Answer / bandarawy

The normal bias setting in a differential relay is 20%.
So, complete earth fault protection is not possible with
differential relay. That is why you need a seperate earth
fault relay with sensitive settings like 5%.

Why we not use the impedance relay in protection of short transmission line ?

4 Answers  

---

When oil level in the oltc of power transformer reduces , oil surge relay will act or not

4 Answers  

---

why neutral grounding transformer is used for generator and why it is not used for transformers?

1 Answers   UPCL,

---

Minimum IR value of 1.1 kv grade 3.5c (300, 240,185,150,120,95,70,50,35,25) sqmm Aluminium XLPE cable and 4c (16, 10,6 & 4) sqmm cu arm cable between RY,YB,BR,RN,YN,BN,RE,YE,BE & NE.

0 Answers   Gasco,

---

Initially motor starts with star connection ,after few timing changes to delta connection, why the motor should run continously in star connection,it gives high torque & low current?

3 Answers  

---

how many methods for starting an induction motor?

7 Answers   Hindustan Unilever Limited, Hyundai, TPL,

---

what is the advantage of connecting capacitors in delta than in star?

1 Answers   NTPC,

---

We have drive feeding an output contactor for a 5000 hp motor @ 5kV application. The motor FLA is 629amps x 1.25% service factor = 786.25 amps The cable that we current have in place between the drive and the output contactor is 350kcmil- MV-105 (parallel cables). Per the NEC table 310.60 (C) (69). This show the cable ampacity is at 615 amps per cable for a rating of 1230 amps. We have derated the cable for the cable tray and the multiple cables application and our calculations show that after the correction factor factor we are at 922amps. 1230 amps x .75% correction factor factor = 922.5 amps. The customer is driving us to then use another safety factor of .25% off of the already derated cable. Can you please provide a longhand calculation for your solution on this application?

0 Answers   Siemens,

---

What are the site acceptance tests for power cables, DG Sets, LT panels & 30kVA UPS ?

0 Answers  

---

Why we use 2core cable for Dc motor.Can I use 3core?

5 Answers   JK Paper, Maharaja Whiteline,

---

Why is shaft current insulation required on large motors & when should it be checked i.e. before or after assembly?

2 Answers   Aramco,

---

how to calculate the tarriff for an industry whose kva demand is 10 mva

0 Answers  

---