Answer / vinod

NGR capacity should allow the mininmum earth fault current
so that system with minimum earth fault current can be
detected and isolated by earthfault relay.
ie NGR fuction is to reduce the earth fault to the minimum
level in the range of earth fault relay

Answer / raghavendran.r

As far I know the formula is Rngr = Vln/Ig.

where Ig is the current flowing through the Neutral Grounding resistor(let through fault current), which depends upon the type of system you haver chosen, i.e High impedance grounding or Low resistance earthing.

The let through ground fault current through the neutral is low for High resistance earthing and its High for low resistance earthing.

But the important condition is that the let through fault current should be greater than the system capacitive charging current to avoid transient over voltage.

WHY EXCITATION OF SYNCHRONOUS MACHINE IS DC NOT AC

8 Answers   NTPC,

---

primary of transformer connected to Dc supply in series with switch, and secondary connected on ammeter, what happens when swith On and OFF. (or) if continuously On and OFF

9 Answers  

---

What is the kva?

2 Answers   Makino Auto, SAL Steel Power, Sapphire Group,

---

what is the meaning of WYE and DELTA in Electric meter?

0 Answers  

---

What is the use of IGBT in UPS & its working??????????

5 Answers   Reliance,

---

How to calculate earth wire load by formula

0 Answers   Caparo,

---

When to use Oil Transformer type and When to use Dry type? What is the difference between both?

2 Answers   ABC,

---

What is the diff btw Conventional & Addressable Fire Alarm System???

5 Answers   Emerson,

---

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

11 Answers   ABB,

---

how to select the automotive wire size by mathematical calculation. for xenon headlamp with ballast. the ballast given data voltage 10-17v,current permenant 6amp, run up phase is 15amp, peak at swicth on max 400micro sec is 40amp.the sum of cable resistance is 150mohm.please provide referenc document if any for relating the peak at switch on current,time & wire wire size

0 Answers   Tyco,

---

How to calculate load requirement of a 50 flat apartment with 5 kw each unit,sizing of cable,transformer

1 Answers  

---

Is it weather conditions make any problems to the electrical equipments and if yes means is it any precautions needed?

1 Answers   Hexaware,

---