Answer / tapas

* In REF scheme 4 nos of CTs are used. 3 for phase and 1 for Neutral.
* It operates in the principle of balance current between phase and neutral and only inside In-zones. i.e. it protects Transformer, Busduct, LV switchgear.
* In this protection phase CTs are connected in such a way that it forms a close path between phase CT secondaries and this close path is connected with neutral CT secondary.
* In between the close path connected to common terminals of phase CT secondary and Neutral CT secondary REF relay is connected.
* When a phase fault occurs there is also residual current in Neutral. So current between both paths oppose each other and hence there will be no current in REF relay. So it won't operate.

redundant connection in contactor?

0 Answers   Emerson,

---

What is a soft start?

1 Answers   Focus,

---

What is hipot test procedure?

0 Answers   CCC,

---

On Which Pressure PRV is operated.

0 Answers   AEPL,

---

we need a ntpc previous papers

0 Answers  

---

what are the advantage and dis-advantage of 3 phase 4 wire energy meter?

0 Answers  

---

Can we install and run MCCB suitable for 440v 3Phase 4wire system, on a 220V 3Phase 4Wire System.

3 Answers  

---

how can get electrical "c" licence.i am complited in DEEE.PASSING YEAR OF 2010 I AM WORKING IN SPENCER PLAZA ELECTRICAL MAINTENANCE ,I AM DIPLOMA COMPLEATED IN ANDHRA PRADESH AND WORKING OF TN PLEASE HELP ME

1 Answers  

---

The loads are connected with phase and ground then why current flow as the loads ?

0 Answers  

---

why ten delta testing is carried out on power transformer

0 Answers  

---

Our Company's Contract Demand is 110 kVA. We use 12 Capacitors each of 12.5 kVAr Capacity to maintain Power Factor of 0.99. So, what steps should we take so that our Contract demand does not exceed 110 kVA?

1 Answers   Jindal,

---

i have interview in Pepsi company what type of question will ask please send the question and answeer

0 Answers   Pepsi,

---