k.prakashchandra


{ City } karkala
< Country > india
* Profession * rtd e.e.
User No # 54717
Total Questions Posted # 0
Total Answers Posted # 521

Total Answers Posted for My Questions # 0
Total Views for My Questions # 0

Users Marked my Answers as Correct # 1313
Users Marked my Answers as Wrong # 525
Answers / { k.prakashchandra }

Question { TVS, 6911 }

Whatis the procedure for getting Electrical (light) licence
while Iam a diploma holder in electrical Engg . I Compleated
my one yr Apprentice training & worked as a junior engineer
(ele) for 2 yr(contract basis).


Answer

As you are a diploma holder you can get supervisor's permit
directly without appearing for exam .Then for contractor's
licence you should possess certain tools, instruments and
bank solvency, as applicable to the class 0f licence s.a.
1st,2nd and 3rd.For lighting, class 3 is sufficient.You
have to apply to the Govt electrical inspectorate of your
area ,in the prescribed application forms for both

Is This Answer Correct ?    14 Yes 1 No

Question { 3537 }

How synchronous motor helps to improve PF? plz explain


Answer

A synchronous motor running on no load, draws a leading
current when over excited and hence acts like a
capacitor.Then it is called a synchronous condenser.Its
leading current partly neutralises the lagging reactive
component of the load resulting in improvement of power
factor.

Is This Answer Correct ?    15 Yes 0 No


Question { 5874 }

What are series and parallel isolators?


Answer

They are also called bypass isolators which are connected
across an equipment especially CB to bypass it for certain
operation.

Is This Answer Correct ?    5 Yes 0 No

Question { 3187 }

why the electrical insulators suspention breakdowen


Answer

Due to flash over caused by lightning and rarely due to
mechanical failure

Is This Answer Correct ?    5 Yes 0 No

Question { 4763 }

Hello sir
This is prakash from
bangalore i have a doubt why we have to
maintain DG power factor in the range
0.78 to 0.8
Perhaps i f it is increased means what
will happen in DG


Answer

Keeping pf at 0.8 lag when running in parallel means the
terminal voltage of gen is higher than the system or busbar
voltage.But it results in higher gen & field currents which
cause unwanted heating of armature and also the field.If
you keep the pf at unity or -ve,the gen does not contribute
to system stability.The generator should also share the
reactive power of the system, which is usually
lagging.Anyway pf may be maintained at 0.9 to 0.95 lag.

Is This Answer Correct ?    0 Yes 1 No

Question { 5110 }

UPS battery Back time = no.of Batteries * Ah of the Battery /
output KVA * 130 ? what is the 130 means ? can any one help?
because all are using this formula how its came 130?


Answer

Ah*voltage /1000=stored energy in Kwh = back up time in
hours * load in KW. Here instead of load, rating of
inverter is given in Kva. So with load at 65% 0f inverter
rating or at 65% of stored energy, the above formula nearly
holds good

Is This Answer Correct ?    5 Yes 3 No

Question { Adani, 7575 }

In brushless excitation system how generator field current
is measure even if the slip rings are absent?


Answer

Field current of the exciter is available for reading.The
generator field current and voltage have relationship with
this current.

Is This Answer Correct ?    5 Yes 2 No

Question { 2854 }

In three phase energymeter the spindle rotating backward
why?


Answer

At least, two current coil connections are reversed.There
are usually 8 terminals in a 3 phase EM. From left, termial
no. 1,3,5 are for main side (incoming) for the 3 phases and
2,4 and 6 are for their load side .7an8 are for neutral and
are shorted inside the meter.This reverse rotation usually
takes place when CTs are used and directions of currents
are reversed.

Is This Answer Correct ?    0 Yes 0 No

Question { Crompton Greaves, 6864 }

if a single phase 3 hp submersible pump of Crompton Greaves
is moving in reverse direction and sometimes it moves in
rigth direction ,then what may be the cause....


Answer

Faulty capacitor

Is This Answer Correct ?    15 Yes 1 No

Question { RRB, 4793 }

in a dc motor we supply current only to the armature
conductors,from where is the field winding gets excited then??


Answer

Let us not forget about permanent magnet motors which are
usually very small

Is This Answer Correct ?    2 Yes 0 No

Question { 7086 }

Is there any option to replace two Genset of capacity 125KVA
with one higher capacity for same office?


Answer

That is better

Is This Answer Correct ?    2 Yes 0 No

Question { 2523 }

why doesnt the back emf hold the speed of unloaded series motor?


Answer

As field and armature are in series, the back emf opposes
the voltage across field also, reducing the field
current ,resulting in ever increasing speed

Is This Answer Correct ?    1 Yes 0 No

Question { 3172 }

why weight is put on pulley?


Answer

As a counter weight

Is This Answer Correct ?    5 Yes 2 No

Question { 9243 }

how to select earthing wire? procedures and parameters?


Answer

Earth wire should be capable of carrying at least ,the full
load current . It can be of cu ,Al or GI.

Is This Answer Correct ?    11 Yes 4 No

Question { Blue Star, 5367 }

what is -24vDC and how can generate this -24vDC


Answer

-24 V dc means potential difference from + terminal or O
potential.If we earth the midpoint 0f 48V DC source ,then
one terminal is +24V and the other -24V with reference to 0
potential ground which gets connected to all metal bodies

Is This Answer Correct ?    13 Yes 1 No

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