A to D have the same function?
A.
B.
C.
D.
The state of charge of a lead acid battery is best indicated by:
Its ampere hour capacity.
An individual cell voltage.
Its total cell voltage.
The specific gravity of the electrolyte.
The basic unit of measurement of inductance is the:
Ohm.
Henry.
Farad.
Coulomb.
Battery rooms must be ventilated because it:
Prevents sulphation during discharge.
Supplies oxygen.
Dissipates explosive gases.
Prevents formation of moisture and condensation.
What kind of values can change continuously? Pressure and temperature are examples.
Digital values.
Humpless values.
Binary values.
Analog values.
Which one of the following devices uses the principle of electromagnetic induction?
A rectifier.
A transistor.
A transformer.
A rheostat.
What happens in a circuit when the voltage remains constant and the resistance increases?
The current decreases.
The current increases.
The current remains the same.
The current increases by the square of the increase in resistance.
Electric current is defined as the flow of electrons through a conductor. This is measured as:
Voltage.
Resistance.
Inductance.
Amperage.
One kilo-watt is equal to:
1,25 horse power.
1,34 horse power.
1,50 horse power.
2,00 horse power.
A horse-shoe magnet has:
3 poles.
4 poles.
2 poles.
No poles.
What kind of device measures pressure and converts it to an electrical signal?
A transducer.
A reducer.
A transformer.
A pressure rectifier.
A micro-processor is:
Another name for a computer.
A CPU integrated circuit.
Another name for a calculator.
A computer’s random memory.
What is the purpose of the capacitors used across the output of a DC power supply?
They act as a permanent load.
They prevent overload.
They filter out ripple.
They increase the output frequency.
The resistance in a wire decreases if:
The temperature of the wire increases.
The cross-sectional area of the wire increases.
The length of the wire increases.
The applied voltage decreases.
Which of these materials can be used to insulate magnetic flux?
Ceramic.
Rubber.
None of these.
Porcelain.
What is the main difference between a relay and a contactor?
A contactor is designed to handle heavier loads.
A relay is series connected but a contactor is parallel connected.
A contactor is series connected but a relay is parallel connected.
A relay can only operate with DC voltage but a contactor can operate with both DC and AC.
Voltage multiplied by current equals:
Resistance.
Capacity.
Power.
Efficiency.
If the resistance of a circuit doubles while the applied voltage remains constant, the current will be:
Doubled.
Halved.
Remain the same.
Quadrupled.
What is the voltage across A and B?
6 volts.
18 volts.
24 volts.
12 volts.
What is the voltage across A and B?
6 volts.
12 volts.
18 volts.
-6 volts.
What is the current I3?
I1-I2.
I1.
I1+I2.
I2.
This diagram shows the characteristics of a:
Diode.
Transistor.
Zener diode.
Thyristor.
This symbol represents a:
PNP transistor.
Field effect transistor.
Thyristor.
Diac.
This drawing shows the structure of a:
FET transistor.
Diode.
Bipolar transistor.
Light activated SRC.
This drawing shows the structure of a:
PNP transistor.
Flip-flop gate.
Thyristor.
Zener diode.
What is component number 2?
A thyristor.
A diac.
A triac.
A FET transistor.
What is component number 3?
A junction diode.
A diac.
A triac.
A FET transistor.
What is the function of component number 1?
To regulate the capacity over the triac.
To lower the inductance across resistance RL.
To regulate the firing of the diac diode.
To limit the voltage across resistance RL.
What is this circuit used for?
To test the back firing of the triac.
To test the opening voltage across the diac.
To regulate the power across resistance RL.
To regulate the voltage across component number 3.
An ideal operational amplifier is characterised by:
Infinite input impedance.
Zero output impedance.
Infinite bandwidth.
All the other options.
Which of the following statements is most correct for a resistor?
An increase in temperature varies the resistance.
An increase in temperature has no effect on resistance.
An increase in temperature decreases resistance.
An increase in temperature increases resistance.
TTL is the abbreviation for a family of:
Integrated analog circuits.
