Question { Crompton Greaves, 35911 }

What is the diff. between two phase & three phase supply.

Answer

in the 3 phase system no need separate neutral wire because
phase to phase have 120 deg phase shift,so by the cycle one
phase alternatively act as neutral.

Mr . vinoth babu please explain the above statment .

Question { HP, 25152 }

what is maximum demand.

Answer

This is the maximum power Continuously consumed by the
consumer.

Question { ABB, 13926 }

if we convert kw into Ampers,which one formula use by
us,pls tell me?

Answer

two method we are using

1. KW/ ROOT 3 X P.F X ( applied voltage/ 1000 )

2.(KW X 1000) /ROOT 3 X P.F X applied voltage

Question { BEL, 420472 }

I want formula to calculate cable size as per load given in
kw & amp.I searched many sites but didn't right answer.Plz
reply me asap.

Answer

Hai
First u will convert the KW OR kvA loads to AMph
After u can select the suitable cable from cable manufuture
catalouge . that u will consider derating factor = 0.72
For Example
50 A
16 SQ XLPE Al cable may be suitable
The 16 sqmm cable suitable for 70A ( DATA TAKEN FROM
HAVEELS CATALOUGE)
70 * 0.72 = 50.4 A
So the cable suitable for the above load.
after u will cross check voltage drop for the cable

Question { BEL, 420472 }

I want formula to calculate cable size as per load given in
kw & amp.I searched many sites but didn't right answer.Plz
reply me asap.

Answer

Hai
The formula is delda v =
rt3 x I X Z X L/ 1000 x no OF runs
% OF VOLTAGE DROPS = Deta v
------ X 100
APPLIED VOLTAGE
The % of voltage voltage drops should be below 3 %
I = Requird current
Z = Cable impedance
L = cABLE LENGTH

First how many Amp you required
Example - 80
then you go to cable catalouge find out suitable cable
size
then calculate original current carring capacity of that
cable and multifly with 0.72 ( derating factor )
example in catalouge may be 35 sq mm cable and current
carring capacity may be 125 A
125 X 0.72 = 90
The carring carring capacity point of view this cable will
be ok
next you will check voltage drop with help of above said
fomula

Question { 4286 }

In a company has been installed an analog amperemeter, this
company was suplied by generator X, there is no problem in
the ampere meter, rigth now this company's supplied by
generator Y then the pointer in amperemeter vibrating. What
happened? Why?
Thank's

Answer

first check x and y same rating d.g if u say yes then check
ct details .and also check any sound varation in your d.g
set

Question { Engineers India, 18360 }

for 1000kva transformer how kvar rating is need for this
PFI plant. and how does it will calculate? and Apmpere
rating of main cable connection?

Answer

you CAN CALCULATE based on the TENTATIVE Method

100KVA TRANSFORMER / 3 = 300 TO 350 Kvar APFC u can
selected .

Question { JSW, 186285 }

what is the difference between LT and HT power supply?

Answer

the downstream distribution is LT supply
before downstream supply is MV ( MEDIUM VOLTAGE)
Before MV Distribution is HV (HIGH VOLTAGE )

Question { Bajaj, 193531 }

How can CALCULAT the current carrying capacity of aluminum
and cOpper cables respective of that Sq.mm ? with
formulas ?

Answer

Generall we are consider for Cu 1.5A 1.6 A / SQ MM
and AL 0.8A/ sQ MM

Question { Tivoli Grand, 133930 }

What is RTCC panel and why it is required

Answer

Dear V.Senthil
your statment is correct but the OLTC provide on HT side
only .

Question { 14951 }

how can alculate the apfc panel rating?

Answer

simple method
the apfcr panel reating willbe 1/ 3 of transformer rating
Ex ample
1600 kVA -T/F
1600/3 = 533= 500 OR 550 KVAr you may be recommended

Question { 12741 }

How will you calaculate the Ct ratio based on connected
load 500KVA,and 11KV supply ?

Answer

first u shouls convert to A
500 / (root 3 x 11 )= 26.2A
So u can select 50/1A CT FOR THE ABOVE LOAD

Question { 10368 }

Can without battery on line UPS,off line UPS or Invertor
works please brief.

Answer

yes mr . Ram statment is correct . This system is working
in Nokia compus- chennai

Question { 11648 }

what is meant by unity power factor?unity means one why dont
call 2,3,4......?

Answer

Power factor = consumed power ( Kw )/ Apparent power (KVA )

SO IT IS NOT POSSIBLE TO 2,3.4

Question { 6792 }

what current is taken from a double wound 500kva transformer

Answer

hai


DATA
Tr rating = 500 kva
voltage rating = 415 v

Calculation

500 / rt 3 x .415 0r

500 x 1000 / rt 3 x415 = 695 A

i hope now u are clear