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

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Questão 1 de 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?

Selecione uma das seguintes:

  • 4.5 amps

  • 1.1 amps

  • 18.1 amps

  • 27.7 amps

Explicação

Questão 2 de 131

1

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

Selecione uma das seguintes:

  • 2.0 volts

  • 2.3 volts

  • 1.5 volts

  • 1.8 volts

Explicação

Questão 3 de 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.

Selecione uma das seguintes:

  • 9.8 and 10.2 milliamperes

  • 8.0 and 12.0 milliamperes

  • 9.8 and 10.0 milliamperes

  • 8.0 and 10.0 milliamperes

Explicação

Questão 4 de 131

1

Basic electrical motor action depends on_______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 5 de 131

1

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

Selecione uma das seguintes:

  • DC voltage to the field

  • AC voltage to the armature

  • AC voltage to the field

  • DC voltage to the armature

Explicação

Questão 6 de 131

1

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

Selecione uma das seguintes:

  • resistance

  • amperage

  • inductance

  • capacitance

Explicação

Questão 7 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 8 de 131

1

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

Selecione uma das seguintes:

  • main switchboard

  • bridge control panel

  • disconnect links

  • governor relay box

Explicação

Questão 9 de 131

1

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

Selecione uma das seguintes:

  • direct connections from the stator

  • brushes on slip rings

  • brushes on a commutator

  • slip rings on a commutator

Explicação

Questão 10 de 131

1

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

Selecione uma das seguintes:

  • explosive gases

  • corrosive gases

  • highly poisonous gas

  • highly combustible oxygen

Explicação

Questão 11 de 131

1

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

Selecione uma das seguintes:

  • explosive gases

  • corrosive gases

  • highly poisonous gas

  • highly combustible oxygen

Explicação

Questão 12 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 13 de 131

1

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

Selecione uma das seguintes:

  • transformer

  • diode

  • transistor

  • rheostat

Explicação

Questão 14 de 131

1

Amortisseur windings are installed in a synchronous motor to_____.

Selecione uma das seguintes:

  • provide a means for starting

  • eliminate arcing between the stator and the rotor

  • produce a higher power factor

  • reduce eddy current losses

Explicação

Questão 15 de 131

1

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

Selecione uma das seguintes:

  • Slip rings

  • End rings

  • A centrifugal switch

  • End plates

Explicação

Questão 16 de 131

1

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

Selecione uma das seguintes:

  • inductive reaction of the rotating stator field

  • external variable resistors

  • slip rings and brushes

  • an armature and brushes

Explicação

Questão 17 de 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 ________.

Selecione uma das seguintes:

  • voltage regulator

  • governor speed droop setting

  • balance coil

  • phase-balance relay

Explicação

Questão 18 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 19 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 20 de 131

1

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

Selecione uma das seguintes:

  • increase the speed of the prime mover

  • increase the field excitation

  • decrease the field excitation

  • increase the number of magnetic poles

Explicação

Questão 21 de 131

1

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

Selecione uma das seguintes:

  • interlock

  • limit

  • monitor

  • modulator

Explicação

Questão 22 de 131

1

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

Selecione uma das seguintes:

  • start the motor

  • limit the starting voltage

  • increase the starting current

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

Explicação

Questão 23 de 131

1

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

Selecione uma das seguintes:

  • line loss

  • line droop

  • IR drop

  • hysteresis

Explicação

Questão 24 de 131

1

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

Selecione uma das seguintes:

  • absorption of moisture in the insulation

  • loss of residual magnetism

  • insulation varnish flaking

  • dirt collecting on the windings

Explicação

Questão 25 de 131

1

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

Selecione uma das seguintes:

  • ship's service alternator

  • magnetic amplifier

  • three-wire DC generator

  • saturable core reactor

Explicação

Questão 26 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 27 de 131

1

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

Selecione uma das seguintes:

