Table of Contents
- 1 What is dielectric strength of oil used in transformer and circuit breaker?
- 2 Which of the standard is applicable for determining the dielectric strength of transformer oil under application of power frequency voltage?
- 3 Is standard for BDV of transformer oil?
- 4 How do you test dielectric strength?
- 5 How is dielectric strength of transformer oil tested?
- 6 What is the dielectric strength of an oil transformer?
- 7 What is the breakdown voltage of cleanclean transformer oil?
- 8 How to vacuum dry transformer oil?
What is dielectric strength of oil used in transformer and circuit breaker?
Function and properties 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.
Which of the standard is applicable for determining the dielectric strength of transformer oil under application of power frequency voltage?
Factors to Test: Dielectric breakdown voltage (ASTM D877) Liquid power factor (ASTM D924-08) Interfacial tension (ASTM D971) Specific resistance (ASTM D1169)
What should be the BDV of transformer oil?
A typical value of BDV Test result for 220 / 6.6 kV Transformer oil is 65 kV and moisture content should be less than 10 ppm. BDV is an important and popular test of transformer oil, as it is the primary indicator of the health of oil and it can be easily carried out at the site.
Is standard for BDV 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. The different insulating materials have different dielectric strength.
How do you test dielectric strength?
Dielectric strength is calculated by dividing the breakdown voltage by the thickness of the sample. The data is expressed in Volts/mil. The location of the failure is also recorded.
What is standard dielectric strength of oil in kV?
It is confirmed that the dielectric breakdown voltage of pure transformer oil is about 10 kV with a gap distance of 1 mm between electrodes.
How is dielectric strength of transformer oil tested?
To determine dielectric strength, transformer oil is periodically tested by means of an oil punching apparatus. To test the oil sample, transformer oil is poured into a porcelain vessel in which two “disk electrodes,” one of 8mm diameter and one of 25mm diameter, are mounted.
What is the dielectric strength of an oil transformer?
The dielectric stength implies withstand value i.e. the electrical stress which oil can withstand safely. In practice, what is monitored in transformer is breakdown voltage (BDV) i.e. the electrical stress where oil breaks down. For power transformers, minimum BDV can be taken as 50kv for 2.5mm gap.
How to check the quality of transformer oil?
1 Transformer Oil Dielectric Strength Test Procedure. The gap of the electrodes is first checked with a gauge. 2 Moisture Test of Transformer Oil. The presence of moisture in a transformer is very harmful. 3 Neutralization Test of Transformer Oil. Acids are formed in a transformer during operation. 4 Filtration of Transformer Oil.
What is the breakdown voltage of cleanclean transformer oil?
Clean transformer oil generally contains no water and other impurities, which allows it to have sufficient breakdown voltage (over 60 kV). This parameter is determined by using flat copper electrodes with rounded edges, 2.5 mm apart. The breakdown process is also greatly influenced by dissolved gases.
How to vacuum dry transformer oil?
There are three ways/stages of vacuum drying of transformer oil: breakdown voltage changes only slightly and stops at the level of 60 kV. At this stage, the removal of dissolved and bound water is performed; slow increase in breakdown voltage due to the removal of bound water.