“Protective discrimination” means the progressive grading of sizes or tripping times of:
Line fuses and overcurrent relays.
Magnetic and thermal current transformers.
440 V and 220 V transformers.
The figures show a graphical symbol for a particular electronic component and a typical working characteristic for the same component. Which component?
Silicon controlled rectifier (SCR).
Ordinary thyristors (SCR) must often be protected against reverse overvoltage transients. This is because they can be damaged by over-voltage, even if it is of extremely short duration. These SCRs have been given such over-voltage protection, but only one of them is correct. Which one is it?
Diodes are widely used in rectification, or the conversion of alternating current to direct current. The sinusoidal input voltage V(in) is applied to the circuit shown. Which of the output voltages is correct?
What could the wheelman be asked to do, to help in the preparations to leave the berth and go to sea?
Test the steering by putting the wheel hard over both ways.
Help the after team let go the ropes.
Standby in the mess room until called to the bridge.
Help the forward team let go the ropes.
This circuit consists of a voltage source V, a change-over switch S, a resistor R and a capacitor C. The voltage/time figures 1 to 4 show changes in the voltage V(C) when the switch S is suddenly shifted from position 1 to 2 at time t = 0. Only one of the diagrams is correct. Which?
This circuit consists of a current source I, a change-over switch S, a resistor R and a capacitor C. The current/time figures 1 to 4 show possible changes in the current I when the switch S is suddenly shifted from position 1 to 2 at time t = 0. Which diagram is correct?
Where is the “FORECASTLE” in the figure?
The Forecastle is indicated by B.
The Forecastle is indicated by C.
The Forecastle is indicated by A.
The Forecastle is indicated by D.
This circuit shows a transformer with two windings, N (1) = 2 000 and N (2) = 1 000 turns, on a common magnetic circuit. Assume that there are no energy losses in the transformer itself. Calculate the output voltage V (2) when the input voltage is V (1) = 100 Volt.
Which cell voltage is required to trickle charge a lead acid battery?
During an anchoring operation, what does the bridge team mean when they ask “How is the chain leading”?
The bridge would like to know the direction of the anchor cable from the hawse pipe.
The Master is asking the Chief Officer whether the ship needs to be moved forward and take the weight off the anchor cable.
The Master is asking the Chief Officer whether the vessel is dragging anchor.
What do you call the wide rung on a pilot ladder that prevents the ladder from twisting?
The wide rung on a pilot ladder that prevents it from twisting is called a “Spreader”.
The wide rung on a pilot ladder that prevents it from twisting is called a “Wide step”
The wide rung on a pilot ladder that prevents it from twisting is called a “Long rung”
The wide rung on a pilot ladder that prevents it from twisting is called a “Ani-twist rung”
On the diagram, what is the area at the forward end of the vessel shown by the letter “A”? It is normally raised by one deck above the main deck.
Where is the “PORT QUARTER”, in the figure?
The Port quarter is D in the figure.
The Port quarter is A in the figure.
The Port quarter is B in the figure.
The Port quarter is A in the figure.
Which is the “CAPSTAN” in the figure?
The Capstan is indicated by A in the figure.
The Capstan is indicated by B in the figure.
The Capstan is indicated by C in the figure.
The Capstan is indicated by D in the figure.
The pressure inlet to a pressure gauge is varied from zero to full scale and back to zero again. The output (indicating pressure) versus true pressure is shown in the diagram.The non-coincidence (mismatch) of loading and unloading curve is due to internal friction in the instrument. What do we call this phenomenon?
In a PID controller it is possible to change the setting of the Proportional band (P), the Reset time (I) and the Rate time (D). Please indicate which curve shows the typical response to a step change in input, if the setting of the reset time is too small.
What is name of the machine shown, used to heave on the ropes during mooring and unmooring?
In fresh water tank we are using a pressure transmitter with a range of 0-0,5 bar/4-20 mA for level measurement. The transmitter is installed 30 centimetres from the bottom of the tank, and the tank is 5 meters high. What will the output from the transmitter be when the tank is empty?
Can a ZENER BARRIER be installed in a hazardous area?
No, as only the output from the barrier is intrinsically safe this is not allowed.
Yes, that’s what the zener barrier is made for.
Only if properly marked for such installation.
Only in equipment operating on very low voltage.
The inductance which will induce an EMF of 1 Volt in a conductor when the current is changing at a rate of 1 Amp per second, is defined as:
Which of the following methods may a diode may be tested by?
Use a Digital Multi-Meter set to check forward voltage and reverse current blocking.
Connect to low ohms resistance tester.
Use an insulation resistance tester (Megger).
Use a Digital Multi-Meter set to measure ohms in forward and reverse directions.
When starting three phase induction motors which of the following starting methods will immediately apply rated voltage to the machine?