  • ohms

  • mhos

  • henrys

  • farads

Explicação

Questão 28 de 131

1

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

Selecione uma das seguintes:

  • relative speed of the rotor poles

  • number of turns of wire in the armature coil

  • strength of the magnets used

  • output voltage

Explicação

Questão 29 de 131

1

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

Selecione uma das seguintes:

  • Synchronous

  • Polyphase

  • Wound-rotor

  • Induction

Explicação

Questão 30 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 31 de 131

1

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

Selecione uma das seguintes:

  • voltage regulator

  • reverse power relay

  • exciter generator

  • prime mover governor

Explicação

Questão 32 de 131

1

The capacity of a storage battery is measured in_______.

Selecione uma das seguintes:

  • ampere-hours

  • volts

  • farads

  • amps

Explicação

Questão 33 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 34 de 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_______ .
.
"

Selecione uma das seguintes:

  • voltage regulator

  • governor speed droop setting

  • balance coil

Explicação

Questão 35 de 131

1

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

Selecione uma das seguintes:

  • Reduce

  • Increase

  • Stop

  • No adjustment needed

Explicação

Questão 36 de 131

1

External shunts are sometimes used with ammeters to _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 37 de 131

1

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

Selecione uma das seguintes:

  • Change the input frequency of the voltage to the motor

  • Increase the motor voltage

  • Decrease the motor voltage

Explicação

Questão 38 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 39 de 131

1

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

Selecione uma das seguintes:

  • resistance

  • inductance

  • capacitance

  • amperage

Explicação

Questão 40 de 131

1

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

Selecione uma das seguintes:

  • Shunt field coils

  • Inertia poles

  • Stator

  • Frame

Explicação

Questão 41 de 131

1

How does the speed of a synchronous motor change?

Selecione uma das seguintes:

  • Changing the input frequency

  • Interchanging any tow of the three live leads

  • Changing the voltage of the system

  • Increasing the field excitation

Explicação

Questão 42 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 43 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 44 de 131

1

Power transformers are rated in _____.

Selecione uma das seguintes:

  • kilovoltamperes

  • kilowatt-amps

  • ampere-turns

  • kilowatt-volts

Explicação

Questão 45 de 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 _____.

Selecione uma das seguintes:

  • unity

  • lagging

  • leading

  • infinity

Explicação

Questão 46 de 131

1

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

Selecione uma das seguintes:

  • maximum

  • lagging

  • leading

  • minimum

Explicação

Questão 47 de 131

1

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

Selecione uma das seguintes:

  • electromagnets

  • line voltage

  • a separate battery source

  • the main bus

Explicação

Questão 48 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 49 de 131

1

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

Selecione uma das seguintes:

  • speed droop

  • Load limit

  • idle speed

  • speed limit

Explicação

Questão 50 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 51 de 131

1

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

Selecione uma das seguintes:

  • Reversed interpole polarity

  • Low series field current

  • High shunt field current

  • Excessive humidity

Explicação

Questão 52 de 131

1

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

Selecione uma das seguintes:

  • No load

  • Low speed

  • High speed

  • Medium speed

Explicação

Questão 53 de 131

1

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

Selecione uma das seguintes:

  • DC rectifier

  • Low voltage battery

  • Motor attenuator set

  • AC supply

Explicação

Questão 54 de 131

1

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

Selecione uma das seguintes:

  • Reverse current relays

  • Main bus disconnect links

  • A separate battery back-up

  • Reverse power relays

Explicação

Questão 55 de 131

1

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

Selecione uma das seguintes:

  • motor starting circuit

  • main lighting circuits

  • emergency lighting circuits

  • general alarm circuits

Explicação

Questão 56 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 57 de 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?

