COMPETENCE 6

50問 • 2年前

Peter j Zuniega

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問題一覧

Electric propulsion coupling excitation is reduced at slow speed to ________ .

prevent coupling overheating

An electric tachometer receives the engine speed signal from a_______

small generator mounted on the engine

Moisture as a result of condensatio occurring inside of the cargo winch master switches, can be reduced by______ .

using strip heaters inside the switch box

Which of the following conditions will occur if the solenoid coil burns on a cargo winch with an electrical brake?

The brake will be set by spring force

The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the____ .

exciter output voltage

Which of the following statements represents an application of a silicon controlled rectifier?

To provide DC power for a main propulsion motor.

Autotransformer starters or compensators are sometimes used with polyphase induction motors to_______ .

reduce the voltage applied to the motor during the starting period

Which of the listed devices is used to measure pressure and convert it to an electrical signal?

Transducer

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

relative speed of the rotor poles

Line losses in a distribution circuit are kept to a minimum by _____.

using higher voltage and lower current

A change in field excitation of an alternator operating in parallel will cause change in its _____.

reactive power

Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?

Increased ambient temperature decreases the service life of electronic components.

Two AC generators of the same capacity are operating in parallel. One with zero speed droop setting and the other with a 5% speed droop. If its capacity is not exceeded, the unit whose governor has a zero speed droop setting will ____.

maintain the frequency of the system

An adjustable resistor, whose resistance can be changed without opening the circuit in which it is connected, is called a ____.

rheostat

Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase?

Conductivity will increase

As an armature revolves within a magnetic field, friction is developed between the rotated magnetized particles as they pass though each magnetization cycle. This results in ____.

hysteresis loss

A device used in an electrical circuit to change alternating current to direct current, is known as a______.

rectifier

A silicon controlled rectifier (SCR) is a solid state device used to change_______.

AC to DC and control relatively high load current

Which of the following actions must be carried out prior to closing the alternator circuit breaker?

Increase the alternator voltage

The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____.

directing the arc into an arc chute

Which of the following represents a characteristic of an ungrounded electrical distribution system?

Accidental contact between one line and ground does not cause an outage

When two generators are operating in parallel, what will first occur if the engine driving generator #1 suddenly loses power?

Generator #2 will motorize

Regarding and 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 for by the ____.

voltage regulator

For practical purposes, in a simple series circuit employing two resistors, a drop of one half the source voltage will occur across one resistor if it has _____.

a resistance equal to the other

The mandatory operating characteristic of a pure amplifiers the______. I. form of the input and output energy must be the same II. ratio of the output change to input change must be a value greater than 1(one)

A. I only

An alternator is being paralleled with one on the line. At the INSTANT the circuit. breaker is closed, the frequency of the incoming alternator will normally ____.

decrease

As load is added to an AC generator provided with constant field excitation, the prime mover slows down with the effect of ___.

lowering frequency and lowering generated voltage

The existing resistance of conductor is dependent upon its length, cross-sectional area ____.

material and temperature

Although saturable reactors are extremely useful in some applications, their gain is low because of _____.

core hysteresis losses

The resistance of a conductor varies ______.

directly as its length and inversely as its cross‐sectional area

A resistor placed in parallel to the output of a power supply______.

aids in output voltage regulation

You have installed a Zener diode in parallel with a load. While measuring the voltage across the Zener diode it is found that it does not change as the current through the load increases. This means that the Zener diode_______.

is working as it should

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

line loss

The timer element found in a reverse power relay obtains it operating torque via ___

a separate battery source

Materials that retain a large part of their magnetization, after the magnetizing force is removed, are said to have ______.

high permanence

A current-carrying conductor makes accidental contact with a wiring conduit. This will be indicated by a ___.

darkened switchboard ground detecting lamp

AC generator are protected against malfunctions due to prime mover power loss by the use of ____.

reverse power relays

Nickel‐cadmium batteries are superior to lead‐acid batteries at high discharge rates because they ____.

deliver a large amount of power and can be recharged in a shorter time

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

Frequency meter

Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in _____.

henrys

The timer element of a reverse power relay cannot be energized unless ___.

the power flow is the same as the tripping direction

The purpose of a magnetic relay is to ______.

remotely open and close contacts

Inductance is the property of an electric circuit that _____.

opposes any charge in the current flow through the circuit

To minimize magnetic field interaction between electrical conductors in physical proximity, it is best to keep them ______.

at right angles and as far as practicable from each other

If a shipboard AC generator experiences voltage failure, the cause may be due to ____.

an open in the rotor field circuit

Motorization of an AC generator is undesirable because ____.

it puts an excessive load on the bus

An autotransformer is equipped with a 50% tap, a 65% tap and an 80% tap. Which of the following statements is true concerning a load connected to 50% tap?

The load is receiving minimum voltage and maximum current

The amount of voltage induced in the stator windings of a modern AC generator depend mainly on ____.

the strength of the magnetic field

Silicon diodes which are designed for a specific reverse breakdown voltage, and are most often used in electronic power supply voltage regulators, are called________.

Zener diodes

The purpose of the automatic bus transfer is to ____.

provide emergency power to the lighting distribution panel

COMPETENCE 1