W/M S-4

17/B/C/S-4/4/EPAPER -1

In a transformer the energy is conveyed from primary to secondary___
a) Through cooling coil b) Through air
c) By the flux d) None of these

A transformer core is laminated to_.
a) Reduce Hysteresis Loss b) Reduce Eddy Current Losses
c) Reduce Copper Losses d) Reduce All Above Losses

The path of a magnetic flux in a transformer should have_
a) High resistance b) High reluctance
c) Low resistance d) Low reluctance

The dielectric strength of transformer oil is expected to be___.
a) IkV b) 33 kV c) 100 kV d) 330 kV

The purpose of providing an iron core in a transformer is to
a) Provide support to windings
b) Reduce hysteresis loss
c) Decrease the reluctance of the magnetic path
d) Reduce eddy current losses

Which of the following is not a part of transformer installation?
a) Conservator        b) Breather c) Buchholz relay     d) Exciter

While conducting short-circuit test on a transformer the following side is short circuited,
a) High voltage side  b) Low voltage side   c) Primary side        d) Secondary side

Which winding in a transformer has more number of turns?
a) Low voltage winding b) High voltage winding
c) Primary winding d) Secondary winding

Efficiency of a power transformer is of the order of___.
a) 100 per cent        b) 98 per cent c) 50 per cent d) 25 per cent

A common method of cooling a power transformer is___
a) Natural air cooling b) Air blast cooling
c) Oil cooling d) None of these

In the transformer the function of a conservator is to__.
a) Provide fresh air for cooling the transformer
b) Supply cooling oil to transformer in time of need
c) Protect the transformer from damage when oil expends due to heating
d) None of the above

No-load current of a transformer has_
a) Has high magnitude and low power factor
b) Has high magnitude and high power factor
c) Has small magnitude and high power factor
d) Has small magnitude and low power factor

The power transformer is a constant_.
a) Voltage device     b) Current device     c) Power device       d) Main flux device

Two transformers operating in parallel will share the load depending upon their
a) Leakage reactance b) Per unit impedance
c) Efficiencies d) Ratings

In a transformer the tappings are generally provided on
a) Primary side        b) Secondary side     c) Low voltage side   d) High voltage side

The chemical used in breather for transformer should have the quality of _
a) Ionizing air b) Absorbing moisture
c) Cleansing the transformer oil d) Cooling the transformer oil

The transformer ratings are usually expressed in terms of.................
a) Volts b) Amperes c) kW d)kVA

.Material used for construction of transformer core is usually__.
a) Wood b) Copper c) Aluminium d) Silicon steel

The function of conservator in a transformer is_.
a) To project against'internal fault
b) To reduce copper as well as core losses
c) To cool the transformer oil
d) To take care of the expansion and contraction of transformer oil due to variation of
temperature of surroundings

Buchholz's relay gives warning and protection against_
a) Electrical fault inside the transformer itself
b) Electrical fault outside the transformer in outgoing feeder
c) For both outside and inside faults
d) None of the above

The value of flux involved m the e.m.f. equation of a transformer is____-
a) Average value      b) r.m.s value c) Maximum value    d) Instantaneous value

Silicon steel used in laminations mainly reduces______.
a) Hysteresis loss     b) Eddy current lossesc) Copper losses       d) All of these

Which of the following is the main advantage of an auto-transformer over a two winding
a) Hysteresis losses are reduced b) Saving in winding material
c) Copper losses are negligible d) Eddy losses are totally eliminated

Two transformers are connected in parallel. These transformers do not have equal
percentage impedance. This is likely to result in___.
a) Short-circuiting of the secondaries
b) Power factor of one of the transformers is leading while that of the other lagging
c) Transformers having higher copper losses will have negligible core losses
d) Loading of the transformers not in proportion to their kVA ratings

Open circuit test on transformers is conducted to determine
a) Hysteresis losses   b) Copper losses      c) Core losses d) Eddy current losses

Short circuit test on transformers is conducted to determine.

a) Hysteresis losses   b) Copper losses       c) Core losses d) Eddy current losses

The size of a transformer core will depend on
a) Frequency b) Area of the core
c) Flux density of the core material d) Both (a) & (b)

Which of the following parts of a transformer is visible from outstde?
a) Bushings b) Core c) Primary winding   d) Secondary winding

Auto-transformer makes effective saving on copper and copper losses, when its
transformation ratio is_______.
a) Approximately equal to one b) Less than one
c) Great than one d) None of these

Part of the transformer which is most subject to damage from overheating is _
a) Iron core b) Copper winding    c) Winding insulation d) Frame or

