W/M S 3

Wireman theory sem 3 july 2015 questions

When a magnet is suspended it points
directly towards....................
A south
B north
C west
D east

Which one is NOT a magnetic material?
A iron
B nickel
C cobalt
D brass

The direction of magnetic Sines around the
current carrying conductor can be found by
A Fleming right hand rule
B Fleming left hand rule
C Lenz's law
D Faradays law of electromagnetic induction

Silicon steel contains.....
A   steel with 3% of silicon
8   steel with 2.8% of silicon
C  steel with 2.6% of silicon
D  stee! with 2.4% of silicon

Generator converts the mechanical energy
into.........
A electrical energy
B solar energy
C  chemical energy
D wind energy

The spirt ring in a generator is made up of
A iron
B steel
C hard drawn copper
D nickel

The shunt field of DC Generator will have
A zero resistance
B medium resistance
C low resistance
D high resistance

The residual magnetism is available in
A armature winding
B shunt field
C commutator
D pole shoe tip

In the generator the excitation voltage will
be of low voltage as.............
A 24 V
B 20 V
C 18V
D   15 V

Which type of source i? NOT used for
separate excitation?
A  storage battery
B solar
C D.C.generator
D  rectified DC

The armature core laminated sheet steel disc
thickness is...................
A 0.3 mm
B 0.4 mm
C 0.5 mm
D  0.6 mm

The commutator segments are insulated
from each other by thin layers of...........
A paper
B mica
C empire cloth
D  millinex paper

The no load characteristic curve drawn
between..........................
A   field current Vs induced voltage
B  armature current Vs induced voltage
C  field current Vs armature current
D   armature current Vs terminal voltage

Which one of the following is NOT an
advantage of separately excited generator?
A Terminal voltage remains stable
B  Drop in the armature will not affect the field
flux
C   Can be used where a wide range of terminal
voltages is required
D   Inconvenience of providing a separate DC
source for excitation

Which one of the following will not improve
the insulation resistance of the motor?
A  Blowing hot air through the machine
B Cleaning the brushes
C   Heating with carbon filament lamp
D  Varnishing the winding

The armature torque of the DC series motor
is directly proportional to......................
A armature current
B  supply voltage
C speed
D efficiency

The two point starter is frequently used
with......
A  DC shunt motors
B  DC series motor
C  DC shunt compound motor
D  DC long compound motor

The value of form factor is
A 1.11
B 1.00
C 0.707
D 0.637

In an inductance circuit current lags the
applied voltage by..................
A 90°
B 120'
C 180°
D 270°

The inductive reactance XL is
A 2rL
B 2nfL
C 2irf
D  2fL

An inductive circuit connected to a 280V,
Z=5.12 ohms current is.................
A 39.0A
B   39.1 A
C 39.2A
D 39.3A

Formula of P.F. cosB is........
A true power / apparent power
B apparent power / true power
C apparent power - true power
D  apparent power + true power

The phase sequence indicator consists of 3
terminals are.................
A R.Y.B
B Y,R,B
C U.V.W
D V,U,W

The non salient pole type rotor speed range
is from.......
A 1000-1500 rpm
B 1000-2000 rpm
C 1000-2500 rpm
D  1000-3000 rpm


The three phase armature windings are
electrically apart by an angle of
A 90°
B 120°
C 180°
D 270°

Alternators are usually
A KW
B KVAR
C KVA
D KV

Which one is NOT a type of single phasing
preventers?
A Mechanical
B  Current sensing
C . Voltage sensing
D  Resistor sensing

Which rule /iaw is applied to find the direction
of magnetic field of the rotor?
A  Fleming's right hand rule
B  Maxwel's cork screw rule
C  Lenz's law
D  Faradays law of electro magnet induction

The insulation resistance of an electric motor
may be in the range of.................
A  10 to 90 megohms
B   10 to 100 megohms
C  10 to 110 megohms
D  10 to 120 megohms

D.O.L starters are used to start the AC motor
only upto...............
A 2 HP
B 3 HP
C 4 HP
D   5 HP

The colour of dry silica gel
A green
B pink
C blue
D red

In transformer winding, pnase displacement
at 1° clock position is.....................
A +30°
B -30°
C +60°
D -60°

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