The purpose of feedback transformer & diode in complementary commutated inverters is to-
In order to obtain static voltage equalization in series connected SCR’s connection arer made of-
In phase controlled rectification PF=
Why sector winding is used in synchronous motor?
A calculation of making current where MVA & KV was given.
The oop voltage e1 & e2 of 2 full-bridge inverters added using o/p transformer. In order to eliminate 5th harmonic from o/p voltage, the phase angle between e1&e2 will be-
A single phase fully controlled line commutated ac-dc converter operates as an inverter when-
An SCR has half cycle surge current rating of 3000A for 50Hz. One cycle surge current will be. (double of that)
When compared to an symmetrical thyristor, the turn off time & reverse blocking voltage of an asymmetrical thyristor will be-
A step-up chopper is feed from an 220v dc source to deliver a load voltage of 66o v. If the non conducting time is 100micro-sec then reqd pulse width will be. (get duty cycle only)
There were some 5-6 numerical problems which I could not remember totally but they consist of firing angle & power transfer of inverter, SCR. Go llok for that.
Relay current setting & Ct ratio was given you have to find out Relay Pick up Current.
One question from Dc shunt motor- like a resistance is added of 4.5 ohm in series with arm where rest of arm is 0.5 ohm. Machine is supplied 220v. find out the null current.
In aptitude part see through series completion there was a 5-6 no of that.
No aptitude questing like avg, %, proff-loss, prob, etc.
Why rotor of SCIM is skewed?
Good transformer oil contains how much amount of water in ppm?
Lightning over voltage create how much volt?
K/s(s+1)(s+5) then find out the value of K so that system become stable.
There was a question from definition of Nyquist criteria.
Standing done up to the frequency range of? (audio)
If a square waveform if given to the supply side of a 2wdg transformer its o/p waveform will be-
SC test done on transformer because....
If a transformer is operating in .8 PF lag & at efficiency of .9, if now P is .8 lead the efficiency will become.
Interpoles are connected for?
Dielectric strength of air?
A alternator is connected to a grid. Now its prime mover is go slow by ½. Change in its exiting current to held in synchronism.
Is the strength of capacitor in LPF is increased the op voltage will-
The voltage of a generator and an infinite bus are given 0.92, 10 deg & 1.0, 0 deg resp. the generator acts as a –
A wave will not experience any reflection when impedance of line is equal to- surge imp
Power transmitted is related to system voltage as-
Delay creator ckt name (multivibrator name actually)
In tachogenerator adjustment is done by-
Surge wave is attended by- (C,L,R)
there was 10 question related to measurement-
Read all electrostatic instrument related question from any competitive exam book.
Lowest reading in moving iron meter is-
In galvanometer damping is provided by-
In electrodynamic meter a battery & a resistance is provide for-
Megger is used for-
A question like an ac is applied against a moving coil meter it will reads-
Rectifier type instrument measures what value - (Rms)
Advantage of electrostatic instrument is-
Creeping occurs because-
Why 2 holes are drilled oppositely in disc of energy meter.
Energy meter is a _____ type equipment (recording)
There was a question related to selection of a voltmeter based on accuracy-
Advantage of hay bridge over anderson bridge-
Inductance is measured by – (all the 3 bridge name) .
Potentiometer is which type of instrument-
Which type of motor is used in refrigerator?
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Vacuum may be used for reflective insulation of liquid O2 tank
Permissible water content in transformer oil is 50 ppm
Carbon-pile resistors for insulation of oil-filled cables
Q.2.Memory of a computer can be increased by
increasing the magnetic bubble diameter
decreasing the magnetic bubble diameter
using adomax, a recent hard magnetic material
using strontium titanate (Sr Ti O3)
Q.3.The residual magnetic flux density is more in
metallic magnets
ceramic magnets
graphite
iron oxide
Q.4.Manganese ferrites is a 1:1 mixture of
MnO and CdO
MnO and Fe2O3
MnCl2 and Fe2O3
MnCl2 and CdO
Q.5.High frequency transformer cores are generally made of
Cast iron
Mumetal
Ferrite
Graphite
Q.6.For high speed reading and storing of information in a computer, the use is made of
ferrite
piezoelectric
pyroelectrics
ferromagnetics above 7680 C
Q.7.The poles of alternators are usually made of
wrought iron
permalloy
CdS
alnico
Q.8.In a semi-conductor strain gauge, the change in resistance on application of strain is mainly due to the change in its
lenght
diameter
resistivity
length and diameter
Q.9.Transformer oil is a liquid insulator and is mainly used in transformer.It is filled into transformer tank to serve the following purposes: I. To transfer the heat generated inside the transformer core and windings, to the outer cooling surfaces. II. To main insulation in the primary and secondary windings.
