mrk nthny
Quiz by , created more than 1 year ago

competency Quiz on c05a, created by mrk nthny on 14/08/2016.

447
1
0
mrk nthny
Created by mrk nthny over 8 years ago
Close

c05a

Question 1 of 131

1

What is the maximum allowable primary current of a 2 KVA step - down transformer with a four to one turns ratio if connected across a 440 volt line?

Select one of the following:

  • 4.5 amps

  • 1.1 amps

  • 18.1 amps

  • 27.7 amps

Explanation

Question 2 of 131

1

The open-circuit voltage of a fully charged lead-acid battery cell is _______ .

Select one of the following:

  • 2.0 volts

  • 2.3 volts

  • 1.5 volts

  • 1.8 volts

Explanation

Question 3 of 131

1

A milliammeter, with a full scale deflection reading of 100 milliamps, is known to have an accuracy of + or - 2%. A meter reading of 10 milliamps would indicate a line current of between.

Select one of the following:

  • 9.8 and 10.2 milliamperes

  • 8.0 and 12.0 milliamperes

  • 9.8 and 10.0 milliamperes

  • 8.0 and 10.0 milliamperes

Explanation

Question 4 of 131

1

Basic electrical motor action depends on_______.

Select one of the following:

  • a current carrying conductor placed in a magnetic field

  • a conductor rotated within a magnetic field

  • the relative force of the commutator and commutating poles

  • the relative force of the armature and interpoles

Explanation

Question 5 of 131

1

What is the function of damper windings in a synchronous motor ?

Select one of the following:

  • DC voltage to the field

  • AC voltage to the armature

  • AC voltage to the field

  • DC voltage to the armature

Explanation

Question 6 of 131

1

The Wheatstone bridge is a precision measuring instrument utilizing the principle of changes in____ .

Select one of the following:

  • resistance

  • amperage

  • inductance

  • capacitance

Explanation

Question 7 of 131

1

"The rated temperature rise of an electric motor is the_______.
.
"

Select one of the following:

  • normal temperature rise above the standard ambient temperature at rated load

  • average temperature at any given latitude

  • average temperature rise due to resistance at 10% overload

  • permissible difference in the ambient temperature of the motor due to existing weather conditions

Explanation

Question 8 of 131

1

The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the______.

Select one of the following:

  • main switchboard

  • bridge control panel

  • disconnect links

  • governor relay box

Explanation

Question 9 of 131

1

Voltage generated by most AC generators is fed from the machine to the bus by means of ____ .

Select one of the following:

  • direct connections from the stator

  • brushes on slip rings

  • brushes on a commutator

  • slip rings on a commutator

Explanation

Question 10 of 131

1

Battery charging rooms should be well ventilated because the charging process produces ______.

Select one of the following:

  • explosive gases

  • corrosive gases

  • highly poisonous gas

  • highly combustible oxygen

Explanation

Question 11 of 131

1

Battery charging rooms should be well ventilated because the charging process produces ______.

Select one of the following:

  • explosive gases

  • corrosive gases

  • highly poisonous gas

  • highly combustible oxygen

Explanation

Question 12 of 131

1

When reading electrical motor controller diagrams, it helps to know that________.

Select one of the following:

  • current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines

  • current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines

  • circuits subject to 500 volts or greater are drawn as heavy lines and below 500 volts as lighter lines

  • circuits subject to 500 volts or greater are drawn as light lines and below 500 volts as heavy lines

Explanation

Question 13 of 131

1

A device that utilizes the principle of electromagnetic induction is the______ .

Select one of the following:

  • transformer

  • diode

  • transistor

  • rheostat

Explanation

Question 14 of 131

1

Amortisseur windings are installed in a synchronous motor to_____.

Select one of the following:

  • provide a means for starting

  • eliminate arcing between the stator and the rotor

  • produce a higher power factor

  • reduce eddy current losses

Explanation

Question 15 of 131

1

Which of the following physical characteristics does a wound- rotor induction motor possess that a squirrel cage motor has none?

