ELECTRICAL 2

Gaviola Jayson, Alab · 100問 · 2年前

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Which of the following is NOT a property of magnetic field lines

The lines cross themselves only at right angles

Chemicals with lower flash points present a greater

Flammability hazard

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

Three phase fault

Which of the following define the meaning of load factor

The ratio of average load to maximum load

What is the maximum speed at which a 60 Hz synchronous machine can be operated

3600 rpm

A substance that changes its electrical resistance when illuminated by light is called

Photoconductive

What does PEMC in EPIRA stands for

Philippine Electricity Market Corporation

The size of conductor on EHV lines is obtained based on

corona

In case of delta connected circuit, when one resistor is open, power will be

reduced by ⅓

Residual magnetism is necessary in a

self excited generator

As load power factor of an alternator becomes more leading, the value of generated voltage required to give rated terminal voltage

decreases

This is the rating of power circuit breakers used to be the basis in replacing its contacts

duty cycle

A device that establishes an electrical connection to the earth

Grounding electrode

What is the primary advantage of FM over AM

Noise immunity

What is the IEEE device function number 21

distance relay

When the length of the wire is doubled and all other factors remained the same, what would the wire resistance become

doubled

If an electrical network having one or more than one voltage source, is transformed into equivalent electrical network with a single current source (which is the short circuit current of previous circuit) with parallel internal resistance of the network with all current source replaced by their internal resistance, this is called:

Norton's Theorem

When the relative permeability of a material is slightly more than 1, it is called

paramagnetic

A coulomb :

is an extremely large number of charge carriers

The conduction of electricity across the surface of a dialectric is called

creepage

The amount of magnetizing force to counter balance the residual magnetism of a magnetic material is reffered to as

coercivity

The transient current in a loss free LC circuit when excited from an ac source is a/an

undamped

For power transformers, the conservator tank is intended to minimize

oil sludging

The efficiency of thermal plant is approximately

30%

A pure semiconductor without doping is called

Intrinsic

A coil that opposes any change in current flow is called a(n)

inductor

If all other factors are held constant, the capacitance between a pair of parallel, flat, identical metal plates

increases as the surface area of the plates increases

In resistance welding, the SCR is closed during _____ time

weld

The overcurrent protective device is caused to operate by

current flow

In a transformer, the resistance between the primary and secondary must be

infinite

While describing the sheath of a cable, the abbreviation XLPE means __________ polyehtylene

cross linked

In the differential current protection system, the current transformer secondaries of wye delta power transformer will be in

delta-wye

A __________ is an electrical device that prevents an electrocution caused by an accident or equipment malfunction

ground fault circuit interrupter

When a current carrying conductor is brought into a magnetic field, the force that moves the conductor depends upon the ____

the value of current

Which of the following types of heating process is used for surface hardening of the steel

induction

As instrument having a voltage coil and a current coil would be a

wattmeter

The calculation of the reliability indices of the grid owners as set by Philippine Grid Code shall include outages that occur

on the transmission line

Two small charged objects attract each other with a force F when separeted by a distance d. If the charge on each object is reduced to one fourt of its original value and the distance between them is reduced to d/2 the force becomes

F/4

Two charge point particles are located at two vertices of an equilateral triangle and the electric field is zero at the third vertex. We conclude:

at least one other charged particle is present

Two identical capacitors, each eith capacitance C, are connected in parallel and the combination is connected in series to a third identical capacitorm The equivalent capacitance of this arrangement is :

2C/3

Conduction electrons move to the right in a certain wire. This indicated that

The current density and electric field both point left

Ohm's law is not applicable to

silicon carbide

A test used to determine the equivalent resistance of an induction motor is

blocked rotor test

Power lost due to alternating magnetization and demagnetization of the core material

hysteresis loss

A transformer has negative voltage regulation when its power factory is

leading

For the two conductors inside the conduit, the ampacity of the conductors shall be derated to what percent

none of these

A device or equipment which is suspended from overhead either by means of a flexible cord carrying the current or otherwise

