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!!!

in telecom we are using neutral?

1 Answers  

---

what a function diesel generetaor turbo charger & turbo charger is more heated explain reason ?

0 Answers  

---

what is the response time of relays when a FAULT OCCURS IN A POWER SYSTEM?

2 Answers  

---

List examples of voltage source?

0 Answers  

---

How do we check transformer losses and what are the ways to minimise it.

5 Answers  

---

WHY SECONDARY OF CT SHOULD NEVER BE KEPT OPEN CIRCUITED?

7 Answers  

---

What is the difference between earthing & neutral.

2 Answers  

---

How to calculate pitch, gauge of winding wire, and No. of turns for 30HP, 3 phase, 4 poles 50Hz, 380V induction motors

0 Answers  

---

Why HT motor is connected in Star?

3 Answers   Equate,

---

How to Convert Gen KW to H.T amps ?

2 Answers  

---

I NEED RRB SYLABUS FOR JE ELECTRICAL ,PLEASE SEND TO MY E- MAIL ID joo28_eee@yahoo.co.in

0 Answers  

---

how to calculate short ckt current of trafo. ex.3-ph 3MVA trfo. 11/440, impdence voltage=7.25%

1 Answers  

---