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Company >> ELECTRICAL >> ELECTRICAL Questions
 
 Bhel placement papers  Bhel Placement Papers (1)  HCL technical test questions  HCL Technical Test Questions (10)  ABB interview questions  ABB Interview Questions (46)
 
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Question   11 kv line me tino phase takra jaye to present time me approximately voltage aur current kya hoga... Rank Answer Posted By  
 Interview Question Submitted By :: Ram Sahu
I also faced this Question!!   © ALL Interview .com
Answer
It is a case of short circuit, in short circuit voltage 
drops to zero & current becomes infinite, this high current 
sences by protective relay and circuit trips.
 
0 Shahid
 
 
Answer
Its a symmetrical fault when 3phase line are connect each
other at that time its voltage is zero and current go at
infinite level which can be trip by relay. if relay are not
present it will effect the system equipment and load.
 
0 Abhishek Goyal
 
 
Question   What is Procedure the procedure to select CT's & PT's in 66kV and above substation? Rank Answer Posted By  
 Interview Question Submitted By :: Chandu
I also faced this Question!!   © ALL Interview .com
Answer
Current Transformers (CTís) and Potential Transformers
(PTís) are suitable located for supply to metering and
indicating instruments and relay circuits. CTís are
connected at the terminals of each circuit breaker and PTís
are connected right on the point where the line is terminated.
 
0 Chandu
 
 
 
Answer
above is correct but the ct is current transformer for
measuring current and pt is measuring voltage in
sub-stations.these are using in HT sub stations only 1100v
and above.
 
0 Rambabu
 
 
Answer
For example u have 100MVA transformer 66KV line 
your CT ration 100,000,000/1.7320x66,000=874.77  
so you can used CT ration 1000/1A
 
0 Kbonn
 
 
Question   Dear sir/mam please send the last 5 years {JUNIOR ENGINEER - ELECTICAL, ELECTRONICS RRB chennai } TECHNICAL, General Knowledge,and Aptitude question papers to my mail id sasikrishnasamy.15@gmail.com Rank Answer Posted By  
 Interview Question Submitted By :: Sasikrishnasamy.15
I also faced this Question!!   © ALL Interview .com
Answer
Dear sir/mam  please send the last 5 years {JUNIOR ENGINEER
- ELECTICAL, ELECTRONICS RRB chennai } TECHNICAL, General
Knowledge,and Aptitude question papers  to my mail id
 sathiya_too@yahoo.co.in
 
0 Sathiyanathan.k
 
 
Question   What are types of losses in the Transmisson Lines ? Rank Answer Posted By  
 Interview Question Submitted By :: Veer19ravi
I also faced this Question!!   © ALL Interview .com
Answer
most common loss is  I square r loss are in the transmission
loss line
 
0 Kundan Malani
 
 
Answer
There are generally two types of losses occur-1)I square R 
loss.(including skin effect) 2)loss due to corona
 
0 Pankaj Narayan Patro
 
 
Answer
TWO TYPES OF LOSSES:
1. TECHNICAL LOSSES.
2. COMMERCIAL LOSSES.
 
0 Monish
 
 
Answer
cu loss,iron loss
 
0 Bharath
 
 
Question   WAHAT IS ELECTRICITY Rank Answer Posted By  
 Interview Question Submitted By :: Raj
I also faced this Question!!   © ALL Interview .com
Answer
FLOW OF ELECTRONS INA CONDUCTOR AGAINST A RESISTANCE
 
0 Balaji
 
 
Answer
the energy of electron (-)& proton(+) its Call ELECTRICITY
 
0 Brijesh
 
 
Answer
It is a form of energy. Used for doing work.
eg:- fan,light etc
 
0 Tushar
 
 
Answer
a flow of free electrons in a conductor  from the source end
to other end
 
0 Sreenu
 
 
Answer
FLOW OF ELECTRONS INA CONDUCTOR AGAINST A RESISTANCE
 
0 Moni
 
 
Question   how much cuurrent flow through human body effected ???? Rank Answer Posted By  
 Interview Question Submitted By :: Yanamadala Ashok
I also faced this Question!!   © ALL Interview .com
Answer
12ma
 
0 N.gopala Krishna
 
 
Answer
as per IEEE-80 for a human being of weight 70kg can survive 
a current of 116ma for 1sec.
 