Select one of the following:

  • Slip rings

  • End rings

  • A centrifugal switch

  • End plates

Explanation

Question 16 of 131

1

In an induction motor, rotor currents are circulated in the rotor by________.

Select one of the following:

  • inductive reaction of the rotating stator field

  • external variable resistors

  • slip rings and brushes

  • an armature and brushes

Explanation

Question 17 of 131

1

Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in armature reaction are compensated by the ________.

Select one of the following:

  • voltage regulator

  • governor speed droop setting

  • balance coil

  • phase-balance relay

Explanation

Question 18 of 131

1

"A low voltage source is being used for testing armature coils. A
coil short circuit will be indicated by a ___________.
"

Select one of the following:

  • low or zero voltage reading, while the other coils will have higher readings

  • high voltage reading, while the other coil readings will have an equal or lower value

  • fluctuating voltmeter reading, while the other coil readings are steady

  • steady voltmeter reading, while the other coil readings are fluctuating

Explanation

Question 19 of 131

1

When measuring AC current flow, you must always connect the meter ___________.

Select one of the following:

  • in series with the power source and load

  • in parallel with the power source and load

  • insuring correct polarity

  • using the lowest range possible to prevent instrument damage

Explanation

Question 20 of 131

1

To increase the frequency of an operating AC generator, you should __________.

Select one of the following:

  • increase the speed of the prime mover

  • increase the field excitation

  • decrease the field excitation

  • increase the number of magnetic poles

Explanation

Question 21 of 131

1

An electrical device which prevents action from occurring until all other required conditions are met is called _______.

Select one of the following:

  • interlock

  • limit

  • monitor

  • modulator

Explanation

Question 22 of 131

1

The main purpose of the auxiliary winding on a split-phase, single- phase motor is to_______ .

Select one of the following:

  • start the motor

  • limit the starting voltage

  • increase the starting current

  • keep the motor running in the event the main winding should fail

Explanation

Question 23 of 131

1

The heating of conductors as a result of resistance in a distribution circuit causes a power loss expressed as_______.

Select one of the following:

  • line loss

  • line droop

  • IR drop

  • hysteresis

Explanation

Question 24 of 131

1

The greatest detrimental effect on idle electrical equipment, such as cargo pump motor is the_______.

Select one of the following:

  • absorption of moisture in the insulation

  • loss of residual magnetism

  • insulation varnish flaking

  • dirt collecting on the windings

Explanation

Question 25 of 131

1

"An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a_______.
.
"

Select one of the following:

  • ship's service alternator

  • magnetic amplifier

  • three-wire DC generator

  • saturable core reactor

Explanation

Question 26 of 131

1

"A circuit breaker differs from a fuse, in that a circuit breaker_________.
.
"

Select one of the following:

  • trips to break the circuit and may be reset

  • melts and must be replaced

  • is enclosed in a tube of insulating material with metal ferrules at each end

  • gives no visual indication of having opened the circuit

Explanation

Question 27 of 131

1

AC circuits possess characteristics of resistance, inductance, and capacitance. The capacitive reactance of a circuit is expressed in_____ .

Select one of the following:

  • ohms

  • mhos

  • henrys

  • farads

Explanation

Question 28 of 131

1

The frequency output of an operating alternator is controlled by the______ . .

Select one of the following:

  • relative speed of the rotor poles

  • number of turns of wire in the armature coil

  • strength of the magnets used

  • output voltage

Explanation

Question 29 of 131

1

Which of the following types of motors is often designed for use in correcting power factor?

Select one of the following:

  • Synchronous

  • Polyphase

  • Wound-rotor

  • Induction

Explanation

Question 30 of 131

1

The purpose of a cage rotor winding placed on the rotor of a synchronous motor is to ________.

Select one of the following:

  • start the machine as an induction motor

  • provide excitation to the DC field

  • contribute extra torque at synchronous speed

  • prevent the machine from falling out of step

Explanation

Question 31 of 131

1

A constant output voltage from an AC generator is maintained by the_________.

Select one of the following:

  • voltage regulator

  • reverse power relay

  • exciter generator

  • prime mover governor

Explanation

Question 32 of 131

1

The capacity of a storage battery is measured in_______.

