Answer / kanchan dogra

Selection of HT cable is based on
1. short circuit calculation
2. Full load current capacity
1. Short Ckt. calculation
if total load is 3000 KVA, V 11 KV
short ckt MVA on HV side = 350 MVA (As per standard practice)
short ckt. current Ik= MVA/root3 x KV
350/root3 x 1= 18.4 KA
duration of short Ckt= 1 Second
cross section area of the conductor = Ik x root T/.094
18.4x root T/.094 = 95 SQ.mm

2. Full Load current
Total Load= 3000 KVA
System Voltage= 11 KV
Full load current = KVA/ root3 x KV
3000/root 3 x 11= 157 Amp.
derating factor = .7
current carrying capacity after derating = 157/.7 = 224.95 AMP.
Hence select cable for this current.

Pleasd Tell Me..... In Generating Stations Why The Generation Of ELECTRICITY Is In 3 Phase Form?? OR In Generating Station Why We Generates The ELECTRICITY In The 3 Phase?? Why Not In The 4 Phase, 5 Phase Or 6 Phase Form??

3 Answers  

---

Why we are mention U1, V1, and W1 in primary side of transformer give technical reason

1 Answers  

---

What are eddy current and define rms value?

4 Answers   NTPC,

---

which cable is used for 15 Hp monoblock pump 3phase and service wire Distance is 210 feet please tell me cable size Armaured

0 Answers  

---

What is an exciter and how does it work?

7 Answers   FCUK, Lotte Chemical Titan, TATA,

---

HOW TO CALCULATE HV CABLE SIZING?

0 Answers   KNPC, L&T,

---

If a transformer primary winding operates at 240v, the secondary at 120v and the load is 1500w & the transformer is rated at 92% efficient, what's the current flowing through the primary winding of the transformer? What is the formula for finding this?

0 Answers  

---

What is the mechanism of WTI

0 Answers   JBS,

---

What is the effect on power factor, shown by a trivector meter; incase of reverse phase sequence. If the power factor of a system is lag what meter will show in case of reverse phase sequence connected to the meter. and What in case of lead.

0 Answers   TATA,

---

could mail me the question papers for the test.

1 Answers   ONGC,

---

how to calculate overall efficiency of diesel generator set? give us a formula with an example.

2 Answers  

---

how to detect the presence of underground cable(while digging road)etc. -give the name of instrument

7 Answers   NTPC,

---