In a thermal power plant cooling towers are used to____
a) Condense low pressure steam
b) Cool condensed steam
c) Cool water used in condenser for condensing steam
d) Cool feed water of boiler

Advantage of hydro-electric power station is__________.
a) Low operating cost b) Free from pollution problems
c) No fuel transportation problems d) All of these

Which power plant normally operates at high speeds?
a) Diesel engine plant b) Petrol engine plant
c) Steam turbine plant
d) Hydroelectric power plant

By which of the following systems electric power may be transmitted?
a) Overhead system b) Underground system
c) Both (a) & (b) d) None of these

Overhead system can be designed for operation up to _
a) 11 kV b)33kV c)66kV d) 400 kV

Which of the following materials is not used for transmission and distribution of electrical
power? j
a) Copper b) Aluminium c) Steel d) Tungsten

Galvanised steel wire is generally used as_____.
a) Stay wire b) Earth wire
c) Structural components d) All of these

The usual spans with R.C.C. poles are___.
a) 40—50 meters     b) 60—100 meters    c) 80—100 meters    d) 300—500 meters

The operating voltage of super tension cables is up to_.
a)3.3kV b)6.6kV c)llkV" d)33kV

Which of the following methods is used for laying of underground cables?
a) Direct laying        b) Draw-in-system    c) Solid system        d) All of these

The operating voltage of extra high tension cables is upto__.
a) 6.6 kV b) 11 kV c) 33 kV d) 66 kV

High voltage transmission lines use______.
a) Suspension insulators b) Pin insulators
c) Both (a) & (b) d) None of these

High voltage transmission lines use______.
a) Suspension insulators b) Pin insulators
c) Both (a) & (b) d) None of these

Overhead lines generally use
a) Copper conductors
c) A.CS.R. conductors
b) All aluminium conductors
d)None of these

The material commonly used for sheaths of underground cables is_
a) Lead b) Rubber c) Copper d) Iron

A feeder, in a transmission system, feeds power to___.
a) Distributors b) Generating stations c) Service mains     d) All of these

Which circuit breaker is generally used in railway traction?
a) SF6 circuit breaker b) Air break circuit breaker
c) Vacuum circuit breaker d) Minimum oil circuit breaker

A relay used for protection of motors against overload is_.
a) Impedance relay b) Electromagnetic attraction type
c) Thermal relay d) Buchholz's relay

A circuit breaker will normally operate_____.
a) When the switch is put on b) When the line is to be checked
c) When the power is to be supplied d) Whenever fault in the line occurs

Which relay is used for feeders?
a) MHO relay b) Translay relay
c) Merz price protection d) Buchholz relay

Buchholz relay is operated by_.
a) Eddy current relay b) Gas pressure
c) Electro-magnetic induction d) Electro-static induction

Wireman theory sem 4 jan 2016 questions

In a power transformer the current flowing in
the coil connected to the AC source is..........
A  LT winding
B   primary winding
C  HT winding
D  secondary winding

The transformer used to transmit the power
to longer distance is called as..............
A  current transformer
B   step up transformer
C   voltage transformer
D  step down transformer _

The function of this magnetizing current (lm)
is to.......
A   magnetize the core
B  energize the primary winding
C   energize the secondary winding
D   to the compensate the loss

The magnetizing current (im) is very small in
magnitude and lags the applied voltage (Vs)
A 120°
B 90°
C 60°
D 30°

The transformation ratio (K) is more than 1
then the transformer is a........
A  step up transformer
B  auto transformer
C  step down transformer
D  current transformer

The transformation ratio (K) is more than 1
then the transformer is a........
A  step up transformer
B   auto transformer
C  step down transformer
D  current transformer

tn which condition the maximum efficiency
will occur in transformer?
A  iron loss greater than copper loss
B   iron loss equal to copper loss
C   copper loss greater than iron loss
D  copper loss less than eddy current loss

To ensure that the core insulation between
clamp plates and core bolts is adequate, the
test voltage applied is.........
A   1.0 .KV
B   1.5 KV
C  2.0 KV
D   2.5 KV

As per IE rule, in H - type pole mounted
sub -station, minimum clearance between
live conductor and earth structure is..........
A  305 mm
B  310 mm
C  315 mm
D  320 mm

The incoming and outgoing lines in a sub -
station are connected to...............
C  bus bar
D gang isolator

Bus bar assembly should be installed at a
height from the ground is........
A 2.75 m
B 2.50 m
C 2.25 m
D 2.15 m

The bus bar sections are available in
standard length of............
A 3.50 m
B 3.55 m
C 3.60 m
D  3.65 m

For bolts and nuts used for connecting
aluminium bus bar shall be........
A  tinned forged brass
B iron
C copper
D steel