Select one of the following:

  • ampere-hours

  • volts

  • farads

  • amps

Explanation

Question 33 of 131

1

The rated temperature and rise of an electric motor is the ______.

Select one of the following:

  • normal temperature rise above the standard ambient temperature at rated load

  • average temperature at any given latitude

  • average temperature rise due to resistance at 10% overload

Explanation

Question 34 of 131

1

"In an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in armature reaction are compensated by the_______ .
.
"

Select one of the following:

  • voltage regulator

  • governor speed droop setting

  • balance coil

Explanation

Question 35 of 131

1

What should you do to the charging current when a lead-acid battery gassing freely while receiving a normal charge?

Select one of the following:

  • Reduce

  • Increase

  • Stop

  • No adjustment needed

Explanation

Question 36 of 131

1

External shunts are sometimes used with ammeters to _____.

Select one of the following:

  • prevent damage to the meter movement from heat generated by the internal shunt

  • increase meter sensitivity

  • permit shunts with larger resistance to be utilized

  • reduce reactive power factor error

Explanation

Question 37 of 131

1

What is a common method used to control the speed of the AC propulsion motor on a diesel-electric propulsion ship?

Select one of the following:

  • Change the input frequency of the voltage to the motor

  • Increase the motor voltage

  • Decrease the motor voltage

Explanation

Question 38 of 131

1

What keep the line losses in a distribution circuit at minimum?

Select one of the following:

  • Use higher voltage and lower current

  • Increase the number of thermal relays in the circuit

  • Use higher current and lower voltage

  • Add rubber insulation conductors to the circuit

Explanation

Question 39 of 131

1

The Wheatstone bridge is a precision measuring instrument utilizing the principle of changes in ____.

Select one of the following:

  • resistance

  • inductance

  • capacitance

  • amperage

Explanation

Question 40 of 131

1

In a compound-wound motor, where is a portion of the line current flows through?

Select one of the following:

  • Shunt field coils

  • Inertia poles

  • Stator

  • Frame

Explanation

Question 41 of 131

1

How does the speed of a synchronous motor change?

Select one of the following:

  • Changing the input frequency

  • Interchanging any tow of the three live leads

  • Changing the voltage of the system

  • Increasing the field excitation

Explanation

Question 42 of 131

1

Which of the following is the function of an automatic voltage regulators provided on main switchboards?

Select one of the following:

  • It varies field excitation to the generators

  • It governs prime mover speed to control voltage

  • Protect the switchboard from high voltage

  • Regulate the AC load on the generator

Explanation

Question 43 of 131

1

What will happen if you reverse the DC current flow through an electrical coil?

Select one of the following:

  • Its two-pole field will reverse

  • It will reduce the amount of flux produced

  • It will change its impedance

  • It will reduce the power consumed

Explanation

Question 44 of 131

1

Power transformers are rated in _____.

Select one of the following:

  • kilovoltamperes

  • kilowatt-amps

  • ampere-turns

  • kilowatt-volts

Explanation

Question 45 of 131

1

When the voltage and the current developed in an AC circuit reach their peak values at the same time, the power factor is considered to be _____.

Select one of the following:

  • unity

  • lagging

  • leading

  • infinity

Explanation

Question 46 of 131

1

When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is ___.

Select one of the following:

  • maximum

  • lagging

  • leading

  • minimum

Explanation

Question 47 of 131

1

The operating torque of the disk or timer element in an AC reverse power relay is obtained from _____.

Select one of the following:

  • electromagnets

  • line voltage

  • a separate battery source

  • the main bus

Explanation

Question 48 of 131

1

One important difference between wye-connected and delta-connected generators is that delta connections have ____.

Select one of the following:

  • line voltage equal to the phase voltage

  • line voltages equal to the vector sum of the phase voltages

  • phase voltage 90º out of sync

  • line current equal to the phase current

Explanation

Question 49 of 131

1

The load sharing characteristics of two diesel alternators operating in parallel are directly related to the setting of their governors’_____.

Select one of the following:

  • speed droop

  • Load limit

  • idle speed

  • speed limit

Explanation

Question 50 of 131

1

Why is the engine room watch officers should keep a constant check on the loads carried by electric motors?