Integrated digital circuits.
Integrated amplifying circuits.
Integrated differential circuits.
A triac circuit is used to regulate the brightness of a 220 V 60 W bulb. What is the advantage of this circuit?
The power losses are almost zero.
The bulb will give about 10 % more light.
The bulb will last about 30 % longer.
The bulb will produce 30 % less heat.
What is this component shown called?
An integrated rectifier.
A diode.
A transistor.
A capacitor.
What is the purpose of the lines on this component?
To identify the type of component.
To indicate the resistance and the resistance variance of the component.
To indicate the resistance of the component.
To indicate the maximum inductance which can be applied.
What type of component is this?
A resistor.
A capacitor.
A variable resistor.
A diode.
What is the name and application of this component?
A transistor for high power.
A high frequency diode.
A diode for high power applications.
A diode for light emitting applications.
What is the name of this component?
A high power diode.
A low power diode.
A high power transistor.
A high power half-wave rectifier.
Which statement is correct?
The TTL family of integrated circuits consume less current than the CMOS family of integrated circuits.
A CMOS integrated circuit is a non-digital switching system.
A TTL integrated circuit has a low processing speed.
The CMOS family of integrated circuits consume less current than the TTL family of integrated circuits.
What is the normal operating voltage of a TTL circuit?
12 volts.
5 volts.
8 volts.
24 volts.
What is this component?
An NPN transistor.
A P channel junction transistor.
An N channel junction transistor.
A P channel diode.
Which of the two transformers will provide an electrically insulated voltage E2 from the source voltage E1?
Number 1.
Number 2.
Neither.
Both.
Which of the two transformers can be used for regulating the size of voltage E2?
Number 1.
Number 2.
Both.
Neither.
Which of the two transformers are safer for regulating the voltage E2 in order to avoid electrocuting?
Number 1.
Number 2.
Both the same.
Neither.
In both circuits Voltage E is the same and all resistors R have the same value. In which circuit will the current be greater?
Circuit 1.
Circuit 2.
Both circuits will have the same current value.
The currents will be the same but the Voltage will be higher in 1.
Voltage form number 2 represents the output from a DIAC in a DIAC/TRIAC voltage regulator. What is the voltage used for?
To close the TRIAC.
To fire a light diode.
To fire the TRIAC.
To reverse the TRIAC voltage.
The pressostat shown in the picture controls the cut-in/cut-out of a pump. To what part of the pump’s electric motor would this be connected?
The main contactor.
The timer.
An auxiliary relay.
An overload relay.
What is the electrical function of the pressostat shown here?
Pressure to open contact.
Pressure to close contact.
Pressure to cross-connect contact.
Pressure to either close contact or open contact depending on how it is connected.
In this schematic diagram of a fluorescent lamp, in what location is the BALLAST fitted, if (1) and (2) are the supply terminals?
Between points 3 and 4.
Between points 5 and 6.
Between points 7 and 8.
Between points 9 and 1.
Between which points on this schematic diagram of a fluorescent lamp is the STARTER fitted?
Between points 3 and 4.
Between points 5 and 6.
Between points 7 and 8.
Between points 9 and 1.
In this schematic diagram of a fluorescent lamp, through which points is the electric current absorbed by the lamp during NORMAL operation (lighting)?
Through points 3 and 4.
Through points 5 and 6.
Through points 7 and 8.
Through points 3 and 8.
What is item No 11 called, shown here in this fluorescent lamp assembly?
The starting box or switching box.
The base.
The lamp fitting or holder.
The lamp body or lamp box.
What is shown by item No 3 on this electric motor?
Shaft sleeves.
Ball bearings.
Dust throwers.
Seals.
What is shown by item No 5 on this electric motor?
The outer casing.
The ventilation air passage grids.
The motor cover.
The inspection plates.
A battery of dry cells consists of 8 cells connected in series. Each cell has an EMF of 1,5 Volt and an internal resistance of 0,5 Ohm. If the cells are connected to a resistance of 1,2 Ohm, what current flows?
1,8 Ampere.