Selecione uma das seguintes:

  • Clamp meter

  • Meager tester

  • Ammeter

  • Multi tester

Explicação

Questão 58 de 131

1

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

Selecione uma das seguintes:

  • fewer turns

  • more turns

  • same number of turns but smaller wires

  • twice as many turns

Explicação

Questão 59 de 131

1

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

Selecione uma das seguintes:

  • Direction of rotation will be reversed

  • Motor will not run

  • Direction of rotation will be the same

  • Motor will run as a generator

Explicação

Questão 60 de 131

1

What is the purpose of DC generator brushes?

Selecione uma das seguintes:

  • Conduct electric current to an outside current

  • Neutralize armature reaction

  • Convert DC current to AC current

  • Provide excitation to a DC generator

Explicação

Questão 61 de 131

1

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

Selecione uma das seguintes:

  • Frequency meter

  • Ohmmeter

  • Induction voltage regulator

  • Current transformer governor

Explicação

Questão 62 de 131

1

A bus disconnect link is used to isolate ___.

Selecione uma das seguintes:

  • 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

Explicação

Questão 63 de 131

1

The purpose of a magnetic relay is to ______.

Selecione uma das seguintes:

  • remotely open and close contacts

  • open a circuit only in the event of overload

  • provide overcurrent protection during starting

  • relay voltages at increased power

Explicação

Questão 64 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 65 de 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?

Selecione uma das seguintes:

  • Limit switches

  • Overlap sensors

  • Differential relays

  • Analog relays

Explicação

Questão 66 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 67 de 131

1

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

Selecione uma das seguintes:

  • the secondary coil

  • part of the core

  • the primary coil

  • not insulated

Explicação

Questão 68 de 131

1

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

Selecione uma das seguintes:

  • Charging rate is excessive

  • Plate separators are grounded

  • Cell voltages are excessive

  • Specific gravity is insufficient

Explicação

Questão 69 de 131

1

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

Selecione uma das seguintes:

  • Overcurrent tripping device

  • Preferential tripping system

  • Time delay trip device

  • ACB trip device

Explicação

Questão 70 de 131

1

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

Selecione uma das seguintes:

  • To filter out ripple for rectification

  • prevent overloads

  • act as a permanent load

  • decrease the average value of the output voltage

Explicação

Questão 71 de 131

1

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

Selecione uma das seguintes:

  • Step-up transformer

  • Primary transformer

  • Secondary transformer

  • Step-down transformer

Explicação

Questão 72 de 131

1

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

Selecione uma das seguintes:

  • Voltage regulators

  • Prime mover governors

  • Proportioner

  • Phase balance relay

Explicação

Questão 73 de 131

1

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

Selecione uma das seguintes:

  • connected load

  • prime mover speed

  • ground current

  • generator’s rated voltage

Explicação

Questão 74 de 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?

Selecione uma das seguintes:

  • Locked rotor torque

  • Pullout torques

  • Breakdown torque

  • Torque margin

Explicação

Questão 75 de 131

1

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

Selecione uma das seguintes:

  • Reverse its two-pole field

  • Reduce the power consumed

  • Change its impedance

  • Reduce the amount of flux produced

Explicação

Questão 76 de 131

1

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

Selecione uma das seguintes:

  • A mechanical prime mover

  • Residual magnetism in the armature

  • Residual magnetism in the field poles

  • Residual magnetism in voltage regulator

Explicação

Questão 77 de 131

1

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

Selecione uma das seguintes:

  • prime mover governors

  • reverse power relays

  • field rheostat

  • voltage regulators

Explicação

Questão 78 de 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?

Selecione uma das seguintes:

  • Raise the generator engine speed

  • Rotate brush alignment

  • Decrease excitation

  • Lower the generator engine speed

Explicação

Questão 79 de 131

1

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

Selecione uma das seguintes:

  • Exciter

  • Rotor

  • Stator

  • Armature

Explicação

Questão 80 de 131

1

Transformer cores are laminated to reduce ____.