Select one of the following:

  • Exceeding nameplate value shortens useful life

  • Low loads necessitate frequent insulation cleaning

  • Residual magnetism may increase

  • Energy is wasted if full loading is not utilized

Explanation

Question 51 of 131

1

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot winding and sparking at the brushed?

Select one of the following:

  • Reversed interpole polarity

  • Low series field current

  • High shunt field current

  • Excessive humidity

Explanation

Question 52 of 131

1

Which of the following starting system should be carried out after overhaul of a motor?

Select one of the following:

  • No load

  • Low speed

  • High speed

  • Medium speed

Explanation

Question 53 of 131

1

What is the common source of field excitation for synchronous motors?

Select one of the following:

  • DC rectifier

  • Low voltage battery

  • Motor attenuator set

  • AC supply

Explanation

Question 54 of 131

1

What is a component used to protect the DC generator circuits against malfunctions due to prime mover power loss?

Select one of the following:

  • Reverse current relays

  • Main bus disconnect links

  • A separate battery back-up

  • Reverse power relays

Explanation

Question 55 of 131

1

Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in _______.

Select one of the following:

  • motor starting circuit

  • main lighting circuits

  • emergency lighting circuits

  • general alarm circuits

Explanation

Question 56 of 131

1

Equalization of the power factors of two alternators operating in parallel is accomplishedin what manner?

Select one of the following:

  • Accomplish automatically by the automatic voltage regulator

  • Manually adjusting the governor controls

  • Manually adjusting the output of current transformers

  • Accomplish automatically by the designed action of the governors

Explanation

Question 57 of 131

1

Which of the following electrical instrument is the safest to use in taking the current even without switching off or opening the circuit?

Select one of the following:

  • Clamp meter

  • Meager tester

  • Ammeter

  • Multi tester

Explanation

Question 58 of 131

1

Relative to the secondary winding of a step-up transformer, the primary winding will have ____.

Select one of the following:

  • fewer turns

  • more turns

  • same number of turns but smaller wires

  • twice as many turns

Explanation

Question 59 of 131

1

What will happen if connections on a DC shunt motor are changed on either the field connections, or the armature connections?

Select one of the following:

  • Direction of rotation will be reversed

  • Motor will not run

  • Direction of rotation will be the same

  • Motor will run as a generator

Explanation

Question 60 of 131

1

What is the purpose of DC generator brushes?

Select one of the following:

  • Conduct electric current to an outside current

  • Neutralize armature reaction

  • Convert DC current to AC current

  • Provide excitation to a DC generator

Explanation

Question 61 of 131

1

A switchboard for an AC electrical system requires the use of which of the following devices?

Select one of the following:

  • Frequency meter

  • Ohmmeter

  • Induction voltage regulator

  • Current transformer governor

Explanation

Question 62 of 131

1

A bus disconnect link is used to isolate ___.

Select one of the following:

  • the generator circuit breaker from the bus

  • one bus bar from the ground detection system

  • different bus phases form the equalizer connection

  • positive and negative buses from the neutral

Explanation

Question 63 of 131

1

The purpose of a magnetic relay is to ______.

Select one of the following:

  • remotely open and close contacts

  • open a circuit only in the event of overload

  • provide overcurrent protection during starting

  • relay voltages at increased power

Explanation

Question 64 of 131

1

As storage battery for an emergency lighting and power system must have the capacity to ____.

Select one of the following:

  • close all watertight doors twice

  • open all watertight doors four time.

  • open and close all watertight doors in six consecutive cycles within a 20 second period

  • none of the above

Explanation

Question 65 of 131

1

On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive over travel of the actuating valve by the control motor. What are these devices?

Select one of the following:

  • Limit switches

  • Overlap sensors

  • Differential relays

  • Analog relays

Explanation

Question 66 of 131

1

The shunt of a DC ammeter should be connected in _____.

Select one of the following:

  • series with the load and in parallel with the meter movement

  • parallel with the load in series with the meter movement

  • parallel with the load and in parallel with the meter movement

  • series with the load and in series with the meter movement

Explanation

Question 67 of 131

1

When a transformer is used to step-down voltage, the low voltage winding is ___.

