1.
Multi-layer helical windings are commonly
used in the transformers as high voltage windings
for 110 kV and above
2.
_______is a negatively charged particle
present in an atom.
Electron
In a synchronous motor, damper windings are
provided on ________?
stator frame.
We can apply source transformation to
voltage source when a resistance is connected to it in
14 HP.
To eliminate 5th harmonic in the induced
voltage phase breadth should be ??
72°
________is universally used for windings of
electrical machines because it is easily workable without any possibility of
fracture.
Copper
In a paper mill where constant speed is
required
individual drive is preferred
When the rotor speed, in a synchronous
machine, becomes more than the synchronous speed during hunting, the damper
bars develop ??
induction motor torque.
In induction heating ______
The resistance of charge must be low
and voltage applied must be high in order to produce sufficient heat.
Which of the following is the voltage for
single phase A.C. system ?
240 V
The resistivity of water should not be less
than
2000 Q m
The speed of a superfast train is
more than 100 kmph
For 25 kV single phase system power supply
frequency is
50 Hz
Which of the following insulating materials
was suitable for low temperature applications ?
Diatomaceous earth
In DC machine torque depends on which of the
following?
Both armature current (I) and flux
(f)
The steam engine provided on steam
locomotives is
single acting non-condensing type
Maximum power developed by a synchronous
motor depends on ___?
supply voltage and excitation
The thickness of metallic shielding on
cables is usually
0.04 mm
A 3 layer, total diameter of an ACSR
conductor is 5 cm. Find the diameter of each strand?
1 cm
If a step function is applied to the input
of a system and the output remains below a certain level for all the time, the
system is
not necessarily stable
For a particular material the Hall
coefficient was found to be zero. The material is
metal
To reduce the radio interference which line
is/are transposed?
Either power and telecommunication
lines
Which of the following quantities are to be
calculated for generator bus?
Q and d
________electromagnets generally function as
holding magnets.
Portative
For a 3-phase, 4 pole, 50 Hz synchronous
motor the frequency, pole number and the frequency are halved. The motor speed
will be??
1500 rpm
In the cables, the location of fault is
usually found out by comparing
the capacitances of insulated
conductors
Which of the following materials is the best
conductor of electricity ?
Copper
The photo-electric effect occurs only when
the incident light has more than a certain critical
frequency
To measure a resistance with the help of a
potentiometer it is
not necessary to standardise the
potentiometer
Suri transmission is
hydro-mechanical
In case of type-1 system steady state
acceleration is
infinity
The filament of an electric bulb is made of
tungsten
The conductivity of a metal is determined by
the electronic concentration and the
mobility of the free electrons
Due to which of the following factors the
brush wear rate is altered ?
all of these
A cable carrying alternating current has
hysteresis and leakage losses only
Which of the following motor is suitable for
frequent starting and stoppings?
capacitor start motor
PVC stands for
polyvinyl chloride
The temperature, under thermal and
electrical system analogy, is considered analogous to
voltage
For a standard frequency the machine
operates at a particular speed known as
synchronous speed
In a system low friction co-efficient facilitates
reduced velocity lag error
Which of the following is a semiconductor
material ?
Silicon
Multiple inlet system of air cooling of
turbo-alternators can be used for machines of rating upto
60 MW
Full form of VVVF control _______?
variable voltage variable
frequency.
The usual values of maximum flux densities
for distribution transformers using hot rolled silicon steel are
1.1 to 1.35 Wb/m^2
Co-efficient of adhesion reduces due to the
presence of which of the following ?
both dew on rails and oil on the rails
The illumination at a point 5 meters below a
lamp in 6 lux. The candle power of the lamp is ___?
150.
Out of the following
which is an insulating material ?
Paper
Which of the following methods does not take
into account the maximum temperature rise under variable load conditions ?
Method of average losses
The type 2 system has _____ at the origin.
two poles
Which of the following should be done to
make an unstable system stable ?