Only I is correct
Only II is correct
Both I and II are correct
None of these
Q.10.Electrons in an atom may be visualized by
spectroscopic techniques
radiography
optical microscope
etching techniques
Q.11.Most malleable metal is
Au
Ag
Cr
Osmium
Q.12.As the temperature of a p-type semi-conductor is gradually and continuously increased, the fermi level will move
into the valence band
into the conduction band
towards the middle of the forbidden gap
into the region between the acceptor level and the valence band
Q.13.Which one of the following polarization mechanisms/sets of mechanisms contribute to the static dielectric constant of a homo-polar neutral dielectric?
Electronic
Electronic and ionic
Electronic, ionic and dipolar
Electric and dipolar
Q.14.Consider the following materials: 1. Pure silica 2. Bakelite 3. Hard rubber 4. Paraffin The correct sequence of the DECREASING order of loss angles (60 Hz) of these dielectric materials is
1,2,3,4
1,4,3,2
4,1,2,3
4,3,1,2
Q.15.Which one of the following materials is piezoelectric?
Pb2 Au
BaTiO3
MgAl2O4
NiFe2O4
Q.16.The residual resistivity of metals
is essentially independent of temperature
increases linearly with increasing temperature
decrease linearly with increasing temperature
initially increase linearly with temperature and then remains constant
Q.17.Consider the following metals:1. Zinc2. Gold3. Silver4. CopperThe correct sequence of the increasing order of their resistivities is
4,3,1,2
3,4,2,1 (Ans)
4,3,2,1
3,4,1,2
Q.18.A type-I super-conductor maintained at a temperature T < Tc is subject to a magnetic field H < Hc. The superconductor will exhibit.
perfect diamagnetism
partial diamagnetism
perfect paramagnetism
partial paramagnetism
Q.19.The magnetic susceptibility of a paramagnetic material is
less than zero
less than one but positive
greater than one
equal to zero
Q.20.Magnetostriction is a phenomenon whereby the magnetisation of a ferromagnetic material leads to a change in
relative permeability
physical dimensions
spontaneous magnetisation
magnetic susceptibility
Q.21.Two initially identical samples A and B of pure germanium are doped with donors to concentrations of 1*1020 m-3 and 3*1020 m-3 respectively. If the hole concentration in A is 9*1012 m-3, then the hole concentration in B at the same temperature will be
3*1012 m-3
7*1012 m-3
11*1012 m-3
27*1012 m-3
Q.22.Consider the following statements :Pure germanium and pure silicon are examples of1. Direct band-gap semi-conductors2. Indirect band-gap semi-conductors3. Degenrate semi-conductorsof these statements
1 alone is correct
2 alone is correct
3 alone is correct
1 and 3 are correct
Q.23.Consider the following statements : In a semi-conductor, the measurement of Hall co-efficient provides quantitative information on1. Density of carriers2. Polarity of carriers3. Effective mass of the carriers4. Mobility of the carriersOf these statements :
1 and 2 are correct
2 and 3 are correct
1 and 3 are correct
1,2,3 and 4 are correct
Q.24.Silicon carbide reinforced aluminum metal matrix composites find application in
the manufacture of transformer cores
the manufacture of cutting tools
the manufacture of standard resistors
aerospace industry
Q.25.GaAs LEDs emit radiation in the
ultra-violet region
violet-blue-green range of the visible region
visible region
infra-red region
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