2,3 Ampere.
2,8 Ampere.
3,1 Ampere.
What is the resistance of a heating element of 2 kWatt, 220 Volt?
24,2 Ohm.
9,09 Ohm.
44 Ohm.
11 Ohm.
Determine the resistance of three resistors connected in STAR in a resistance box with 3 terminals? Resistance AB = 20 Ohm, resistance BC = 30 Ohm, resistance CA = 40 Ohm.
R1 = 15 Ohm, R2 = 5 Ohm, R3 = 25 Ohm.
R1 = 10 Ohm, R2 = 18 Ohm, R3 = 22 Ohm.
R1 = 12 Ohm, R2 = 8 Ohm, R3 = 22 Ohm.
R1 = 10 Ohm, R2 = 10 Ohm, R3 = 30 Ohm.
In oil type circuit breakers, what is the purpose of the oil?
To act as insulation.
To smother the arc.
The release of hydrogen gas in the oil will extinguish the arc.
All of the options.
In the worst case, an electric shock of as low as 15 milli-amps will:
Be totally harmless.
Give you a faint shock.
Burn your skin.
Be fatal.
What will happen when an earth fault occurs on one line of an insulated distribution system?
The line will short circuit with the earth and the line fuse trips.
The system will be in overload and both line fuse trip.
No fuses will trip, the system is isolated from the earth.
The opposite line fuse will trip due overload.
A single phase motor has a full load current of 28 A. What will be the rating of the branch fuses?
34 Amps.
56 Amps.
63 Amps.
112 Amps.
A voltmeter with 5 000 ohm internal resistance reads 10 volts at full scale. What resistor needs to be put in series to increase its range to 150 volts?
7 500 Ohm.
35 000 Ohm.
70 000 Ohm.
165 000 Ohm.
The low voltage side of a welding transformer has two turns and delivers 300 A. If the primary side has 30 turns, how much current flows through it?
10 Amps.
15 Ampere.
20 Amps.
30 Amps.
Two 30 Ohm resistors are connected in parallel. What is their combined resistance?
15 Ohm.
30 Ohm.
20 Ohm.
60 Ohm.
An electric appliance takes 2 500 Watt. The electric current is 15 Ampere. What is the resistance of the load?
8,2 Ohm.
9,4 Ohm.
10,5 Ohm.
11,11 Ohm.
How many diodes are there in a single phase full bridge rectifier?
Two.
Three.
Four.
Six.
In an emergency insulation resistance readings lower than normal can be acceptable, but what would the allowable minimum be?
0,5 Meg Ohm.
1,0 Meg Ohm.
5,0 Meg Ohm.
10,0 Meg Ohm.
What voltages are accredited standard secondary voltages for voltage transformers?
240 Volt and 220 Volt.
220 Volt and 110 Volt.
380 Volt and 220 Volt.
230 Volt and 120 Volt.
Current transformers supply ampere meters and the current operated coils of instruments with a standard current of either:
2 or 1 Amps.
5 or 1 Amps.
20 or 5 Amps.
20 or 5 milli-amps.
What is the purpose of the cable gland in addition to providing a watertight seal?
To provide a gas tight seal.
As bulkhead or penetrating plate reinforcement.
To allow minor sliding movements of the cable.
To maintain the mechanical properties of the cable.
What is the purpose of the part circled red?
To protect the motor from water.
To cover the fan of the motor.
To cover the lubrication inlet.
To cover the speed regulator.
A Wheatstone Bridge is used to measure an unknown resistance in relation to what?
A voltage drop.
A current imbalance.
Kirchoff’s Laws.
A known resistance.
What is power?
The mount of work done.
The rate of energy dissipation.
The capacity for doing work.
The generated current.
Which of the following is not a requirement for the Navigation light distribution board?
Double pole switch.
Always supplied from batteries.
Audible and visual lamp failure alarm.
Location on the Bridge.
What are valence electrons?
Outer orbiting electrons.
Contained in the nucleus.
Orbiting electrons.
Positively charged electrons.