Select one of the following:

  • the secondary coil

  • part of the core

  • the primary coil

  • not insulated

Explanation

Question 68 of 131

1

What inidicates a violent gassing developed by a lead-acid battery during charging?

Select one of the following:

  • Charging rate is excessive

  • Plate separators are grounded

  • Cell voltages are excessive

  • Specific gravity is insufficient

Explanation

Question 69 of 131

1

When the non-essential load has been removed from the feeder system but the service generator remains overloaded, what device automatically activates?

Select one of the following:

  • Overcurrent tripping device

  • Preferential tripping system

  • Time delay trip device

  • ACB trip device

Explanation

Question 70 of 131

1

What is the function of capacitors which are commonly used on power supply circuits for engine room automation consoles?

Select one of the following:

  • To filter out ripple for rectification

  • prevent overloads

  • act as a permanent load

  • decrease the average value of the output voltage

Explanation

Question 71 of 131

1

What do you call the device where a low input voltage is imparted to it which then delivers a high output voltage?

Select one of the following:

  • Step-up transformer

  • Primary transformer

  • Secondary transformer

  • Step-down transformer

Explanation

Question 72 of 131

1

What electrical component intitiates the division of the reactive KVA load between paralleled AC generators?

Select one of the following:

  • Voltage regulators

  • Prime mover governors

  • Proportioner

  • Phase balance relay

Explanation

Question 73 of 131

1

The circuit power factor of an AC generator operating singularly is determined by the ____.

Select one of the following:

  • connected load

  • prime mover speed

  • ground current

  • generator’s rated voltage

Explanation

Question 74 of 131

1

What do you call a torque produced by a motor when the shaft will not turn, even though rated voltage is applied to the stator?

Select one of the following:

  • Locked rotor torque

  • Pullout torques

  • Breakdown torque

  • Torque margin

Explanation

Question 75 of 131

1

What will happen if you reverse the DC current flow through an electrical coil?

Select one of the following:

  • Reverse its two-pole field

  • Reduce the power consumed

  • Change its impedance

  • Reduce the amount of flux produced

Explanation

Question 76 of 131

1

Which of the following provides the initial torque to turn a DC generator?

Select one of the following:

  • A mechanical prime mover

  • Residual magnetism in the armature

  • Residual magnetism in the field poles

  • Residual magnetism in voltage regulator

Explanation

Question 77 of 131

1

The division of kilowatt load between two AC generators operating in parallel is controlled by the settings and characteristics of the ____.

Select one of the following:

  • prime mover governors

  • reverse power relays

  • field rheostat

  • voltage regulators

Explanation

Question 78 of 131

1

On some diesel-electric ships, the DC propulsion motor will only attain half speed when the generator fields are fully excited. How should the speed above this be obtained?

Select one of the following:

  • Raise the generator engine speed

  • Rotate brush alignment

  • Decrease excitation

  • Lower the generator engine speed

Explanation

Question 79 of 131

1

What do you call a DC generator used to supply direct current in order to maintain an AC generator field?

Select one of the following:

  • Exciter

  • Rotor

  • Stator

  • Armature

Explanation

Question 80 of 131

1

Transformer cores are laminated to reduce ____.

Select one of the following:

  • eddy currents

  • secondary flux

  • leakage flux

  • tertiary flux

Explanation

Question 81 of 131

1

To test the feeder system for grounding, the three earth lamps will be activated when this switch is manipulated.

Select one of the following:

  • The push button switch

  • Selector switch

  • Micro switch

  • Lamp switch

Explanation

Question 82 of 131

1

A transformer works on the basic principle of ____.

Select one of the following:

  • mutual induction

  • self impedance

  • attraction and repulsion

  • increasing power

Explanation

Question 83 of 131

1

What is the simplest method of controlling the terminal voltage of compound-wound DC generator?