0 Ahamar
 
 
Answer
Actually currents below 5ma are not dangerous.But between 
10ma and 20ma the current is dangerous becoz the victim 
loses muscular control.

   u can also get practical experience .take 5ma 
shock !!!!!  u can verify it.
   or 
 u can verify from book by V.K Mehta ,principal of power 
system
 
0 Ruddho
 
 
Answer
its 25-30mA
 
0 S.karthik
 
 
Answer
its 9mA,that why we us elcb in home of 5 mA so that it get 
tripped.
 
0 Arvind
 
 
Answer
above 9mA cane cause sensation to human body
 
0 Deepak Mishra
 
 
Question   I have seen 1 video in which a person getting shock while standing at top of a train,i have 1 question? why the people sitting in the train doesn't get shock while that man getting shock from top of the train? How the earthing of train works? Rank Answer Posted By  
 Interview Question Submitted By :: Deepak
I also faced this Question!!   © ALL Interview .com
Answer
ya i also saw that video ,one thing have u watched that 
person touch the electrical line so only he got shock(what 
i saw).

If suppose u saw another video means ,high voltage lines 
have the capability to ionise the upto certain 
distance ,the person may went near the ionise area so he 
got the shock
 
0 Sathish Charles
 
 
Answer
I think that man was ionised and stucked with the line and
there will be no touch with train or it can be a false video
 
0 Parveen Sharma
 
 
Answer
all are wrong
the train power line ,ie positive is the main supply (over
head lines 22KV DC) and it collected by bow or pentagon
collector and the track is the negative or earth, in thius
principle train is working.
 
0 Rafi
 
 
Answer
Agreed with your suggestion but in that particular video the
men is working as a short circuit media between + and -.than
howit is possible the other people were safe as many person
got touched with the outer metal part with the train.
 
0 Parveen Sharma
 
 
Answer
all the above answers are wrong since the frequency of the 
Over head line (above the train) is 25 Hz and it is Ac 
supply,  if it is DC supply as in answer 3 how long it will 
be supplied since DC supply cannot be supplied for a long 
distances,  since there will be voltage drops.  you can 
notice the substaions along with the railway lines,  for DC 
supplies there will not any substations, only generating 
stations will be there.  

Traction motors will be establised in the locomotive is DC 
sereis motor, now you may ask about the supply since it is 
AC supply with 25KV with 25Hz frequency the Rectifiers will 
be used in the locomotive.

ANSWER 3 is correct in only tram way service that to with 
24Volts DC supply.

now coming to why man was not elctrocuted in that video:

since it low frequency the field around conductor will less 
and until unless he touches the line/conductor he will not 
get effected.  then about passengers before them when the 
person was electrocuted the nearest substation to the 
accident area will trip, that area will be isolated with in 
Micro seconds. hence passengers will not get effected.
 
0 Subrahmanyam
 
 
Answer
VIDEO MAY BE WRONG OR IT MAY BE DUE TO INDUCTION EFFECT
 
0 Salma
 
 
Answer
I am also saw that video. he touch the pastive line and 
negative line also so his got the shock.

the train power line ,ie positive is the main supply (over
head lines 22KV DC) and it collected by bow or pentagon
collector and the track is the negative or earth, in thius
principle train is working.
 
0 Sivabalan.j
 
 
Answer
train boby earth works for passangers and the man who is 
standing on the train touch directly the conductor and the 
voltage pass though his body so he died
 
0 Veeranna Gowda
 
 
Answer
current will flow only when there is a difference in 
potential(voltage difference),persn touches the wire is 
between ground(zero potential) and the line (line 
voltage ,usually 25000 volts ) . where as people in train 
are at same potential(or as train body made of metal which 
is good conductor bypasses all current) so no current and 
no shock.
 
0 Shashidara Reddy
 
 
Answer
NO 9 Ans is excatly correct and all above are wrong because 

the supply will pass through the shortest route the return

path and train body itself is the return path to the supply 

the voltage is 25,000 V AC Supply the taken to train by 

panthogragh and then converted in DC variable 900V to 0

by vairing the voltage only the speed can be varried.

if any quries reply chsubhash@yahoo.com
 
0 Subashkumar
 
 
Answer
I agree with answer 3, but there is also one more thing
between 
+ve and -ve that is disc insulators which increases the
resistance between +ve and -ve line. so passengers dont get
shock
 
0 Vijay
 
 
Answer
Dear all plese let you know that it is not a dc supply it 

is AC supply.
 