Pendant

Which part of the human body offers the most resistance to electricity

Thick and or dry skin

What is ACSR conductor stand for

Aluminum Cable Steel Reinforced

The resistance of the rod does NOT depend on:

the shape of its (fixed) cross-sectional area

The electrical analog of a spring constant k is:

1/C

Which transformer has only one winding

autotransformer

A multimeter is connected to one terminal of primary and other terminal of secondary to measure resistance. The multimeter reading would be

infinity

Amplitude modulation generated at a very low voltage or power amplitude is known as

Low level modulation

For an unbalanced load, which connection is suitable

4 wire wye connection

The effect of electric shock in the human body will depend on

current flowing in the body

In two-wattmeter method, the readings if the wattmeters will be identical when

power factor is unity

The function of a surge tank is

to relieve water hammer pressures in the penstock pipe

For measuring current at high frequency, we should use

thermocouple

The tesla is a unit of

Magnetic flux density

Which is the most suitable for punch presses

cumulatively compounded motor

Transient response in the system is basically due to

Stored energy

Conventional or VRE Embedded Generating Plants with Installed Capacity larger than 100 kW and equal to of less than 1 MW

Intermediate

Which of the following will need lowest level of illumination

Railway platform

What classification is given to a d.c generator that receives its field excitation current from internal source?

self excited

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

Induction generators deliver power at

Leading power factor only

This is an electrically operated switch which is rated in amperes and is also used in overload protection of motors

magnetic contactor

The commonly used light sensor in a modern fax machine is the

charge couple device

A frequency of 27 MHz has a wavelength if approximately

11 m

One of those listed is not a type of dc generator winding

progressive

A semiconductor frequently used to rectify AC current to DC is called

diode

Resistors commonly used in power circuits are

wire wound resistors

If the field of a dc shunt motor is opened

the speed of the motor will become very high

Which of the following is NOT INCLUDED in the Technical Performance Standards for Distribution and Supply set by the Philippine Distribution Code

Collection Efficiency

The form factor of dc supply voltage is always

unity

What is the IEEE device function number 50

Instantaneous overcurrent relay

What type of core is used for a high frequency transformer

air core

Megger essentially is a

megohmmeter

Whrn a conductor is stationary and the magnetic field is moving or changing, the emf induced is called

Statically induced emf

The surge impedance of a transmission line differs from its characteristics impedance, as surge impedance considers line

resistance of finite value

Three phase transformers which cannot be connected in parallel are

YY with Y ∆

The wire with the highest temperature rating is

THHN

The maximum rating of the overcurrent device for a branch circuit supplying a nonmotor-operated appliance that draws 20 amperes is

30 amperes

A capacitor C "has a charge Q". The actual charges on its plates are

Q3 -Q

An electrical cooperative is a cooperative or corporation authorized to provide electric services pursuant to Presidential Decree No.269, as amended, and Republic Act No. ________ within the framework of the national rural electrification plan

6938

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

Photoconductive

A fuel cell in order to produce electricity burns

Hydrogen

The volume of copper required for an ac transmission line is inversely proportional to

BOTH B AND C

The law that induces emf and current always opposes the cause producing them was discovered by

Lenz

Series capacitors are used to

compensate for line inductive resistance

Surge impendance of transmission line is given by

√L/C

Which of the following distribution systems gives the greater reliability

ring system

The transformer oil used in transformers provide

insulation and cooling

To protect the ∆-∆ power transformer against fault, the CT will have

Y-Y connection

For a detection of the occurance of the severe synchronizing power surges

MHO relays are best suited

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

Diesel power plant

If the capacitance of the transmission line is increased, the transmitted power will

increase

Which of the following tests are conducted for transformer oil? I - Dialectric II - Interfacial tension III - Color of oil IV - Neutralization number V - Power factor VI - Specific gravity

II , III, IV ,and V

100

Peak load plants are designed to supply power at

low capital cost and high operating cost

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