Select one of the following:

  • With a hand-operated field rheostat connected in series with line shunt field circuit

  • Separate exciter in a series with the shunt field

  • Carbon pile regulator in series with load

  • Balance coil diverting neutral current through the shunt field

Explanation

Question 84 of 131

1

Which of the following types of motor has two separate field windings usually connected in parallel with the armature circuit?

Select one of the following:

  • Compound-wound motor

  • Series-wound motor

  • Shunt-wound motor

  • Induction motor

Explanation

Question 85 of 131

1

Which of the following types of motor whose speed at normal operation is constant or practically constant?

Select one of the following:

  • Universal motor

  • Series-wound motor

  • Synchronous speed motor

  • Regulated speed motor

Explanation

Question 86 of 131

1

A circuit with a blown fuse would be described as ____ _____

Select one of the following:

  • open circuit

  • short circuit

  • bonded circuit

  • grounded circuit

Explanation

Question 87 of 131

1

How would you describe a circuit with a blown fuse?

Select one of the following:

  • Open circuit

  • Short circuit

  • Bonded circuit

  • Grounded circuit

Explanation

Question 88 of 131

1

Which of the following operating characteristics for DC motors is considered to give high starting torque?

Select one of the following:

  • Series

  • Shunt

  • Cumulative-compound

  • Differential-compound

Explanation

Question 89 of 131

1

The resistance value of a resistor in a circuit can best be determined by the ______.

Select one of the following:

  • band markings on the resistor

  • single solid body color of the resistor

  • amperage value written on the resistor

  • physical size of the resistor

Explanation

Question 90 of 131

1

What is the recommended practice on the frequency of the incoming machine prior to closing the breaker when paralleling two AC generators?

Select one of the following:

  • Slightly greater than the line frequency

  • Slightly less than the line frequency

  • The same as the line frequency

  • Greater than the line frequency

Explanation

Question 91 of 131

1

When two AC generators are being paralleled, the breaker should be closed with the synchroscope pointer rotating in what direction?

Select one of the following:

  • FAST direction, just before the 12 o’clock position

  • SLOW direction, just before the 12 o’clock position

  • FAST direction, just after the 12 o’clock position

  • SLOW direction, just after the 12 o’clock position

Explanation

Question 92 of 131

1

What is the characteristic of the mica used in the commutators of DC machinery?

Select one of the following:

  • Harder than copper

  • Softer than copper

  • Same hardness as copper

  • Softer than copper but wears away at slower rate

Explanation

Question 93 of 131

1

Regarding an induction motor, where is the output power developed related to?

Select one of the following:

  • Slip of the rotor

  • Speed of the rotating field

  • DC filed excitation

  • Current flow in the interpoles

Explanation

Question 94 of 131

1

What type of AC single-phase motor will also operate on direct current?

Select one of the following:

  • Series-wound

  • split-phase

  • Shaded-pole

  • Repulsion-start

Explanation

Question 95 of 131

1

What do you call an AC motor which uses rheostat in the motor circuit to vary the speed?

Select one of the following:

  • Wound rotor induction motor

  • Squirrel cage induction motor

  • Regenerative braking motor

  • Squirrel-cage induction motor

Explanation

Question 96 of 131

1

Which of the following is the most common of excitation for synchronous motor?

Select one of the following:

  • DC supply

  • Step-up transformer

  • AC supply

  • Poor contact of brushes

Explanation

Question 97 of 131

1

Which of the listed transformers uses a single winding to produce voltage transformation?

Select one of the following:

  • Autotransformers

  • Step up transformers

  • Stepdown transformers

  • Isolation transformers

Explanation

Question 98 of 131

1

What type of electric motor is commonly used to start small auxiliary diesel engines?

Select one of the following:

  • Series

  • Synchronous

  • Cage

  • Shunt

Explanation

Question 99 of 131

1

Which of the following electric motors would be the most reliable to use on the open main deck of a vessel?

Select one of the following:

  • Watertight motors

  • Synchronous motors

  • Drip proof motors

  • Squirrel cage motors

Explanation

Question 100 of 131

1

When a megohmmeter is used to test the dielectric strength of wire insulation, what causes the intial dip of the pointer toward zero?

