prasad


{ City } new delhi
< Country > india
* Profession * asst.manager
User No # 43930
Total Questions Posted # 1
Total Answers Posted # 11

Total Answers Posted for My Questions # 3
Total Views for My Questions # 13122

Users Marked my Answers as Correct # 80
Users Marked my Answers as Wrong # 47
Questions / { prasad }
Questions Answers Category Views Company eMail

How can we calculate earth mat conductor size ..? & give the formula to determine earth conductor size?

 3 Electrical Engineering 13122



Answers / { prasad }

Question { APPSC, 14722 }

how to test vector goup of Dy11 transformer


Answer

HV side Delta,LV side Star
1) Connect HVside with 3 phase supply,
2) Short with a cable HV R phase & LV r-phase,
3) LV left open circuited
4) Now Switch on the 3-phase supply
5) Now Measure the following Voltage's
VRY,VYB,VRB
VRN,VYN,VBN
Vry,Vyb,Vrb
VRr,VRy,VRb
VYr,VYy,VYb
VBr,VBy,VBb
6)CHECK the following condition(These are derived from
Phasor diagram)
i) VBb ii)VYb=VYy
iii)VRY=VRn+VYn
iv)VYb If these all conditions are satisfied then U'r transformer
is OK

ALL THE BEST------Prasad

Is This Answer Correct ?    10 Yes 7 No

Question { NTPC, 27051 }

Why we didn’t feel electric shock in an electric train ??


Answer

because railway track acts as a earth conductor-return path

Is This Answer Correct ?    33 Yes 13 No


Question { Bhel, 7949 }

why there is a high voltage line in multiplication of 11?i.e.-
-66kv,11,kv,22kv


Answer

because form factor is the ratio of rms value to the avg
value.normally for AC current we will consider RMS VALUES
ONLY,because of this we will get 11kv,22kv,33kv...etc

Is This Answer Correct ?    1 Yes 5 No

Question { 7968 }

21. What is the purpose of taking Capacitance and Tan Delta
Test in
Transformer bushing?
22. What are the protections to be used for Generator?
23. Draw the vector diagram and condition for the
following: 1) Dyn1
2) Ynd0 3) YnYn0
24. What happens when the polarity changes in CT? Explain
briefly?
25. Explain the Term in CT Name Plate – Class: 5P10


Answer

Tan DELTA TEST TO FIND THE Dielectric losses

Is This Answer Correct ?    5 Yes 4 No

Question { TCS, 9313 }

i am swathi, b.tech 4th year.
In smps(switched mode power supply)we are using
diodes,mosfets,igbts for controling of current.
And my question is why we did not use thyristors(scr)? it
is also act as a switch,then what is the drawback of scr as
compared to above transisters> if we use the scr,then what
is happening ? plz give reply as soon as possible bcoz i
am doing project on smps. plz frnds i want ans for
that. if anybody know the ans plz send to my e-mail
id /swathi.tadakapally@gmail.com/


Answer

Hi dear this is prasad from clp (power)...we can use
thyristor(scr) but for scr we have to design firing angle
circuit separatly,we have to check whether scr is
triggering or turning on exatctly as per our requirements
or not and for high power applications it is better to
diodes,mosfet,igbts..in these we wont face firing angle
circuit design problems...bocz for the SCR firing circuit
is the heart hope so....

Is This Answer Correct ?    10 Yes 6 No

Question { L&T, 9645 }

what is the uses of C.V.T transformer in switch yard?


Answer

For measurement of high voltages in 400 kv substations as
well as carrier communication

Is This Answer Correct ?    12 Yes 3 No

Question { 4930 }

what is main reason for grid earthing for any industry


Answer

simple answer machine safety as well as man human safety....

Is This Answer Correct ?    3 Yes 2 No

Question { 5801 }

What is the fundamental cause of transients in power system?


Answer

simple answer..Machine safety & Human safety under all
cinditions

Is This Answer Correct ?    0 Yes 4 No

Question { 13122 }

How can we calculate earth mat conductor size ..? & give
the formula to determine earth conductor size?


Answer

for bolted joints cross section Area of the conductr
A=0.0013*I*sqrt(t),
for welded joints cross section Area of the conductr
A=0.011*I*sqrt(t),

I - Fault current (KA) = Fault MVA/ (sqrt3 * system KV)
t - Duration of time

Is This Answer Correct ?    3 Yes 0 No

Question { 6003 }

How transformer neutralshould earthed ? Transformer neutral
connected to earth mat in substations, right or wrong ?


Answer

Transformer is connected to nutral with a strip separatley
and this neutral is conected ground seprately

Is This Answer Correct ?    3 Yes 1 No

Question { 5031 }

what do you mean by linear and bilateral network?


Answer

Liear element: Response is directly propotional to
Excitation
Bilateral Element: what ever the direction of the currrent
response must be same

Is This Answer Correct ?    0 Yes 2 No