Answer / amudhavanan

TO calculate differential current
I=/I1+I2+..../ i.e The sum of all the feeder currents
connected to the bus
incase of restraining current
I=/I1/+/I2/+..... i.e The vector sum of all the feeder
cureents

Answer / amudhavanan

let me explain you with the example of low impedance busbar
protection.

As you Differential protection is based on the Law of
Kirchhoff: in a healthy system, the sum of currents
in a node must be zero.

Let I1, I2, I3 are individual feeder currents.

Then the differential current is sum of all the currents
which result zero under external fault condition. If it
internal fault , sum of all the currents is equal to fault
current.

As you know , the operating current is the sum of
differential and restraining current.

The purpose of using restraining( Bias ) element is to
ensure the relay to operate under internal fault condition.

The restraining current is the vector sum of all the
currents. Hence the restraining element reduces the
operating current of the relay to improve its sensitivity.

Answer / neda

Amudhavanan thanks for your the best explanation

Answer / abdul rahman

hi amudhanvanan.. thanks for posting the answer.. can u give
me the definitions and an example and define briefly!!!

who is invented transforner (230v).......

2 Answers  

---

What is essential to prove safe isolation of electrical circuit?

0 Answers  

---

How to calculate the size of cables (all minium/copper) for a particular load

1 Answers   BSL, Galaxy Power System,

---

Whether amorphous core transformer is commercialized or not:Name of company making amorphous core transformer and what are different rating?

0 Answers   DAE,

---

What will happen if we on 200kvr capacitor bank(11kv in bus)If there is low load on transformer (1.5 mva 33/11 kv)

0 Answers  

---

draw waveform of capacitor or inductor in a d.c ckt(during transient) with zero resistance with it(in series or parallel)also neglect resistance of wire

2 Answers   L&T,

---

why dc series motor high speed motor

3 Answers  

---

What are the circuit models used for analysis of medium length transmission lines? Which one is superior? Support your answer.

1 Answers   UPSC,

---

What is non-minimum phase transfer function?

0 Answers  

---

which %age of corona losses increses if frequency is increased to 25%.

3 Answers   ADCET, Maihar Cement,

---

WHATIS TIME CONSTANT? WHATIS ITS SIGNIFICANCE? ILLUSTRATE THROUGH EXAMLES.

0 Answers  

---

what are tpes of insulaors& its uses

1 Answers   ABC,

---