In one complete cycle of a single phase of alternating current how often is the voltage at zero?
Never.
Once.
Twice.
Three times.
How will the plastic insulation in a cable be affected if the temperature exceeds 100 degrees C?
The insulation is likely to be severely damaged.
Nothing as the insulation is designed to withstand more than 500 degrees C.
The life-span of the cable will be reduced in accordance with the conductor life span formula.
The insulation resistance is increased as the heat will remove any trace of humidity.
When will the resistance in a wire decrease?
When the temperature of the wire increases.
When the cross-sectional area of the wire increases.
When the length of the wire increases.
When the applied voltage decreases.
How will an earth failure be noticed in an insulated distribution system?
The fuse in the faulty circuit will blow.
The fuse located in the system’s neutral point will blow.
The voltage will drop in proportion to the earth leakage.
The system insulation meter will indicate a drop in resistance.
Why must each voltage system have it’s own earth fault lamps?
In case of failure of one set.
To accurately locate the earth fault.
To make tracing the earth easier.
Earth faults are not transmitted through the transformers.
In a fluorescent lamp what is used to improve the power factor?
Capacitor.
Mercury gas.
Coil.
Thyristor.
A ship’s electrical system is usually the so-called “closed insulation” type. What does this mean?
The system’s zero voltage point is connected to the frame of the generator.
The system is totally insulated from the ship’s hull.
The system is totally insulated from the ship’s 220 V distribution system.
The system does not have a neutral point.
In incandescent lights what is the filament constructed from?
Nickel.
Carbon.
Tungsten.
Chromium.
Why must both primary and secondary windings have independent earth leakage detection?
To accurately locate the earth.
There is no electrical connection between the two.
To allow for different leakage current levels.
Because of the difference in Voltages.
The size of any electrical conductor should be such that the voltage drop at full load will not exceed what percentage?
1 %.
2 %.
3 %.
4 %.
Which conductor would produce the greatest inductance?
Plain coiled.
Coiled with copper core.
Coiled multi strand.
Coiled with iron core.
In the formula e = B l ØSin. What does sin represent?
Average rotational velocity.
Cycles/second.
Maximum rotational velocity.
Instantaneous rotational velocity.
When using a Megger Tester to test equipment rated 440 Volt, what test voltage should you ensure that the instrument indicates?
250 volts.
500 volts.
750 volts.
1 000 volts.
Which law governs the relationship between potential difference and current?
Coulomb’s law.
Lenz’ law.
Ohm’s law.
Kirchoff’s current law.
How will an earth failure be noticed in an insulated distribution system?
The fuse in the faulty circuit will blow.
The fuse located in the system’s neutral point will blow.
The voltage will drop in proportion to the earth leakage.
The system insulation meter will indicate a drop in resistance.
Which of the following is most likely to cause an earth indication?
A switched off motor has developed a short circuit.
A deck fitting has been affected by seawater.
Emergency generator, which is on stand-by, has been splashed with seawater.
Earth fault on the navigation lights.
When using an ohmmeter to find a short circuit, which meter reading indicates the fault?
Infinity.
100 megohm.
1 megohm.
Zero.
At maximum voltage what angle is the conductor cutting the magnetic field?
0 degrees.
45 degrees.
90 degrees.
180 degrees.
A Wheatstone Bridge is a precision instrument used mostly to measure:
Capacitance.
Resistance.
Inductance.
Amperage.
Voltage multiplied by current equals what?
Resistance.
Efficiency.
Power.
Reactance.
When is an atom considered to be a positively charged ion?
When electrons are gained.
When electrons are lost.
When it has positive electrons.
When it has positive protons.
What is the required minimum Megger test reading for MCCB’S circuit breakers?
1-3 Megohm.
4-6 Megohm.
5-8 Megohm.
7-10 Megohm.
What term describes the effective value of an alternating current?
Mean.
Average.
RMS.
Peak.
Which measuring device should always be connected in series with a circuit?
Ohmmeter.
Ammeter.
Wattmeter.
Voltmeter.
What is the unit of magnetic flux?
