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!!!

Why we cant store an ac power. If we coo store in which device we can?

0 Answers   Jindal,

---

In a power conditoining unit (inverter) of a solar plant when we measure the d.c. current fed by different strings of solar plates to inverter, the current in the negative wire is less almost by 1 ampere to the current in its positive wire say current in positive wire 5 A , then current in negative wire of the same string is 4 A. Since the current entering should be equal to current leaving then why the current is noticably less in negative wire.

0 Answers  

---

In CT,which terminal(s1,s2) need to be grounded?

2 Answers  

---

What about electrical Units. discrive in detail

0 Answers  

---

What is meant by vector group

0 Answers   GPSC Gujarat Public Service Commission, VA Tech Wabag,

---

---

how we calculate the 30 KW 3phase electric motor current on noload

23 Answers   Monnet, Siemens, SSR, Supermac Industries,

---

why we measure ouput of transformers in kva.

1 Answers  

---

How can we increase the capacity of exixting capacitor bank??????????????? PLS. Help

1 Answers  

---

OHMS Law is only applicable for ac or dc or both circuiT?.

6 Answers  

---

Genreally distribution transformers are having Star/delta connections to provide phase and neutral to the consumers. Is the neutral of the star conncted secondary grounded in these transformers?

1 Answers  

---

what is stepping motor and where can use in electrical installation.

3 Answers  

---

what happens when power factor leads or lags to electical or home appliances

2 Answers  

---