Selecione uma das seguintes:

  • eddy currents

  • secondary flux

  • leakage flux

  • tertiary flux

Explicação

Questão 81 de 131

1

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

Selecione uma das seguintes:

  • The push button switch

  • Selector switch

  • Micro switch

  • Lamp switch

Explicação

Questão 82 de 131

1

A transformer works on the basic principle of ____.

Selecione uma das seguintes:

  • mutual induction

  • self impedance

  • attraction and repulsion

  • increasing power

Explicação

Questão 83 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 84 de 131

1

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

Selecione uma das seguintes:

  • Compound-wound motor

  • Series-wound motor

  • Shunt-wound motor

  • Induction motor

Explicação

Questão 85 de 131

1

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

Selecione uma das seguintes:

  • Universal motor

  • Series-wound motor

  • Synchronous speed motor

  • Regulated speed motor

Explicação

Questão 86 de 131

1

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

Selecione uma das seguintes:

  • open circuit

  • short circuit

  • bonded circuit

  • grounded circuit

Explicação

Questão 87 de 131

1

How would you describe a circuit with a blown fuse?

Selecione uma das seguintes:

  • Open circuit

  • Short circuit

  • Bonded circuit

  • Grounded circuit

Explicação

Questão 88 de 131

1

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

Selecione uma das seguintes:

  • Series

  • Shunt

  • Cumulative-compound

  • Differential-compound

Explicação

Questão 89 de 131

1

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

Selecione uma das seguintes:

  • band markings on the resistor

  • single solid body color of the resistor

  • amperage value written on the resistor

  • physical size of the resistor

Explicação

Questão 90 de 131

1

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

Selecione uma das seguintes:

  • Slightly greater than the line frequency

  • Slightly less than the line frequency

  • The same as the line frequency

  • Greater than the line frequency

Explicação

Questão 91 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 92 de 131

1

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

Selecione uma das seguintes:

  • Harder than copper

  • Softer than copper

  • Same hardness as copper

  • Softer than copper but wears away at slower rate

Explicação

Questão 93 de 131

1

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

Selecione uma das seguintes:

  • Slip of the rotor

  • Speed of the rotating field

  • DC filed excitation

  • Current flow in the interpoles

Explicação

Questão 94 de 131

1

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

Selecione uma das seguintes:

  • Series-wound

  • split-phase

  • Shaded-pole

  • Repulsion-start

Explicação

Questão 95 de 131

1

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

Selecione uma das seguintes:

  • Wound rotor induction motor

  • Squirrel cage induction motor

  • Regenerative braking motor

  • Squirrel-cage induction motor

Explicação

Questão 96 de 131

1

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

Selecione uma das seguintes:

  • DC supply

  • Step-up transformer

  • AC supply

  • Poor contact of brushes

Explicação

Questão 97 de 131

1

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

Selecione uma das seguintes:

  • Autotransformers

  • Step up transformers

  • Stepdown transformers

  • Isolation transformers

Explicação

Questão 98 de 131

1

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

Selecione uma das seguintes:

  • Series

  • Synchronous

  • Cage

  • Shunt

Explicação

Questão 99 de 131

1

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

Selecione uma das seguintes:

  • Watertight motors

  • Synchronous motors

  • Drip proof motors

  • Squirrel cage motors

Explicação

Questão 100 de 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?

Selecione uma das seguintes:

  • The capacitance of the circuit

  • The dielectric absorption effect of the insulation

  • The leakage of current along the surface of dirty insulation

  • Good insulation

Explicação

Questão 101 de 131

1

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

Selecione uma das seguintes:

  • 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.

Explicação

Questão 102 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 103 de 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_______.

Selecione uma das seguintes:

  • a percent of synchronous speed

  • the reduced amp rating

  • the decrease in shaft torque

  • reduced fuel consumption

Explicação

Questão 104 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 105 de 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?

Selecione uma das seguintes:

  • 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

Explicação

Questão 106 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 107 de 131

1

What is the advantage of DC motors over AC motors?