0 Subash
 
 
Answer
hi frnds...
first of all the charge inside any metal body is zero.
(.remember ur basic class lessons.)so when the man touch 
the +ve line while the train is in gorund potential
(0 voltage) current starts flowing through his body,.

one more ex hav u ever seen a  crow sittin on a single line 
got eletricuted???? you could never see coz it is same 
potential and there is no current flow through its body...
i hope u understand :)
 
0 John
 
 
Answer
THE RIGHT AND PERFECT ANSWER IS HERE..   WE KNOW THAT 
CURENT FLOW THROUGH OUTSIDE OF THE TRAIN TO GROUND(LESS 
RESISTENSE PATH),25000V TO 0V.SO PEOPLE SITTING IN THE 
TRAIN DOESNOT GET SHOCK WHILE OTHERE MAN GETTING SHOCK FROM 
TOP OF THE TRAIN.
 
0 Prashant
 
 
Answer
HI guys........
    
       this is srinivas in my point of u 

1.in train peopele sit inside the train doesn't get shocked
 bec current comes in supply line (2500v) and return path is
ground if u touch neutral directly nouthing will happend.
this true.....

2.when man siting in top of the train touch the line
directly and stay in top of the train it will shocked bec
the current will flow to the earth through that person bec
circuit will closed.....
thats sall..
3.i was explain in 1 answer 

       in my point of view this is current if their is any
successions please tel me to my email.
 
0 K.s.s.srinivas
 
 
Answer
The exact answer is 

The rails are earthed at certain points which act as
neutral. Now the train which is on the rails is also at neutral.

A person touching neutral alone doesnt get electrocuted
(passengers inside train). 

Person touching neutral as well as overhead line will get
severely electrocuted, so is the case of the person standing
on the train touching the HT overhead line.

As soon as the man touches the line heavy current starts
flowing through his body produces enough heat to burn his
body alive, even though the neutral tends to be at zero
potential which makes the passengers inside or outside
touching the train safe.

Hope this makes good sense..
 
0 Kannan
 
 
Answer
answer 10 is absolutely wrong ...
 
0 Ans 10 Dickhead
 
 
Question   how much capacity(rating) of generator required to operate a load of 100kv. Rank Answer Posted By  
 Interview Question Submitted By :: Sumit Verma
I also faced this Question!!   © ALL Interview .com
Answer
125 kva
 
0 Ankush Miglani 09718151073
 
 
Answer
125 KVA
 
0 Mohammad Farman Khan-abu Dhabi
 
 
Answer
how can u say that dude...the question i beleive is
wrong....load is expressed in watts not in volts.
 
0 S.karthik
 
 
Answer
can i 've the answer briefly
 
0 Vinay
 
 
Answer
rating purely depends on load not on vltg.
 
0 Shashidara Reddy
 
 
Answer
rating depends on wattage rating and not on volts. also if 
it is 100 kw then if its power factor is assumed to be 0.8 
then to supply that load ganerator rating should be 
100/.8=125
 
0 Abhishek Jha
 
 
Question   if the supply voltage increased by N times, the x-section of conductor will be......... Rank Answer Posted By  
 Interview Question Submitted By :: Praveen_201k
I also faced this Question!!   © ALL Interview .com
Answer
x-section is not decided by voltage
 
0 K.prakashchandra
 
 
Answer
X-sectional area depends only on current ,not voltage
 
0 K.prakashchandra
 
 
Question   anyone please send me the BHEL Written test papers....NEED IT Rank Answer Posted By  
 Interview Question Submitted By :: Amol
I also faced this Question!!   © ALL Interview .com
Answer
plz send me the papers n my mail ID
 
1 Amol
 
 
Answer
nine
 
0 Anandakummar
 
 
Answer
hI SEND ME BHEL WRIITEN TEST SAMPLE FOR ELECTRONICS .. 
PLEASE URGENT
 
0 Mallika
 
 
Answer
Dear sir,

please sent the bhel exam paper for iti written test paper 
electrical with anser papel 2008,2007,2009,
 
0 Electrical
 
 
Answer
plz send me d BHEL sample n 2010 papers of ELECTRONICS........
 
