ELECTRICAL 1

100問 • 2年前

問題一覧

A PERMEABLE (NATATAGUSAN) SUBSTANCE IS ONE

through which the magnetic lines of force can pass very easily

the customer is only charged or credited as the case may be, for the difference between the electricity supplied by the distribution utility and electricity it supplies to the distribution utility when the times it has excess VRE generation both of which are using either 2 unidirectional meters one for import and for export or a single bidirectional meter

Net Metering

Electric Field lines are close together where the field is large

true

If a tropical storm is going to the Philippine Area of Responsibility within 24 hours what type of alert is to be raised in accordance with the Philippine Grid Code

Blue Alert

for any circuit the number of independent equations containing emfs resistances and currents equals the number of ______

branches

In the context of the loop and junctions rules for electrical circuits a junction is where_____

three or more wires are joined

which of the following statement is false

windows 98 is RTOS

Determine the GMR of a three-equal strands conductors in vertical formation in terms of r of an individual strand

1.7036 r

A cylindrical copper rod has resistance R. It is reformed to twice its original length with no change in volume. What is its new resistance?

DMC stands for? created by ERC in compliance to PDC

Distribution Management Committee

the rms value value of ac current is

that steady current that produces the same rate of heating in resistor as the actual current.

it refers to the powerloss due to alternating magnetization and demagnetization of the core material

hysterisis loss

Which of the following is the following is the correct statement about coulomb?

the amount of charge that flows a past point in one second when the current is one ampere

When a dc motor has no load, what will happen to the back emf?

becomes maximum

synchronizing power of a synchronous machine is

inversely proportional to the synchronous reactance

It is a device which functions on failure of a machine, transformer or of other apparatus to ground or on flash over of a dc machine to ground

ground protective relay

the total load on any overcurrent device located in a panelboard shall not exceed ___ of its rating where the normal operation the load will continue for three hours or more

80%

the region or area in a transistor that is heavily doped

emitter

GMC was created by the Energy Regulatory Commision to monitor the compliance of the users of the Grid to the PGC. What does the GMC stands for?

Grid Management Committee

It is possible to increase the field flux and, at the same time, increase the speed of a dc motor provided its _______ is held constant

Armature current

It is considered as the heart of a dc machine

Armature winding

While describing the shealth of a cable, the abbreviation XLPE means _____________ polyethylene

cross-linked

Conductors supplying two or more motors shall have an ampacity equal to the sum of the following current rating of all the motors plus ______% of the highest rated motor in the group

Megger essentially is a

megohmmeter

Which of the following cannot have a single unit of 100 MW

Diesel power plant

Chemicals with lower flash points presents a greater ______

Flammability hazard

What is the maximum number of conductors in a raceway that does not need to be derated

Which of the following type of fault used only the equivalent positive sequence impedance of the circuit in the short circuit calculation

Three phase fault

Which of the following insulators will be selected for high voltage application

Suspension type

Base load plants are designed to supply power at

high capital cost and low operating cost

Which is not a characteristics of an ideal transformer

finite permeability

What is the IEEE device function number 50

Instantaneous overcurrent relay

Transformer breaths in when

load on it decreases

The color reserved for use in equipment grounding conductor is

Green

Joule found out that the heat produced in a current carrying conductor is proportional to

the square of the current

The applied voltage in a transformer is increased by 50% and frequency is reduced by 50%. The maximum core flux density will become

3 times

A battery is used to change a parallel plate capacitor, after which it is disconnected.Then the plates are pulled apart to twice their original separation. This process will double the :

Stored energy

A step-down transformer is used to

decrease the voltage

Iron, rather than copper, is used in the core of transformers because iron:

has a very high permeability

The tesla is a unit of

magnetic flux density

Which of the following statements regarding the motion of a conductor through a changing magnetic field is FALSE

The conductor must move at constant velocity in order to generate a current

A DC system can be protected from lightning by including a thyrite tube in the circuit that connects the high voltage line with the ground. Which of the following is FALSE regarding a thyrite tube?