Farad.
Henry.
Coulomb.
Weber.
How is a Voltmeter connected in a circuit?
In series.
In series with a resistance.
In parallel.
In parallel, combined with a resistance.
If a 2 kW heater is on for four hours, how much energy is used?
24 mJ.
28,8 mJ.
36,6 mJ.
40 mJ.
What do good insulators have in common?
Large number of electrons.
Positive electrons.
Stable atomic structure.
Negative nucleus.
In a non-reactive circuit which statement applies?
Impedance is greater than resistance.
Impedance is less than resistance.
Impedance is zero.
Impedance is equal to resistance.
Which law states that the sum of the potential differences is equal to the sum of the EMFs?
Coulomb’s Law.
Ohm’s Law.
Lenz’ Law.
Kirchoff’s Voltage Law.
What may happen if a Megger tester is used to measure the insulation in a circuit containing electronic components?
The Megger may give an indication on how much current the circuit will consume.
The components in the circuit may be destroyed.
The wrong internal resistance may be shown.
The connections between components will show a high insulation value.
What is the danger of fitting too high wattage lamps in flameproof fittings?
Seal could be damaged by extra heat.
Increase in surface heat of fitting.
Extra power could overload the cable.
Internal heat generated will damage the fitting.
When two masthead lights are fitted what is the required relationship between them?
Both must be at the same level.
Frd must be at least 4,5 metres higher than the aft.
Frd must be at least 2 metres higher than the aft.
Aft must be at least 4,5 metres higher than the frd.
When both a fuse and breaker are used on one circuit, when will the fuse blow?
A break in the motor winding.
A very high short circuit current.
Continuous moderately high over-current.
An earth fault.
Why is the battery maintenance of such importance?
To comply with the planned maintenance requirements.
The batteries are the last resort back-up system.
They are an item of survey equipment.
To ensure there is a continuity of supply to the navigation lights.
Which of these materials can be used to insulate magnetic flux?
Rubber.
Ceramic.
None of the other options.
Porcelain.
Which of the following is the most suitable for use as a magnet?
Stainless steel.
Soft iron.
Copper.
Nickel.
In series connected resistors which value remains constant?
Voltage.
Current.
Resistance.
Reactance.
How will the plastic insulation in a cable be affected if the temperature exceeds 100 degrees Celsius?
The insulation is likely to be severely damaged.
Nothing as the insulation is designed to withstand temperatures of more than 500 degrees Celsius.
The life-span of the cable will be reduced in accordance with the conductor life span formula.
The insulation resistance is increased as the heat will remove any trace of humidity.
In the worst case what would be the effect a 25 milli-amps electric shock?
Totally harmless.
Give a mild shock.
Burn the skin.
Could be fatal.
Two resistors of 6 ohm & 3 ohm are connected in parallel across an EMF of 12 V, what is the circuit current?
2 A.
6 A.
3 A.
9 A.
If a p. d. of 24 V exists across a 15 Ohm resistor what is the current?
0,6 amps.
3,6 amps.
1,2 amps.
1,6 amps.
If a 100 metre length of 1,25 mm dia. wire has a resistance of 30 Ohm, what length of the same wire of 0,75 mm dia. will have a resistance of 25 Ohm?
35 metres.
20 metres.
25 metres.
30 metres.
What danger is associated with excess shaft magnetism?
Failure of the generator to self excite.
Damage to shaft bearing surfaces.
Arcing at commutator.
Insulation breakdown.
Using lead/acid batteries what is the minimum number of cells required to produce 24 V?
12.
24.
6.
16.
Which law states that the sum of currents arriving at a junction is equal to the sum of currents leaving the junction?
Ohm’s Law.
Lenz’ Law.
Kirchoff’s Current Law.
Faraday’s Law.
What is the unit for inductance?
Henry.
Weber.
Farad.
Coulomb.
What is the electrolyte in a conventional lead/acid battery?
Distilled water.
Dilute Sulphuric acid.
Dilute Hydrochloric acid.
Potassium hydroxide.
