Answer / s naved masood

For Transformers lesser than 1000KVA
1. Overcurrent protection at HT(fuses or overcurrent relays)
2. Overcurrent protection at LT (LT Air circuit breaker)
3. Moisture protection (Breather with silica gel)
4. Overburden protection (Temperature gauge)
5. surge protection (surge arrestors)
6. Pressure relieve valves
For transformers equal to or above 1 MVA
1. Overcurrent (IDMT and High set char relays)
2. surge protection (surge arrestors)
3. Oil temperature indicators (alarm + trip)
4. Winding temp indicators (alarm + trip)
5. Oil surge relay
6. Pressure relieve valves
7. sudden pressure relays
8. differential Protection
9. Restricted earth fault protection
10. Overfluxing protection
11. Buchholz relay (alarm + trip)
Also there are various tests that are done as a part of preventive maintenence.
1. winding resistance
2. turns ratio
3. Tan delta
4. Dissolved gas analysis
5. Furon analysis
6. Sweep frequency responce analysis
7. Partial discharge
8. Magnetic balance
10. Megger testing

Answer / soms

for small Xmers(transformers)we use simple protective
devices i.e. fuses,for medium size we use overcurrent
relays, for large size Xmers we use differential protection
scheme recommended .

Answer / virendra

OT, WT, Bucholz

how electronic energy meter works?

12 Answers  

---

what is diffrence between dc motor and dc generator?

3 Answers   HBL Power Systems,

---

What is the ideal position cooling fan inside the dc motor?

0 Answers   Kay Bouvet,

---

Hi, I've just got into my electrical engineering course and I need some help with a question of mine here. During a site visit, we were shown a main LT panel which has switchgears, ammeters and different kinds of relays and the distribution network from that panel. In the main LT panel I've noted down the current readings as Ir - 163A, Iy - 150A and Ib - 147A. The Line to Line voltage is 415 V at 50 Hz and Line to Neutral voltage is 230V at 50 Hz. From the above details, how would I calculate the kVA rating of transformer? The primary side voltage of the transformer is 11 kV and the secondary side voltage is 415V and the frequency is 50 Hz.

2 Answers  

---

give types of Air conditioners commonly used &its use?

5 Answers  

---

what will be the effect if we increase the excitation of a alternator??

3 Answers  

---

what is the difference b/w conductor and semicoductor

1 Answers  

---

Is CBCT protect human life? If yes than how?

1 Answers   Torrent Power,

---

I want to know in body earthing which material can be use either copper plate or GI plate please guide us which is best option.

3 Answers  

---

Give the topology of current amplifier with current shunt feedback?

0 Answers  

---

why the efficiency of the dc machine is high ,when it is operated as a generator?

3 Answers  

---

explain the operating principles of CVT & RVT

2 Answers  

---