What is pour point of transformer oil?
Typical specifications are: flash point 140 °C or greater, pour point −40 °C or lower, dielectric breakdown voltage 28 kV (RMS) or greater. To improve cooling of large power transformers, the oil-filled tank may have external radiators through which the oil circulates by natural convection.
What is the standard BDV value of transformer oil?
As per IEC, the minimum BDV of transformer oil should be 30 KV as per transformer oil BDV test standard. The transformer oil is used in the transformer for insulation as well as for cooling purpose.
What is flash point test of transformer oil?
Flash point of transformer oil is the temperature at which oil gives enough vapors to produce a flammable mixture with air. This mixture gives momentary flash on the application of flame under standard condition. Flashpoint is important because it specifies the chances of fire hazard in the transformer.
What is Megger value of motor?
A general rule-of-thumb is 10 Megohm or more.
| Insulation resistance value | Insulation level |
|---|---|
| 2 Megohm or less | Bad |
| 2-5 Megohm | Critical |
| 5-10 Megohm | Abnormal |
| 10-50 Megohm | Good |
How is Megger value calculated?
Example-1: For 11KV, Three Phase Motor. IR Value =0.415+1=1.41 MΩ but as per IEEE43 It should be 5 MΩ….IR Value of Motor as per NETA ATS 2007. Section 7.15.1.
| Motor Name Plate (V) | Test Voltage | Min IR Value |
|---|---|---|
| 600V | 1000V DC | 100MΩ |
| 1000V | 1000V DC | 100MΩ |
| 2500V | 1000V DC | 500MΩ |
What is OTI and WTI in transformer?
The WTI means winding temperature Indicator and OTI means Oil Temperature Indicator which indicates the winding temperature & oil temperature of the transformer and operates the alarm, trip, and cooler control contacts. This instrument operates on the principle of thermal imaging and it is not an actual measurement.
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