The picture shows the component parts of a fluorescent light (items 10 to 14) above a circuit diagram (items 1 to 9). Between which terminals of the circuit should the ballast (or choke) be connected?
A cable has a resistance of 100 milli-ohms. It supplies a 300 A load over a distance of 100 metres. What is the voltage drop along it’s length?
In a closed loop control system the error signal is derived from which of the following?
The demand and the feedback signal.
The process and the demand.
The process and the feedback sensor.
The tolerance of the feedback sensor.
A thermistor which provides feedback for a thermal control system is suspected to have failed. Assuming there is no available direct/identical replacement for thermistor, which of the following methods may be used to prove it has failed?
Disconnect the thermistor lead from the controller and replace with a mV source.
Disconnect the thermocouple lead from the controller and replace with a mA source.
Connect a mA source in parallel with the thermocouple connections.
Connect a mV source in parallel with the thermocouple connections.
A galley hot plate uses a Nichrome / Magnesium Oxide heating element and is to be tested before being put into service for the first time. An insulation resistance test yields a reading of 0,3 M Ohm. Which action should be taken?
Apply reduced voltage to the element for a few minutes. Then retest and if ok put into service.
Wash the element in a degreasing agent. Then retest and if ok put it into service.
Put the element into service.
A High Breaking Capacity fuse found in a Main High Voltage Switchboard will typically have fault level rating of?
When there is a need to interrupt current flow in a high voltage system it may be very difficult to quench the electrical arc which is generated at the circuit breaker contacts. Which of the following arcing media is commonly found in high voltage marine switchgear?
Three earth lamps indicate (under no test mode) – bright – bright – dark. Which of the following is indicated by this condition?
No faults on the system but a failed lamp.
Two phases have a partial fault to earth and one is good.
Two phases are good and one has a hard fault to earth.
Two phases are good and one has a partial fault to earth.
Continuity testing of a delta connected three phase induction motor yields the following results; U – V = 3 ohms, V – W = 3 ohms, W – U = 6 ohms. Which of the following is the likely condition?
Open circuit winding between W and U.
Short circuit winding between W and U.
Short circuit between V and Earth.
Partial fault between W and U.
The continuity resistance of a 100 m long × 25 sq. mm cable (rated at 100 A) is to be checked. Which of the following results would you anticipate?
Between 0,1 and 1,0 Micro Ohm.
Between 0,1 and 1,0 M Ohm.
A 250 V contactor has been fitted to a 220 V supply. Which of the following symptoms might be observed?
Contactor chattering (vibrating).
Which of the following is the minimum acceptable value of insulation resistance for High Voltage equipment?
When selecting switchgear to work with High Voltage it is important to use an appropriate arc quenching medium. What is meant by arc quenching medium?
The gas, liquid or vapour which will minimise creation of an electric arc as contacts open.
A material which assists a welding process.
Equipment which communicates information about the arcing.
The way in which the contacts separate as the switchgear operates.
High Voltage systems rely on the installed protective equipment being able to interrupt any fault in the system. Throughout the system, the fault level has been calculated, and under no circumstances must the system be modified to exceed this fault level. What is meant by fault level?
The amount of apparent power that could flow into any fault at any point in the electrical network.
The current level flowing into a symmetrical short circuit fault between all three phases.
The current level flowing into a dead short to earth at any point on the ship, directly from the High Voltage System.
What type of Ex equipment is suitable for installation in Zone 0 hazardous area?
When we are measuring salinity with a salinometer, the type of sensing device is:
In an automatic temperature control system, operating with a PID controller which of the following settings or parameter adjustments may result in system oscillation?
What are the main elements for Process Control?
Process, Sensor, Final control element and Controller.
Sensor, Modulation, Controller, Process.
Sensor, Controller, Noise, Final Control Element.
Resistor, Capacitor, Battery, Load.
Following shows circuitry of a peak detector. What is the output voltage curve, Vo if Vi is a sinusoidal input curve?
Vo will be the same sinusoidal curve but at a lesser amplitude.
Vo will peak when Vi is at the maximum, remain constant and fall to zero when Vi becomes negative.
Vo will spike when Vi is at the maximum/minimum point of the sinusoidal curve; zero everywhere else.
Vo will peak at a level less than Vi maximum voltage and remain constant throughout.
When selecting switchgear to work with High Voltage it is important to use an appropriate arc quenching medium. What is meant by arc quenching medium?
The gas, liquid or vapour which will minimise creation of an electric arc as contacts open.
Equipment which communicates information about the arcing.
The way in which the contacts separate as the switchgear operates.
A material which assists a welding process.
A 250 V contactor has been fitted to a 220 V supply. Which of the following symptoms might be observed?
Contactor chattering (vibrating).