Its fusable link melts at high voltages

Which of the following statements regarding transformer is FALSE

One three phase transformer weighs more than three equivalent single phase transformer

For an existing a.c. transmission line the string efficiency is 80%. Now if d.c voltage is supplied for the same set up, the string efficiency will be:

100%

The inductance per unit length of an overhead line due to internal flux linkages

Is independent of the size of conductor and constant

High permittivity ceramic is used for capacitors of

A few uF to a few hundred uF

What are the causes of gross error in the instrument 1. Misreading of instruments 2. Incorrect adjustment of instruments 3.Errors due to defective instruments 4.Errors due to effort of environment on the instrument

1 and 2

The phase shift between the current and voltage vectors is due to the following except one

electric flat iron

An aternating voltage is given by v=100 sin 314t volts. Its average value will be

63.7 V

It is desired to have a constant direct current i(t) through the ideal inductor L. The nature of the voltage source v(t) must

an ideal impulse

The ordinary efficiency of a given transformer is maximum when

its Cu loss equals iron loss

Receptacles installed on 15- and 20- ampere branch circuits must always be of what type

Grounding type

In a circuit breaker the time duration from the instant of energizing of the trip coil is known as

protection time

Over voltage protection is recommended for

All of these

What is the fourth harmonic of 800 KHZ

3.20 MHZ

The fuse used for the overhead primary distributors is

expulsion

Peak load plants are designed to supply power at

low capital cost and high operating cost

Which of the following principle will the operation of fiber optic cable is based

reflection

In a wye connected system, line current is

equal to the phase current

A device that establishes an electrical connection to the earth

Grounding electrode

What determines the direction of force in a conductor

Left hand rule

In a parallel circuit, the potential difference across the resistance

is always constant

Based on the Philippine Distribution code (PDC), the Distributor may establish penalties for Users whose power factors are less than

85%

An Act to ensure and accelerate the total electrification of the Philippines, also known as EPIRA law of 2001

RA 9136

If we increase field current of a dc generator, its emf output

increases till the magnetic saturation takes place

Armature reaction in an alternator primarily affects

generated voltage per phase

What is the equivalent of the collector terminal of transistor in a FET

Drain

Branch circuit conductors supplying a single motor shall have an ampacity NOT less than _____ percent of the motor full load current rating

125

Ten oersted is equivalent to

0.1cm/GB

The transients which are produced due to sudden but energetic changes from one steady state of a circuit to another are called

Transition

The relative polarity of the winding of a transformer may be determined by

phasing out

When luminaires direct 90 to 100% of their output upward is considered a

Indirect lighting

Which of the following limits the number of coils that may be placed on the armature of a DC motor or generator

coil to coil arcing due to the breakdown of insulation

A transformer has negative voltage regulation when its power factor is

leading

When a step input is applied to a second order circuit, the final values of the circuit variables are found by

Replacing capacitors with open circuits and inductors with closed circuits

Power factor can be improved by connecting which among these

Static capacitors and synchronous condensers

Which of the following is NOT a reason why single-phase induction motor run

hysteresis

What is the device function number of overvoltage relay

"Debye" is the unit of

Electric dipole moment

Relay used for feeder protection is

translay relay

Electric hazards include shock, electric arcs and blasts and ____ or faulty equipment

Broken

The resistance of a semiconductor is known as

bulk resistance

What does the fourth loop of an electronic resistor color code represent

Tolerance

Auxiliary gutters shall not contain more than ______ current carrying conductors at any cross section

In the list below, which ine is not a type of present day nuclear power plant

fussion fission reactor

The ratio of the average load on the plant for the period of time considered to the aggregate rating of all the generating equipment

Capacity factor

In an ideal transformer

All of these

The full load copper loss in a transformer is 400 watts. At half load, the copper loss will be

100 watts

In a HRC fuse the time between cut-off and final current zero, is known as

arcing time

The advantage of the ring main system is

Continuity of supply to feeding points

When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor

increases to two times the original value

The imaginary or fictitious part of synchronous reactance takes care of

armature reaction

The electrical analog of a spring constant k is:

1/C

A 2-uF and a 1-uF capacitor are connected in series and a potential difference is applied across the combination. The 2 -uF capacitor has

half the potential difference of the 1-uF capacitor

A "coulomb" is

the amount of charge that flows past a point in one second when the current is 1 A

The tesla is a unit of

magnetic flux density

Induction generators deliver power at

Leading power factor only

The wire with the highest temperature rating is

THHN

As substance that changes it electrical resistance when illuminated by light is called

Photoconductive

100

A resistor with colour bands: red-red-red-gold has the value

2k2 5%

M#5 Section and Title v2

ユーザ名非公開 · 32問 · 13日前

M#5 Section and Title v2