Bus bar supports are spaced (maximum)
apart is..........
A 500 mm
B 550 mm
C 600 mm
D   650 mm

The temperature of cooker is controlled
A thermostat switch
B  SPT switch
C  two way switch
D   push button switch

Rod type thermostats are being used in
A  geysers cooking ranges
B  small mixers
C  room heater
D  cooling ovens

The name of mercury switch used in a power
transformer is.........
A current relay
B  bucbholz's relay
C  voltage relay
D  thermal relay

In the distribution substation the step down
voltage 3 phase, 4 wire for supply is........
A 440V
B 415V
C  410 V
D   400 V

The lightning arrestors to protect the
substation from lighting is installed on
A HTside
B  primary side
C   LT side
D   secondary side

The pole mounted sub stations are generally
used for transformer capacity upto.........
A  250 KVA
B   200 KVA
C   150 KVA
D 110KVA

The OCB is installed on the...............
A HTside
B   LT side
C   primary side
D  secondary side

As per IE rules to H - type pole mounted
sub stations, phase to phase clearance
between jumpers is..............
A  0.91 m
B   0.90 m
C   0.81 m
D   0.80 m

Pellet type lead oxide arrestor acts as an
insulator if the temperatures increased
A 130*C
B 140°C
C 145°C
D   150°C

ACB stands for..........
A  Air Circuit Breaker
B  Air Current Breaker
C  Air Case Breaker
D  Air Conductor Breaker

Transformers used to transform high voltage
and high current is...............
A  two coil transformer
B  current transformer
C   potential transformer
D   instrument transformer

Which one is the specification of potential
A  Voltage ratio
B Current
C Wattage
D impedance

EHT stands for............
A  Extra High Terminal
B   Extra High Tension
C   Extra High Thermostat
D   Equipment High Tension

Underground LT cables voltage capacity
A 1.1 KV and below
B 2.2 KV and below
C 3.0 KV and below
D   3.3 KV and below

Full form of Mi cables is..
A  Multi Insulated cables
B  Mineral Insulated cables
C  Multi Insulated conductor
D   Mini Insulated cables

In UG cable joints, the cold pouring
compound consists of a resin base and a
hardener which is...........
A  poly amino
B   poly vinyl
C  poly chloride
D poly methyl

The mixture of the compound used in UG
cable joints is resin and hardener, this is
churned till the compound colour is..........
A blue
B grey
C white
D red

The bituminous compound melting
temperature is.........
A 100eC
B 90°C
C 80°C
D 70°C

The electrolyte used in simple voltaic cell
A  dilute sulphuric acid
B  ammonium chloride
C   potassium hydroxide
D  zinc oxide

The potential difference in volts is
A emf-laRa
B emf-IR
C emf-P.D
D  PD-emf

High energy density battery used in
spacecraft is..........
A  lead acid battery
B  lithium battery
C  nickel cadmium ceils/battery
D  alkaline manganese cells/battery

The capacity of the cell/battery is expressed
A Ah
B Wh
C  W sec
D  A sec

A 20 Ah battery can supply 1A cunent
A  0.02 hr
B  0.2 hr
C  2.0 hr
D  20 hr

The Leclanche cell contains a strong solution
A ammonium chloride
B potassium hydroxide
C   manganese dioxide
D  sulphuric acid

Local action in a simple voltaic cell, are seen
from the...........
A  positive plate
B  zinc plate
C   carbon plate
D   lead plate

The plante plates in a lead acid battery are
made of...........
A  pure lead
B  lead peroxide
C   lead sulphate
D   nickel hydrate

The specific gravity of an electrolyte is
measured with a.............
A pyrometer
B hydrometer
C thermometer
D galvanometer

Which one of the following will ascertain the
condition of the lead acid battery?
A  specific gravity
B  no of plates
C  area of plates
D   distance between plates

In a fully charged lead acid battery the
specific gravity is.............
A 1.26
B 1.20
C 1.18
D 1.15

A secondary battery should not be
discharged beyond the minimum value of
voltage is...........
A 1.3 V
B 1.5V
C 1.7 V
D   1.8 V

Secondary cell temperature during charge
does not exceed the limit specified............
A 40°C
B  41 °C
C 42°C
D 43°C

In larger transformers a stepped core
arrangement is used to minimize the use of
copper and............
A  iron loss
B  eddy current loss
C  hysteresis loss
D  copper loss

Transformer lamination thickness for 50 HZ
A 0.25 mm
B 0.24 mm
C 0.23 mm
D  0.22 mm

Primary winding has 450 turns and
secondary winding has 90 turns. What will be
the secondary voltage if primary voltage is
220 volt?
A 45 volt
B 44 volt
C 42 volt
D 40 volt

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