Answer / jaswinder

% impedence is use to determine the max fault current the
transformer is capable of delivering to a downstream short
circuit.
Fault current=FLC*100/%imp.
this fault current is use to cal fault MVA
Fault MVA = 1.732 x fault current x V.

eg: If transformer of 2000kVA,5%imp having flc of around
1200A is use to supply to a motor of same flc carrying
capacity and if the voltage drop at transformer terminal is
more than the permissible voltage drop (+- 10%)during
stating of motor then the above transformer will be of
lower rating hence we have to select the transformer rating
higher than 2000kVA eg:-3000kVA (In other words transformer
having higher SC current capability ).If voltage remain
within the rated voltage of the motor then no oversizing of
tranformer is required.

Answer / akr

hieght of winding effect on impedane

draw a dol with the following rtds,stop/start,ct,vt and o/l supply is 6.6kv and the coil is 110v

1 Answers   Anglo Eastern,

---

if the HR asked to me., you have got 92% in higher secondary but got only 72% in engg whats the reason??what should i have to say ..please help me..

8 Answers   Honeywell, Wipro,

---

Q2). When 3 dice are simultaneously thrown, which of the following would be obtained? (a) Result 1: “A 5, a 3 and a 6” (b) Result 2:” A 5 three times” (c) Result 3:”A 5 twice and a 3” (d) All three results are equally likely. (Musigma Question)

2 Answers   Mu Sigma,

---

Auto transformer starter gives the same effect as star/delta strater if its turn ratio = A 0.5 B 0.67 C o.66 D 0.577

1 Answers  

---

In supply RYB are mentioned. But in transformers, why they are mentioning XYZ?

3 Answers  

---

which type of cabel

0 Answers   DMRC,

---

What are the symptoms of a bad PG card of a drive (inverter) esp. of Yaskawa Ac Drives (inverters) G7 ?

0 Answers  

---

Can an inverter be used as a converter? How?

0 Answers  

---

what is the disaddvantages of high power factor

2 Answers  

---

what is efficient motors and how it is different from normal induction motors

0 Answers   Sarthak Contracts,

---

Why we use RYB phase sequence?

3 Answers  

---

I have a drawing of a wound rotor induction motor for a crane. This crane motor has 5 forward speeds & 5 reverse speed implemented of course with different amount of resistance for each speed setting selected. What has got me scratching around is the fact that 8 of the 10 speed selections switch in uneven (unbalanced) amounts of resistances on each of the 3 connections to the motor's rotor.Can this be possible? I would have assumed this would produce unbalanced rotor currents and therefore vibration in the motor. I would greatly appreciate anyone's comments on this. Many thanks, Confused.

0 Answers  

---