Select one of the following:

  • The capacitance of the circuit

  • The dielectric absorption effect of the insulation

  • The leakage of current along the surface of dirty insulation

  • Good insulation

Explanation

Question 101 of 131

1

On a modern 13 amp square pin electric plugs, which of the following statements is true ?

Select one of the following:

  • The fuse is at the neutral connection.

  • The neutral wire is coloured brown.

  • The live wire is coloured blue.

  • The earth wire goes to the centre top connection.

Explanation

Question 102 of 131

1

The timer element of a reverse power relay will activate when ___

Select one of the following:

  • the power flow is the same as the tripping direction

  • the power flow is the opposite to the tripping direction

  • the movement if the disk is damped by a permanent magnet

  • the load difference generators is more than 10 percent

Explanation

Question 103 of 131

1

The difference between the synchronous speed of a three phase induction motor and its operating speed is called slip and may be correctly expressed as_______.

Select one of the following:

  • a percent of synchronous speed

  • the reduced amp rating

  • the decrease in shaft torque

  • reduced fuel consumption

Explanation

Question 104 of 131

1

What determines the cycle per second developed by the alternator aboard your vessel?

Select one of the following:

  • The speed of the engine driving the alternator

  • The resistance applied to the field rheostat

  • The synchronous speed of induction

  • The adjustment made to the voltage regulator

Explanation

Question 105 of 131

1

Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 step down transformer?

Select one of the following:

  • The secondary windings have half as many turns as the primary windings

  • The secondary windings have twice as much resistance as the primary windings

  • The secondary windings use smaller wires than the primary windings

  • The secondary windings can only provide half as much current as the primary windings

Explanation

Question 106 of 131

1

What will happen if there is a change in field excitation of an alternator operating in parallel?

Select one of the following:

  • There will be a change in voltage output

  • There will be change in alternator frequency

  • There will be a change in kilowatt load

  • There will be a change in current rating

Explanation

Question 107 of 131

1

What is the advantage of DC motors over AC motors?

Select one of the following:

  • Offer infinite speed variations

  • They are less expensive

  • They require less maintenance

  • They offer slow speed

Explanation

Question 108 of 131

1

A galvanometer is an instrument used to measure ____.

Select one of the following:

  • very small amounts of current or voltage

  • thickness of galvanized metal

  • resistance of electrical wiring insulation

  • quantity of galvans in an electric circuit

Explanation

Question 109 of 131

1

Regulations require emergency diesel engine starting systems to have sufficient capacity to provide power for at least ____.

Select one of the following:

  • six consecutive cranking cycles

  • three continuous starting sequences

  • nine repeated starts under load

  • twelve cranking periods of 5 seconds

Explanation

Question 110 of 131

1

In a three-phase, open-delta connected transformer, the line current is equal to ____.

Select one of the following:

  • the phase current

  • three times the phase current

  • the sum of any two phase currents

  • the difference of any two phase currents

Explanation

Question 111 of 131

1

In a running electric motor, why are we using a sound listening bar?

Select one of the following:

  • To detect fault in ball bearing

  • To detect fault in motor windings

  • To detect fault in stator windings

  • To detect if motor is overload

Explanation

Question 112 of 131

1

Why is an armature cores in a DC generator made of laminated steel sheets?

Select one of the following:

  • To reduce eddy current losses

  • To fit the curvature of the frame

  • To increase the hysteresis effect

  • To allow for easy assembly

Explanation

Question 113 of 131

1

What will be the next step after closing the circuit breaker to place two similar alternators in parallel?

Select one of the following:

  • To balance the kilowatt load

  • To maintain the power factor

  • To reduce voltage load

  • To balance ampere load

Explanation

Question 114 of 131

1

What is the reason why one of the generator or motor bearings generally insulated from the end housing?

Select one of the following:

  • To preventcirculation of shaft currents induced in the machine’s frame

  • To prevent excessive field winding heat

  • To remove current leakage from the shaft

  • To minimize rapid brush wear

Explanation

Question 115 of 131

1

Why is a modern DC generators fitted with commutating poles?

