Answer / pawar shyamkant sitaram

It depends upon the system power frequency voltage before
the fault appearing on first pole to the volage appearing
across the heathy poles after clearing the fault. The value
of first pole to clear factor is mainly decided by the
sytem grounding & ratio of zero seq.impdence to positive
sequence impedance.

Answer / ajit

iF THE THREE PHASE FAULT NOT INVOLVING THE EARTH THE
VOLTAGE ACROSS THE CIRCUIT BREAKERPOLE. FIRST POLE CLEAR
105 TIMES THE PHASE VOLTAGE IN 3 PHASE AC CIRCUIT BREAKER
ARC EXTINTION IN THE THREE POLE IS NOT SIMULTENEOUSLY AS
CURRENT IN THREE PGASES ARE MUTUALLY 120 DEGREE OUT OF
PHASE. HENCE THE POWER FREQUENCY RECOVERY VOLTQAGE OF THREE
PHASE IN WHICH ARC GETS EXTINGUISHED FIRST IS ABOUT 105
TIMES OF PHASE VOLTAGE.FIRST POLE TO CLEARE FACTOR IS THE
RATIO OF VOLTAGE BETWEEN HEALTHY PHASE TO FAULTY PHASE TO
NORMAL PHASE VOLTAGE.

Answer / sudipt jena

Actually the voltage rise due to TRV is 1.2-1.5 times that of phase voltage.And this is happened due to the 120 degree phase shift of 3 phase current leading to interrupt of current at different instants.

How we calculate the average power factor if the one phase is lag and another one is in lead?

1 Answers   DigiTech, MCR,

---

When charging a 20 MVA , 33kV/6.6kV transformer through regulated (0-6.6 kV or 0-33 kV) source on no load , what will be the maximum current drawn by transformer from source and what sould be the source capacity.

5 Answers   TATA,

---

What is the difference between harmored cabled and unharmored cables

1 Answers  

---

what is Micrologic 6.0A advantages over Micrologic 2.0A

1 Answers  

---

sometime battery charged and then automatically charged when rectifier ON conition, is there any chances please clarify the same.

0 Answers  

---

What is the reason behind 11kv 33kv 132kv.....means multiple of 11?

6 Answers  

---

single phase 230v three phase voltage 415volt why we aren't used line voltage 690v?

7 Answers   Citec,

---

what is the different ratings of ACB/VCB/SF6 which is used at HT side

3 Answers   Hosco,

---

Why electrical engineer use Cu Strip for transformer neutral why not GI Strip? What if we use GI instead of Cu does it affects the transformer performance.

7 Answers  

---

WHAT IS THE DIFFERENCE B/W THREE POINT STARTER AND FOUR POINT STARTER

1 Answers  

---

How wire size can define in electrical wiring? What is the ratio?

0 Answers   Descon,

---

how many types of cbs?with pcific ratings?

1 Answers   Bhel,

---