What happens to the current if the resistance of a circuit doubles while the applied voltage remains constant.
Doubled.
Halved.
Remains the same.
Quadrupled.
What will happen when an earth fault occurs on one line of an insulated distribution system?
The line will short circuit with the earth and the line fuse trips.
The system will be in overload and both line fuses trip.
No fuses will trip, the system is isolated from the earth.
The opposite line fuse will trip due overload.
What is the maximum allowable temperature for normal Class A insulation type?
45 degree C.
55 degree C.
80 degree C.
105 degree C.
What is the purpose of an instrument transformer installed on the main bus bars?
To measure the generator output voltage.
To measure the generator output current.
To measure the earth leakage.
To prevent bus-bar overload.
What is the danger of naked lights in the battery locker?
Reaction with the gases to form a toxic mixture.
They may damage the battery casings.
The batteries give off highly flammable hydrogen gas.
The batteries give off hydrogen sulphide making the air explosive.
What causes the EMF variation in an AC alternator?
Flux density.
Changing polarity.
Velocity of conductor cutting flux.
Component of velocity at 90° to flux.
What is energy?
Capacity to carry out work.
Rate of doing work.
Amount of work done.
Transfer of power.
Give the reason why shore power and ship’s power should never be run in parallel?
Ship’s supply is in STAR, shore supply is in DELTA.
The shore frequency is rigid, the ship’s frequency is not.
No common earth is available.
Voltage drop from shore is different from the ship.
How is an Ammeter connected in a circuit?
In series.
In series with a resistance.
In parallel.
In parallel with a resistance.
Why do ships normally use an AC insulated neutral distribution system?
It limits fault current.
An earth failure on one phase will not cause protective devices like fuses and circuit breakers to trip.
It reduces cable size.
It reduces switchgear ratings.
What produces an induced EMF?
Change in voltage.
Change in flux linkage.
Change in current.
Change in resistance.
What is the wire made from in an HRC fuse?
Platinum.
Tungsten.
Silver.
Nickel.
In an emergency, what would be the lowest acceptable insulation resistance readings?
0,5 Meg Ohm.
1,0 Meg Ohm.
5,0 Meg Ohm.
10,0 Meg Ohm.
What is the normal output voltage range of an insulation meter?
Between 200 and 300 Volts.
Between 1 000 and 10 000 Volts.
Between 500 and 1 000 Volts.
Between 400 and 500 Volts.
What is the purpose of the cable gland in addition to providing a watertight seal?
To provide a gas tight seal.
As bulkhead or penetrating plate reinforcement.
To allow minor sliding movements of the cable.
To maintain the mechanical properties of the cable.
Why should an earth failure be checked and cleared as soon as possible?
It may damage the monitoring instruments.
There may be a circulating current around the vessel’s hull.
The Unattended Machinery Space (UMS) certificate may be withdrawn.
A conflicting earth failure may occur and cause fuses to blow.
What kind of device measures pressure and converts it to an electrical signal?
A transducer.
A transponder.
A transformer.
A transceiver.
What law states that induced EMF always opposes the change producing it?
Lenz.
Faraday.
Fleming.
Coulomb.
What is impedance?
Total resistance in an electrical circuit.
Resistance provided by the cable in an electrical circuit.
Induction of an electrical circuit.
Induced EMF of a circuit.
Which of the following four materials is the best electrical conductor?
Copper.
Brass.
Silver.
Steel.
How much energy is dissipated when a 2A current is passed through a 50 ohm resistor for 3 minutes?
24 kJ.
30 kJ.
33,3 kJ.
36 kJ.
What is the unit for energy?
Watt.
Coulomb.
Joule.
Ohm.
Which statement is true for induced EMF?
Always equal to the current.
Always resists change in current.
Always assists change in current.
Is a function of resistance.
How can a Voltmeter measure a variety of voltage values?
By connecting a shunt in series.
By connecting a shunt in parallel.
By connecting a capacitor in series.
By connecting a capacitor in parallel.
What do wire size numbers indicate?(e. g. sizes 10, 12 etc).