Select one of the following:

  • To reduce sparking

  • To prevent motorizing

  • Reduce spring pressures ion the brushes

  • Reduce the load on the main poles

Explanation

Question 116 of 131

1

Why is there an amortisseur windings installed in a synchronous motor?

Select one of the following:

  • To dampen any speed fluctuation as a result of load change

  • To produce a higher power factor

  • produce a higher power factor

  • eliminate arcing between the stator and the rotor

Explanation

Question 117 of 131

1

What is the function of the interpoles installed in DC motors?

Select one of the following:

  • To limit the production of counter electromotive force

  • To provide greater torque by strengthening the main field

  • To limit the starting surge current

Explanation

Question 118 of 131

1

What is the purpose of squirrel-cage windings in a synchronous motor?

Select one of the following:

  • To provide a means for starting

  • To provide more precise balancing

  • To produce a higher power factor

  • To eliminate arcing between the stator and the frame

Explanation

Question 119 of 131

1

When energizing a DC propulsion motor using Local override manual control, What should the variable resistor do?

Select one of the following:

  • Turn to a position which initializes motor rotation and then turn back to the slow position

  • Turn all the way to the full run position then quickly back toslow

  • quickly to the mid position

  • quickly to the full run position

Explanation

Question 120 of 131

1

What is an operating characteristic appearing on the name plates of shipboard AC motors?

Select one of the following:

  • Temperature rise

  • type of overload protection

  • rated slip

  • locked rotor torque

Explanation

Question 121 of 131

1

When mixing electrolyte, which if the following precautions should always be observed?

Select one of the following:

  • Add the acid to the water

  • Use a heavy duty aluminum pail

  • Add the water to the acid

  • Mix the solution outdoors

Explanation

Question 122 of 131

1

If the approximate voltage to be measured in an electric circuit is not known, you should _____.

Select one of the following:

  • use the highest voltage range on the voltmeter

  • Use the lowest voltage range on the voltmeter

  • connect the meter in series with the circuit

  • only have to calibrate the meter before using it

Explanation

Question 123 of 131

1

The basic operating principle of a transformer is attributed to ___.

Select one of the following:

  • electromagnetic induction

  • variance of a conductor in a magnetic fluid

  • mutual reaction

  • thermionic emission

Explanation

Question 124 of 131

1

How is kilowatt load divided between two AC generators operating in parallel?

Select one of the following:

  • Adjusting the governor controls

  • Varying the excitation voltage

  • Increasing both prime mover speeds simultaneously

  • Decreasing both prime mover speeds simultaneously

Explanation

Question 125 of 131

1

An increase in which of the listed conditions will increase the speed of synchronous electric motor?

Select one of the following:

  • Frequency

  • Voltage

  • Armature current

  • Inductance

Explanation

Question 126 of 131

1

Which of the following meters uses a shunt connected in series with the load, but parallel with the meter movement?

Select one of the following:

  • ammeter

  • voltmeter

  • power factor meter

  • wattmeter

Explanation

Question 127 of 131

1

How is the capacity of a storage battery being measured?

Select one of the following:

  • Ampere-hours

  • Volts

  • Volt-hours

Explanation

Question 128 of 131

1

A general purpose electrical multimeter can be used to directly measure ____.

Select one of the following:

  • current

  • watts

  • field flux

  • all of the above

Explanation

Question 129 of 131

1

What is the simplest method of controlling the terminal voltage of compound-wound DC generator?

Select one of the following:

  • With a hand-operated field rheostat connected in series with the shunt field circuit

  • With a separate exciter in series with the shunt field  

  • With a balance coil diverting neutral current through the shunt field

  • With a carbon pile regulator in series with the load

Explanation

Question 130 of 131

1

A ‘dead front’ switchboard is one ____.

Select one of the following:

  • with insulated switches and no exposed terminals

  • without switches on it

  • without circuit breakers

  • without safety hand rail nor rubber mats

Explanation

Question 131 of 131

1

When the feeder system has no ground fault, what does the pointer of the insulation resistance indicates

Select one of the following:

  • Infinity ohm resistance

  • Zero ohm resistance

  • 500 ohm resistance

  • 100 ohm resistance

Explanation

Previous
Check answer
Next