| Customization: | Available |
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| Warranty: | 1 Year for Insulating Oil Bdv Tester Transformer |
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For measuring BDV of transformer oil, portable BDV measuring kit is generally available at site. In this kit, oil is kept in a pot in which one pair of electrodes are fixed with a gap of 2.5 mm (in some kit it 4mm) between them. Now slowly rising voltage is applied between the electrodes. The rate of rising voltage is controlled at 2 KV/s and observe the voltage at which sparking starts between the electrodes. That means at which voltage dielectric strength of transformer oil between the electrodes has been broken down.
This measurement is taken 3 to 6 times in the same sample of oil, and we take the average value of these readings. 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.
Dry and clean oil gives BDV results, better than the oil with moisture content and other conducting impurities. Minimum breakdown voltage of transformer oil or dielectric strength of transformer oil at which this oil can safely be used in transformer, is considered as 30 KV.
Dielectric dissipation factor is also known as loss factor or tan delta of transformer oil. When a insulating materials is placed between live part and grounded part of an electrical equipment, leakage current will flow. As an insulating material is dielectric in nature the current through the insulation ideally leads the voltage by 90o. Here voltage means the instantaneous voltage between live part and ground of the equipment. But in reality, no insulating materials are perfect dielectric in nature.Hence current through the insulator will lead the voltage with an angle little bit shorter than 90o. Tangent of the angle by which it is short of 90o is called dielectric dissipation factor or simply tan delta of transformer oil. More plainly, the leakage current through insulation does have two component one capacitive or reactive, and another one is resistive or active. Again it is clear from the above diagram, the value of ′δ′ which is also known as loss angle.
If the loss angle is small, then the resistive component of the current IR is small which indicates a high resistive property of the insulating material. High resistive insulation is a good insulator. Hence it is desirable to have loss angle as small as possible. So we should try to keep the value of tanδ as small as possible. The high value of this tanδ is an indication of the presence of contaminants in transformer oil.
Hence there is a clear relationship between tanδ and resistivity of insulating oil. If the resistivity of the insulating oil gets decreased, the value of tan-delta increases and vice verse. So both resistivity test and tan delta test of transformer oil are generally not required for the same piece of the insulator or insulating oil.
In one sentence it can be said that tanδ is a measure of the imperfection of dielectric nature of insulation materials like oil.
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