0 Dushyanth
 
 
Question   What is the calculating formula for HT and LT amps in a transformer. Rank Answer Posted By  
 Interview Question Submitted By :: Kudipudibhanuprakash
I also faced this Question!!   © ALL Interview .com
Answer
P=root3 v i cospie

I = P/root 3 . v. cos pi
 
0 Lokesh Ranjith
 
 
Answer
the rating KVA=Root 3*Vl*Il  Apply primary and secondary
voltages to get the max. current
 
4 Baskaran.r
[VRVS]
 
 
Answer
V*I(HT SIDE)=V*I(LT SIDE)
 
0 Mukul Tyagi
[VRVS]
 
 
Answer
FOR EXP....

in 50mva trx mean
       P= ROOT3 *V*I*COS
       
     50*1000*1000=1.732*110*1000*I
      
        I=  262.4 IN PRIMARY SIDE
 
     50*1000*1000=1.732*33*1000*I
        
        I=  874.8 AMPS  IN SEC SIDE
 
0 Thyagarajan
[VRVS]
 
 
Answer
CURRENT IN LT SIDE
         =KVA *1000/1.732*LT VOLTAGE*COSQ


CURRENT IN HT SIDE
           = KVA *1000/1.732*HT VOLTAGE*COSQ
 
3 Rajesh Tewari
[VRVS]
 
 
Answer
amps in LT side I=P/root 3 * v* cos pie                    
amps in HT side I=P/root 3 * v* cos pie
 
0 Balasubramanian
[VRVS]
 
 
Answer
If the current of one side either primary or secondary is
known than the current of other side will be in same 
proportion as the volotage ratio of primary and secondary 
side.
For example -for a 1000 KVA 11kv/0.4 kv transformer if there
is 1 amp. current in HT side than current in LT side will be
 1x11x1000/400 i.e almost 26 amps.
 
0 S.l.bhatt
[VRVS]
 
 
Answer
I=HTV/LTV
 
0 Manoj Kumar
[VRVS]
 
 
Answer
KVA= VI/1000
 
0 Awadhesh Kumar
[VRVS]
 
 
Answer
Let suppose u have taken 1500 kva transformer of  11kv to 415 v u wanna be the current calculation for the both HT side and LT side. But u also think that u have connect load of the transformer 1000 kw.  In this case both HT & LT SIDE power drawn is same. But this is three phase so we take formula
P equal to SQ ROOT 3 *V* I COS phai
Remember cos phai is necessary becuse of we know KVA :::: KW/ COS phai
U have connect 1000kw and its drawn full lo
ad then it wil be calculate in HT SIDE
1000*1000:::1.732*11000*0.8* I(u take power factor as0.8)
I::::65.6A
WHILE calculating in LT SIDE IT wil be
1000*1000::: 1.732*440*0.8* I
I:::1739.05A
because power drawn HT & LT SIDE depend on load connected to the transformer
 
0 Raju Kumar Singh
[VRVS]
 
 
Answer
I-kva/root3vi 
cos ph. (both 
side)
 
0 Deepak
[VRVS]
 
 
Answer
I=KVA/ROOT3VI COSPEI
 
0 Yakub Reddy
[VRVS]
 
 
Question   what is impedance of transformer? Rank Answer Posted By  
 Interview Question Submitted By :: Sriniplusvasan
I also faced this Question!!   © ALL Interview .com
Answer
The percentage impedance of a transformer is the volt drop 
on full load due to the winding resistance and leakage 
reactance expressed as a percentage of the rated voltage.
 
2 Thowsif_emerson_csm Team
 
 
Answer
impedance is total resistance offered by the circuit & in
transformer there is a leakage flux due to windings in air
expressed as leakage reactance and resistance drop in
windings so the vector addition gives impedance.
 
1 Akash
 
 
Answer
Well friends--- % impedance is defined as the ratio of
impedance voltage(the voltage at rated frquency applied to
one winding and other winding kept short circuit to flow
full rated current in circuit) to the rated voltage of the
transformer... Correct if i m wron g.
 
0 Rated Kuldeep
 
 
Answer
hi kuldeep you saying ratio between impedence voltage to 
rated voltage...... is this really correct ah ??????
impedence is the ratio of voltage to current is it?????can 
you explain me abt this?????????
 
0 J.vinothkarthick
 
 
Answer
The percentage impedance of a transformer is the volt drop 
on full load due to the winding resistance and leakage 
reactance expressed as a percentage of the rated voltage.
  
The Impedance(between primary Secondary) of the Ideal 
Transformer is Infinity.As there is no current conduction 
path b/w primary and secondary as the energy conversion is 
beacuse of induction only.I.e.,Current Between Primary and 
secondary is Zero and Impaedance is Infinity..


It is th question iam faced in My interview.

Hope this may useful for you.
 
0 Mahesh-lanco
 
 
Answer
Percentage Impedance (Z%)
 

The impedance of a transformer is marked on most 
nameplates -  but what is it and what does the Z% figure 
mean?

