Electrical Interview questions
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 day, 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 components (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 achievespeed
control.
Electrical interview question: How tube light circuit
is connected and how it works?
Answer:A choke is connected in one end of the tube light
and a starter is in series with the circuit. When supply is provided ,the
starter will interrupt the supply cycle of AC. Due to the sudden change of
supply the chock will generate around 1000volts . This volt will capable of to
break the electrons inside the tube to make electron flow. once the current
passes through the tube the starter circuit will be out of part. now there is
no change of supply causes choke voltage normalized and act as minimize the
current.
Electrical interview question: what 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 controlusing 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:what is the principle of
motor?
Answer:Whenever a current carrying conductor is placed in a
stationary magnetic field it produce turning or twisting movemnt is called as torque.
Electrical interview question:why, when birds sit on
transmission lines or current wires doesn't get shock?
Answer:Its true that if birds touch the
single one line (phase or neutral) they don't get electrical shock... if
birds touch 2 lines than the circuit is closed and they get electrical shock..
so if a human touch single one line(phase) then he doesn't get shock if he is
in the air (not touching - standing on the ground if he is standing on the
ground then touching the line (phase) he will get a shock because the ground on
what we standing is like line (ground bed - like neutral)। and in the most of electric lines
the neutral is grounded..so that means that human who touch the line closes the
circuit between phase and neutral.
Electrical interview question:what is meant by armature
reaction?
Answer:The effect of armature flu to main flux is called
armature reaction. The armature flux may support main flux or opposes main
flux.
Electrical interview question:what happen if we give 220 volts
dc supply to d bulb r tube light?
Answer:Bulbs [devices] for AC are designed to operate such
that it offers high impedance to AC supply. Normally they have low resistance.
When DC supply is applied, due to low resistance, the current through lamp
would be so high that it may damage the bulb element.
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.
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