Wire section in square millimetres.
Wire outside diameter in millimetres.
Retrogressive numbering in “AWG“.
Progressive numbering in Amps.
In parallel connected resistors which value remains constant?
Impedance.
Reactance.
Voltage.
Current.
What gases are present in the modern incandescent lamp?
Vacuum.
Argon and Nitrogen.
Argon and Neon.
Neon and Nitrogen.
What is the advantage of a delta-star wound transformer?
Can transform higher loads.
Allows cycle changing.
Allows an earthed secondary winding.
Allows an earthed primary winding.
What are ideal conditions for taking insulation test readings of a motor or alternator?
Hot after stopping.
Cooled down to hand-warm.
Cooled down to ambient temperature.
Running.
Which of the following would you expect to find at the main switchboard?
Insulated rubber matting.
Insulated grab rails.
Suitable extinguisher.
All of the other options.
Using Fleming’s Right Hand Rule what does the thumb indicate?
Direction of current in the conductor.
Direction of the magnetic flux.
Direction of movement of the conductor.
Direction of the excitation current.
What governs induced EMF in a conductor?
Flux density.
Rate of cutting flux.
Rate of change of magnetic flux.
Magnetic strength.
Two resistors of 6O ohm & 3O ohm are connected in parallel across an EMF of 12 V, what is the effective resistance?
20 ohm.
4,50 ohm.
90 ohm.
60 ohm.
Why are Arc chutes fitted in circuit breakers?
To extinguish the arc and prevent carbon formation.
To isolate the breaker segments so the arc does not blow over.
To control the temperature and molecular structure of the arc.
To confine the arc, control its movement and provide rapid cooling.
In the formula e = B l ØSin. What does “e” represent?
Maximum voltage.
Average voltage.
Instantaneous voltage.
RMS voltage.
For value 0 – max in the AC sin wave how far does the rotating vector (phasor) travel?
180 deg.
90 deg.
270 deg.
360 deg.
In a purely resistive circuit what is the phase difference between voltage and current?
0 deg.
90 deg.
180 deg.
45 deg.
The ratio of active power to apparent power is known as?
RMS voltage.
Power factor.
Angle of phase difference.
Circuit inductance.
Why is a ballast resistor fitted in fluorescent lamps?
Pre heat the electrodes.
Provide high starting voltage.
Stabilize current and power.
Performs all of these functions.
In one cycle of 3-phase AC how often is voltage at peak value?
Six times.
Twice.
Three times.
Always.
In an incandescent lamp how much of the energy is converted to light?
80 %.
60 %.
40 %.
20 %.
In internal alleyways what is the light spacing regulation?
Lights spaced at 1,5 × alleyway height.
Lights spaced every 2 metres.
Lights spaced at 2 × alleyway height.
Lights spaced every 2,5 metres.
On an electrical drawing what symbol represents impedance?
R.
I.
Z.
L.
How will an earth fault be noticed in an insulated distribution system?
The fuse in the faulty circuit will blow.
The fuse located in the system’s neutral point will blow.
The voltage will drop.
The system insulation meter will indicate a drop in resistance.
In what situation is Induced EMF given by the formula e = Blv?
When a conductor rotates in a magnetic field.
When a single conductor cuts a magnetic field in a straight line.
When a conductor is rotated between opposing magnets.
When a magnet is rotated in a coiled conductor.
What happens in a circuit when the voltage remains constant and the resistance increases?
The current decreases.
The current increases.
The current remains the same.
The current increases by the square of the increase in resistance.
What would be the SG of a fully charged battery?
1,12.
1,2.
1,28.
1,36.
In the AC sin wave what is the periodic time?
Time for zero to max voltage.
Time for zero to zero voltage.
Cycles/second.
Time for one complete cycle.
What is the amplitude of the AC sin wave?
Peak value.
Cycle length.
Cycles/second.
Phasor value.
What is the normal output voltage range of an insulation meter?
Between 200 and 300 Volts.
Between 200 and 500 Volts.
Between 500 and 800 Volts.