The gain of the system should be
increased
In transmission lines distribution constants
are _____?
resistance , inductance and
capacitance
Besides a constant
speed a synchronous rotor possesses which of the following advantages ?
High power factor
Which of the following are integrating
instruments ?
Ampere-hour and watt-hour
meters
Cross magnetization effects which of the
following?
commutation
In a circuit a 33 Q resistor carries a
current of 2 A. The voltage across the resistor is
66 v
An insulated metal sphere of 20 cm diameter
is charged by rubbing with charges 2 × 10-8 C. Potential developed will be
_____?
1800 V.
Commutator in DC generator is used for
________?
convert AC armature current in to
DC
Due to proximity effect, the increase in
conductor resistance is not negligible in _____
underground cable
Induction heating process is based on which
of the following principles ?
Electro-magnetic induction
principle
Super conductivity can be destroyed by
application of magnetic field
The material of the heating element for a
furnace should have
high specific resistance
To measure an A. C. voltage by using an A.C.
potentiometer, it is desirable that the supply for the potentiometer in taken
from the same source as the unknown
voltage
In D.C. machines the number of slots per
pole usually lies
between 9 to 16
A 3 stack stepper motor has 12 teeth on
stator as well as on rotor. Determine the step size when each stack excited?
10 degree
Ohm's law is not applicable to
vacuum tubes
In a domestic cake baking oven the
temperature is controlled by
series-parallel operation
The S.I. unit of power is
watt
The impurity atoms is semiconductors
reduce the energy gap
________is an open loop control system.
Field controlled D.C. motor
In pneumatic control systems the control
valve used as final control element converts
pressure signal to position change
In a stable control system backlash can
cause which of the following ?
Low-level oscillations
Specified quantities of load bus are
__________
P and Q
A Weston frequency meter is
moving iron instrument
Wattmeter cannot be designed on the
principle of
moving iron instrument
The property of a conductor due to which it
passes current is called
conductance
In a superconductor the value of critical
density depends upon
both magnetic field strength and
temperature
The electric flux is given D = (2y2 + z) Ix
+ 4xy Iy + x 1z C/m2. The volume charge density at point (-1,0,3) is
- 4 C/m3.
The number of passanger coaches that can be
attached to a diesel engine locomotive on broad gauge is usually restricted to
10
Current velocity through a copper conductor
is
of the order of a few ^.s/m
Maximum power developed in a cylindrical
synchronous machine depends on
synchronous reactance and
excitation
The output of a feedback control system must
be a function of
reference and output
An instrument which detects electric current
is known as
galvanometer
Properly of low temperature co-eflficient of
heating element is desired due to which of the following reasons ?
Both to avoid initial rush of
current and to avoid change in kW rating with temperature
______ is an example of piezoelectric
material.
Quartz
A universal RLC bridge uses
Maxwell Wein bridge for measurement
of inductance and modified De Santy's bridge for measurement of capacitance
A network containing
100 buses in which 10 are the voltage control buses, 5 are fixed shunt
capacitor buses, 20 are the reactive power support buses, 6 are the generator
buses. Find the size of the Jacobian matrix?
163×163
The basic elements of a electric drive are
electrical motor and control
system.
Which of the following is essentially needed
while selecting a motor ?
Starter
By the use of which of the following, high
frequency power supply for induction furnaces can be obtained ?
Motor-generator set
_______ motor is a constant speed motor.
Synchronous motor
Advantages of shunt compensation is/are
_____?
It requires less maintanance
A moving iron instrument can be used for
both D.C. and A.C.
Which of the following statements is not
necessarily correct for open control system ?
Presence of non-linearities causes
malfunctioning
The breakdown of insulation of the cable can
be avoided economically by the use of
both inter-sheaths and insulating
materials with different dielectric constants
If the excitation is reduced, the power
factor is _______?
leading power factor
The simplest and most commony used methode
for temperature control is ______
Transformer tappings.
In electrical-pneumatic system analogy the
current is considered analogous to
air flow rate
Rotor of a motor is usually supported on
_______ bearings.
ball or roller
