31-05-2013, 12:18 PM
Electrical Interview Question
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Electrical interview question: What is electric traction?
Answer: Traction means using the electric power for traction system i.e. for railways,
trams, trolleys etc. electric traction means use of the electricity for all these. now a
days, magnetic traction is also used for bullet trains. basically dc motors are used for
electric traction systems.
Electrical interview question:How can you start-up the 40w tube lite with 230v
AC/DC without using any choke/Coil?
Answer:It's possible by means of Electronic choke.otherwise it's not possible to ionize
the particles in tube. light, with normal voltage.
Electrical interview question:What is "pu" in electrical engineering?
Answer:Pu stands for per unit and this will be used in power system single line
diagram there it is like a huge electrical circuit with no of componenes (generators,
transformers, loads) with different ratings (in MVA and KV). To bring all the ratings
into common platform we use pu concept in which, in general largest MVA and KV
ratings of the component is considered as base values, then all other component
ratings will get back into this basis.Those values are called as pu values. (p.u=actual
value/base value).
Electrical interview question:Operation carried out in Thermal power station?
Answer:The water is obtained in the boiler and the coal is burnt so that steam is
obtained this steam is allowed to hit the turbine , the turbine which is coupled with the
generator generates the electricity
Electrical interview question:Why link is provided in neutral of an ac circuit and fuse
in phase of ac circuit?
Answer:Link is provided at a Neutral common point in the circuit from which various
connection are taken for the individual control circuit and so it is given in a link form
to withstand high Amps. But in the case of Fuse in the Phase of AC circuit it is
designed such that the fuse rating is calculated for the particular circuit (i.e load)
only.So if any malfunction happen the fuse connected in the particular control circuit
alone will blow off.
Electrical interview question: what is the diff. btwn. electronic regulator and ordinary
rheostat regulator for fans?
Answer:The difference between the electronic and ordinary regulator is that in
electronic reg. power losses are less because as we decrease the speed the electronic
reg. give the power needed for that particular speed but in case of ordinary rheostat
type reg. the power wastage is same for every speed and no power is saved.In
electronic regulator triac is employed for speed control.by varying the firing angle
speed is controlled but in rheostatic control resistance is decreased by steps to achieve
speed control.
Electrical interview question:whats is MARX CIRCUIT?
Answer:It is used with generators for charging a number of capacitor in parallel and
discharging them in series.It is used when voltage required for testing is higher than
the available.
Electrical interview question:What is encoder, how it function?
Answer:An encoder is a device used to change a signal (such as a bitstream) or data
into a code. The code may serve any of a number of purposes such as compressing
information for transmission or storage, encrypting or adding redundancies to the
input code, or translating from one code to another. This is usually done by means of
a programmed algorithm,especially if any part is digital, while most analog encoding
is done with analog circuitry.
Electrical interview question:What are the advantages of speed control using
thyristor?
Answer:Advantages :1. Fast Switching Characterstics than Mosfet, BJT, IGBT 2.
Low cost 3. Higher Accurate.
Electrical interview question:Why Human body feel Electric shock ? n in an Electric
train during running , We did nt feel any Shock ? why?
Answer:Unfortunately our body is a pretty good conductor of electricity, The golden
rule is Current takes the lowest resistant path if you have insulation to our feet as the
circuit is not complete (wearing rubber footwear which doing some repairs is
advisable as our footwear is a high resistance path not much current flows through our
body).The electric train is well insulated from its electrical system.
Electrical interview question:Which motor has high Starting Torque and Staring
current DC motor, Induction motor or Synchronous motor?
Answer:DC Series motor has high starting torque. We can not start the Induction
motor and Synchronous motors on load, but can not start the DC series motor without
load.
Electrical interview question:what is ACSR cable and where we use it?
Answer:ACSR means Aluminium conductor steel reinforced, this conductor is used in
transmission & distribution.
Electrical interview question:What is vaccum currcuit breaker.define with cause and
where be use it Device?
Answer:A breaker is normally used to break a ciruit. while breaking the circuit, the
contact terminals will be separated. At the time of seperation an air gap is formed in
between the terminals. Due to existing current flow the air in the gap is ionised and
results in the arc. various mediums are used to quench this arc in respective CB's. but
in VCB the medium is vaccum gas. since the air in the CB is having vaccum pressure
the arc formation is interrupted. VCB's can be used upto 11kv.