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

What is the difference between ohmic resistance and effective resistance?

2 Answers  

---

What is a feedback in control system?

0 Answers  

---

why overcurrent fault occurs in power system.

1 Answers  

---

can we identify the direction of power flow in transmission line by after only looking the tower

7 Answers   TNEB Tamil Nadu Electricity Board,

---

how to calculate neutral current in three phase four wire system

1 Answers   Auto Meters,

---

What kind of battries are generaly used with Disel Generator?

1 Answers   Exide,

---

What should be the Sandwitch type Al. bus bar capacity for 2 M.W.Gen. set, having continuous full load current- 3463 Amps,ambient temp.- 50 Deg. C., Required temp. raise-20 deg.C., it will run 24 hrs, 365 days on full load, required highly reliable.

0 Answers  

---

Why current transformer is earthed??

2 Answers  

---

why do we connect droop ct{in gensets}in y_phase only

2 Answers  

---

what is the difference between UPS and INVERTER?

5 Answers   Techno Engineering,

---

i want to know is it possible to generate usefull power by coupling generator with motor & supply gives to motor by battery source then generator generates power. remove the battery source given to the motor & feed the supply from some of the generated power supply to the motor & motor runs continously. generator generate power contnously.is it possible ?

5 Answers   UltraTech,

---

The coulomb is a unit of:(a) Energy(b) Voltage(c) Power(d) Quantity of electricity

1 Answers  

---