Answer Posted / chintan patel

It can be different for DC , 1phase AC , 3 phase AC , systems,

Lets calculate for all ,

1 ) For DC ( you have not mentioned Voltage but considering 230 V )

100 kw means 100000 watt

formula for DC power p= vi

100000= 230xi

i=100000/230= 434 amp

we always use current rating of the mccb is 1.5 times of full load current so we can use 434x1.5= 652 amp.
( if system is not running on full load select 630 Amp MCCB, if its on full load select 800A )


2 ) For 1phase AC,

Power: P = V I cos phi ( cos phi is power factor is not known assume 0.8 )

100000 W = 230 x I x 0.8
I = 543 Amp

we always use current rating of the mccb is 1.5 times of
full load current.
mccb required 543 Amp X 1.5 = 815 Amp
select 800 Amp MCCB

3)

If load is 3 phase AC ,

Power P = sqrt(3) x V x I x cos phi

100000 w = 1.73 x 415 x I x 0.8
I = 174

we always use current rating of the mccb is 1.5 times of
full load current.
mccb required 174 Amp X 1.5 = 261 Amp

( if system is not running on full load select 250 Amp MCCB,
if its on full load select 315 A )

why occ characteristics curve in not tracing back when we are bringing back the rhoestat?

1860

---

earth also having a gravitational force (magnetic field of north and south)but it attracts any object compare to this theartifical magnetic cant perform same as earth why?

1960

---

What is the difference between single core 2 wire and single core 3 wire system? Which application we are using this? and for What purpose we are using this?

2333

---

surge tank, hrc fuse, earthing transformer, firm power objective type

1621

---

What is vaccum currcuit breaker.define with cause and where be use it device?

1111

---

i have applied for the post of RRB section engineering chennai board please send me previou papers and solved answer. my mail id jagarapusrinivas@gmail.com

1963

---

i have interview in Pepsi company what type of question will ask please send the question and answeer

3441

---

How to calculate the phase to phase clearness of HT /// LT bus bar?????

2072

---

What is the end effect of linear induction motor ??

2018

---

What is mean by Sensitive Earth fault & what are the effects

4516

---

A cotter joint is generally used to transmit

1240

---

does any one know where we can purchase insulation oil for high voltage oil filled cables

2326

---

PLEASE TELL ME ABOUT QUESTION PAPER OF UPCL ENTERENCE EXAM.

7944

---

What is the capacitance values of 132,220,400 & 765 kV current transformer

1909

---

What is transister define the transister ammiter ,base, colector.

2212

---