Between 400 and 500 Volts.
Which of the following is a requirement for the Navigation lighting distribution board?
Fuse located on the main switchboard.
Alarm must sound in the engine room.
An alternate supply must be available.
Indicator lamps must be in series with the navigation light.
What units is impedance expressed in?
Henry.
Ohm.
Farad.
Weber.
Two resistors of 6O ohm & 3O ohm are connected in parallel across an EMF of 12 V, what is the current in each resistor?
2 A & 4 A.
3 A & 6 A.
1 A & 2 A.
0,66 A & 1,33 A.
In oil type circuit breakers, what is the purpose of the oil?
Acts as insulation.
To smother the arc.
To release hydrogen gas in the oil will extinguish the arc.
All of the other options.
Induced EMF is out of phase with current by what degree?
0 degrees.
180 degrees.
90 degrees.
60 degrees.
On an electrical drawing what symbol represents Inductance?
F.
I.
R.
L.
What is a Clamp meter used for?
To measure current in a single cable.
To measure cable resistance.
To measure current in a three phase cable.
To measure cable voltage.
If the effective resistance of a circuit is 8 ohm and current from source is 1,5 A what is the EMF?
6 V.
24 V.
12 V.
9 V.
What is a multi meter used for?
To measure resistance.
To measure voltage and resistance.
To measure voltage, resistance and current.
To measure voltage and current.
If magnet pole faces are 3 cm × 4 cm and have flux density of 0,417 T, what is the flux?
0,5 mWb.
0,4 mWb.
0,7 mWb.
0,55 mWb.
Except when used as bus-bars, which conductor number (AWG), or larger should always be stranded?
No 6 AWG.
No 8 AWG.
No 10 AWG.
No 12 AWG.
How does the RMS voltage compare to peak voltage?
0,666 of peak value.
0,707 of peak value.
0,805 of peak value.
0,777 of peak value.
In a three-phase system why is a resistor fitted in series with the earth detection lights?
To limit the earth current.
To protect the earth lights.
To provide an easier path for the earth current.
To lower the voltage at the earth lights.
What is the unit of lighting intensity?
Lumen.
Candela.
Angstrom.
Lambert.
A voltmeter with 5 000 ohm internal resistance reads 10 volts at full scale. What resistor needs to be put in series to increase its range to 150 volts?
7 500 Ohm.
35 000 Ohm.
70 000 Ohm.
165 000 Ohm.
An electrical heater is marked 220 V, 4 400 W. What is the resistance of the heater?
220 Ohm.
11 Ohm.
22 Ohm.
110 Ohm.
What is the unit for power?
Ohm.
Watt.
Coulomb.
Joule.
Why should an earth failure be checked and cleared as soon as possible?
It may damage the monitoring instruments.
There may be a circulating current around the vessel’s hull.
The Unattended Machinery Space (UMS) certificate may be invalid.
A conflicting earth failure may occur and cause fuses to blow.
What problem can arise from auto starting electric equipment?
Overload the generator prime mover.
Trip preferential trips.
Trip reverse power trip.
Over speeds the generator prime mover.
What law determines the direction of induced EMF?
Faraday.
Fleming.
Lenz.
Weber.
How can an Ammeter measure a variety of current values?
By connecting a shunt in series.
By connecting a shunt in parallel.
By connecting a capacitor in series.
By connecting a capacitor in parallel.
Which one of the following devices uses the principle of electromagnetic induction?
A variable capacitor.
A transistor.
A transformer.
A rheostat.
What is the continuity resistance of a heating element of 2 kWatt, 220 Volt?
24,2 Ohm.
9,09 Ohm.
44 Ohm.
11 Ohm.
What would a clamp type ampere meter read if clipped around a 3-core cable known to carry 100 Amps to a 3-phase electric motor?
100 Amps.
33,33 Amps.
300 Amps.
0 Amps.
With reference to a magnet what is Hysteresis?
Magnetic strength in relation to current.
Lag of flux compared to field strength.
Permeability of the magnet material.
Reluctance of magnetic material.