Selecione uma das seguintes:

  • Offer infinite speed variations

  • They are less expensive

  • They require less maintenance

  • They offer slow speed

Explicação

Questão 108 de 131

1

A galvanometer is an instrument used to measure ____.

Selecione uma das seguintes:

  • very small amounts of current or voltage

  • thickness of galvanized metal

  • resistance of electrical wiring insulation

  • quantity of galvans in an electric circuit

Explicação

Questão 109 de 131

1

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

Selecione uma das seguintes:

  • six consecutive cranking cycles

  • three continuous starting sequences

  • nine repeated starts under load

  • twelve cranking periods of 5 seconds

Explicação

Questão 110 de 131

1

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

Selecione uma das seguintes:

  • the phase current

  • three times the phase current

  • the sum of any two phase currents

  • the difference of any two phase currents

Explicação

Questão 111 de 131

1

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

Selecione uma das seguintes:

  • To detect fault in ball bearing

  • To detect fault in motor windings

  • To detect fault in stator windings

  • To detect if motor is overload

Explicação

Questão 112 de 131

1

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

Selecione uma das seguintes:

  • To reduce eddy current losses

  • To fit the curvature of the frame

  • To increase the hysteresis effect

  • To allow for easy assembly

Explicação

Questão 113 de 131

1

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

Selecione uma das seguintes:

  • To balance the kilowatt load

  • To maintain the power factor

  • To reduce voltage load

  • To balance ampere load

Explicação

Questão 114 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 115 de 131

1

Why is a modern DC generators fitted with commutating poles?

Selecione uma das seguintes:

  • To reduce sparking

  • To prevent motorizing

  • Reduce spring pressures ion the brushes

  • Reduce the load on the main poles

Explicação

Questão 116 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 117 de 131

1

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

Selecione uma das seguintes:

  • To limit the production of counter electromotive force

  • To provide greater torque by strengthening the main field

  • To limit the starting surge current

Explicação

Questão 118 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 119 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 120 de 131

1

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

Selecione uma das seguintes:

  • Temperature rise

  • type of overload protection

  • rated slip

  • locked rotor torque

Explicação

Questão 121 de 131

1

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

Selecione uma das seguintes:

  • Add the acid to the water

  • Use a heavy duty aluminum pail

  • Add the water to the acid

  • Mix the solution outdoors

Explicação

Questão 122 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 123 de 131

1

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

Selecione uma das seguintes:

  • electromagnetic induction

  • variance of a conductor in a magnetic fluid

  • mutual reaction

  • thermionic emission

Explicação

Questão 124 de 131

1

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

Selecione uma das seguintes:

  • Adjusting the governor controls

  • Varying the excitation voltage

  • Increasing both prime mover speeds simultaneously

  • Decreasing both prime mover speeds simultaneously

Explicação

Questão 125 de 131

1

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

Selecione uma das seguintes:

  • Frequency

  • Voltage

  • Armature current

  • Inductance

Explicação

Questão 126 de 131

1

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

Selecione uma das seguintes:

  • ammeter

  • voltmeter

  • power factor meter

  • wattmeter

Explicação

Questão 127 de 131

1

How is the capacity of a storage battery being measured?

Selecione uma das seguintes:

  • Ampere-hours

  • Volts

  • Volt-hours

Explicação

Questão 128 de 131

1

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

Selecione uma das seguintes:

  • current

  • watts

  • field flux

  • all of the above

Explicação

Questão 129 de 131

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 130 de 131

1

A ‘dead front’ switchboard is one ____.

Selecione uma das seguintes:

  • with insulated switches and no exposed terminals

  • without switches on it

  • without circuit breakers

  • without safety hand rail nor rubber mats

Explicação

Questão 131 de 131

1

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

Selecione uma das seguintes:

  • Infinity ohm resistance

  • Zero ohm resistance

  • 500 ohm resistance

  • 100 ohm resistance

Explicação