Definition
The percentage impedance of a transformer is the volt drop 
on full load due to the winding resistance and leakage 
reactance expressed as a percentage of the rated voltage.

It is also the percentage of the normal terminal voltage 
required to circulate full-load current under short circuit 
conditions  

Measuring Impedance
The impedance is measured by means of a short circuit 
test.  With one winding shorted, a voltage at the rated 
frequency is applied to the other winding sufficient to 
circulate full load current - see below:
 



The percentage impedance can then be calculated as follows:

Z%  =  Impedance Voltage   x  100
Rated Voltage

 

Changing the Impedance Value
The most economical arrangement of core and windings leads 
to a 'natural' value of impedance determined by the leakage 
flux.  The leakage flux is a function of winding ampere 
turns and the area and length of the leakage flux path.  
These can be varied at the design stage by changing the 
volts per turn and the geometric relationship of the 
windings.

The Effect of Higher and Lower Impedances
The impedance of a transformer has a major effect on system 
fault levels.  It determines the maximum value of current 
that will flow under fault conditions.

It is easy to calculate the maximum current that a 
transformer can deliver under symmetrical fault 
conditions.  By way of example, consider a 2 MVA 
transformer with an impedance of 5%.  The maximum fault 
level available on the secondary side is:

                    2 MVA x 100/5 = 40 MVA 

and from this figure the equivalent primary and secondary 
fault currents can be calculated.

A transformer with a lower impedance will lead to a higher 
fault level (and vice versa)

The figure calculated above is a maximum.  In practice, the 
actual fault level will be reduced by the source impedance, 
the impedance of cables and overhead lines between the 
transformer and the fault, and the fault impedance itself.

As well as fault level considerations, the impedance value 
also:

 determines the volt drop that occurs under load - known 
as 'regulation' 
 affects load sharing when two or more transformers operate 
in parallel 

Sequence Impedance (Z1  Z2  Z0)
The calculation above deals with a balanced 3-phase fault.  
Non-symmetrical faults (phase-earth, phase-phase etc) lead 
to more complex calculations requiring the application 
symmetrical component theory.  This in turn involves the 
use of positive, negative and zero sequence impedances 
(Z1,  Z2 and  Z0 respectively).

As with all passive plant, the positive and negative 
sequence impedances (Z1 and  Z2) of a transformer are 
identical.

However, the zero sequence impedance is dependent upon the 
path available for the flow of zero sequence current and 
the balancing ampere turns available within the 
transformer.  Generally, zero sequence current requires a 
delta winding, or a star connection with the star point 
earthed.  Any impedance in the connection between the star 
point and earth increases the overall zero sequence 
impedance.  This has the effect of reducing the zero 
sequence current and is a feature that is frequently put to 
practical use in a distribution network to control the 
magnitude of current that will flow under earth fault 
conditions.

regards 
dhruv shah 
G.T.P.L
 
5 Montu
 
 
Answer
Impedance of transformer (Z), is the total opposition that 
a circuit presents to alternating current
 
0 Aizaz Khan
 
 
Question   What is FM200 Fire Supresion System?? Rank Answer Posted By  
 Interview Question Submitted By :: Thowsif_emerson_csm Team
I also faced this Question!!   © ALL Interview .com
Answer
The FM-200 Fire Suppression System is an engineered system 
utilizing
a fixed nozzle agent distribution network. The system is 
designed
and installed in accordance with the National Fire 
Protection
Association (NFPA) Standard 2001, ďClean Agent Fire 
Extinguishing
Systems.Ē When properly designed, the FM-200 system will 
suppress
surface burning fire in Class A, B, and C hazards.
 
0 Suhana_t
 
 
Answer
FM 200 is fire supresion system which is used to neutralise 
the fire in closed areas.Normaly it is used in Data Centre, 
server room or very critical areas of facility due to its 
cost.
FM200 is name of Gas.When it is mechnically dressed  
with  ,Cyilender, nozzel,connecting pipes,support &pressure 
switch called FM200 system.and mainly used in very critical 
area of facility like-Servsr room,data Center ,and for very 
imporant set up due to gas cost.
Funtion: when ther will be fire the gas releases on closed 
area FM200 gas is having capability to minimize the absence 
of Oxygen &as we know absence of oxygen fire can not take 
place.
 
0 Ramendra Shukla
 
 
Answer
Heat absorption is the main  extinguishing property of FM 200 system and oxygen replacement is secondary.
 
0 Sandeep.sekharan@yahoo.com
 
 
 
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