This circuit consists of a current source I, a change-over switch S, a resistor R and a capacitor C. The current/time figures 1 to 4 show possible changes in the current I when the switch S is suddenly shifted from position 1 to 2 at time t = 0. Which diagram is correct?
Which cell voltage is required to trickle charge a lead acid battery?
An important quantity which is useful in circuit analysis is known as conductance G (Siemens). Which of the formulas express the conductance for this circuit?
A 5 V DC source has an internal impedance of 0,2 ohms. When a load of 2,3 ohms is applied what voltage will be measured at the source terminals?
What principle of measurement are viscosity controllers usually based upon?
Measurement of two different temperatures.
Measurement of temperature.
Measurement of differential pressure.
What is the maximum current that a 15 V, 3 Watt Zener diode can handle without damage?
The inductance, which will induce an EMF of 1 Volt in a conductor, when the current is changing at a rate of 1 Amp per second, is defined as:
The typical current gain for a common emitter transistor is:
The instrument most widely used for testing of semiconductor diodes is:
A 6-Volt DC relay is to be used with a 12-Volt power supply. The relay requires a current of 0,1 Amp. What is the series resistance required?
In the diagram, which letter is pointing to the area of the ship known as the “STERN”?
The Stern area is indicated by C.
The Stern area is indicated by B.
The Stern area is indicated by A.
The Stern area is indicated by D.
Some ships generate electrical power at 440 V, but then step up this voltage to supply specific electrical equipment. One common example, may be to feed a large bow thruster. Why is this done?
The overall ship’s electrical load does not justify a High Voltage generating plant. This method allows more power to be delivered to the bow thruster at low running cost.
Manufacturers can supply High Voltage bow thrusters at less cost, and the power factor is improved.
A large bow thruster will draw very large currents at low voltage. Being typically remote from the generator, significant voltage drops would occur at low voltage.
The shipyard could not purchase a High Voltage generating plant at the time of manufacture, so they used what was available at the time.
When work must be done on High Voltage equipment, it is vital that the equipment is earthed (grounded) after isolation procedures have been carried out. Why is this?
To provide a reference point, and so ensure accuracy of any test results.
To ensure that it is dead, even if there was a flaw in the isolation procedure.
To ensure that no energy remains in the system, and that it cannot be recharged by external influences.
To ensure that the equipment does not overheat due to currents circulating through earth (ground).
When selecting switchgear to work with High Voltage it is important to use an appropriate arcing medium. What is meant by arcing medium?
The gas, liquid or vapor, which will minimize creation of an electric arc as contacts open.
Equipment, which communicates information about the arcing.
A material, which assists a welding process.
Sometimes an early warning of failure in High Voltage switchboards may be an unpleasant smell. If the switchboard uses gas circuit breakers, which of the following may indicate a potential problem?
Why could dirty and oily areas of the deck be dangerous?
They may cause people to slip over and hurt themselves.
They show the ship is not efficient.
They are areas which should be cleaned up.
They do not look good to the customers.
What do you understand by “Bitter end”?
Bitter end means: the end link of an anchor cable that is secured within the chain locker.
Bitter end means: a foul taste at the end of a meal.
Bitter end means: the toggled end of a lifeboat painter.
Bitter end means: to the very last moment.
In the diagram, which letter is indicating the position “MIDSHIPS”?
Midships is indicated by B in the figure.
Midships is indicated by D in the figure.
Midships is indicated by C in the figure.
Midships is indicated by A in the figure.
When keeping a lookout, what would be the correct understanding of the question “What is the aspect of the other ship”?
The question is requesting some indication of what lights or part of the vessel is seen.
The question is requesting where on the horizon the other ship was sighted.
The question wants to know what type of ship has been sighted.
The question is requesting some idea of how far away the other ship is from your own ship.
What is understood by the term “take the helm”?
Take over the steering of the ship.
Take over heaving of a rope.
Change the place where the lookout is standing.
Take a message to another officer.
Would there ever be the need for two lookouts on the Bridge watch?
Yes, possibly whne there is dense fog and heavy traffic.
Every night there should be two lookouts, one on each bridge wing.
No, one lookout is sufficient even in fog.
If the order is given to a mooring deck to “make fast”, what would happen?
Make fast means to apply a lashing to a coiled mooring rope.
Mooring ropes are transferred from a winch drum to the bitts.
Make fast means to set very quickly.
Mooring ropes are transferred from a storage drum to a winch to start heaving.
What is a ship’s “Gangway”?
A Gangway is a portable means of access between the ship and the shore.
A Gangway is an interval of time between a change of working gangs, on board.
A Gangway is the means of access into the cargo holds.
What is meant by the term “bunkers”?
It means the number of available bunk spaces available on the vessel.
It means fuel oil used in the ship’s engine(s).
It refers to the storing of lubricating oil.
It is a measure of the quantity of oil; cargo loaded.