The GTD1001D Insulating oil breakdown voltage tester adopts a completely new electromagnetic compatibility (EMC) concept, designed to prevent tester crashes during testing and to ensure stable operation even in high magnetic fields.
The GTD1001D also uses advanced voltage breakdown control technology, which keeps the breakdown energy at a very low level, preventing contamination of the oil sample during testing and ensuring that the test results are accurate and reliable.
A unique advantage of this tester is its built-in electronic boost system. The voltage regulation power supply utilizes an electronic inverter sine wave generator, providing accurate voltage output with high waveform quality. It is unaffected by grid voltage fluctuations and waveform distortions, which enhances the accuracy and efficiency of the test data. The built-in advanced insulating materials and heat dissipation system ensure that the step-up transformer remains stable and reliable, enabling the tester to withstand long-term high-voltage breakdown tests. This protects operator safety and prolongs the service life of the tester.
4.Complete Protection System:
The GTD1001D includes various protection devices to ensure the safety of both the operator and the tester in cases of faults, such as low breakdown voltage of the oil or empty cup breakdown.
5.Multiple International Testing Standards:
The tester supports fully automatic test sequences for 12 common international standards and spot tests (Standards: ASTM D877 & ASTM D1816, IEC 60156).
6.Internationally Universal Stainless Steel Calipers:
The precise adjustment of standard electrode distances is facilitated by international universal stainless steel calipers.
7.Overall Shielding Technology:
The comprehensive shielding technology prevents all sources of electronic interference, ensuring a pure test environment.
8.Multilingual Technical Instructions:
The tester provides English operation pages and instructions available in 15 languages.
TECHNOLOGY SPECIFICATION:
|
Type |
GTD1001D Insulating Oil breakdown voltage(BDV) tester |
|
Output voltage |
0~80kV |
|
Minimum resolution |
0.1kV |
|
Accuracy |
±(2%×reading±0.2kV) |
|
Voltage raise speed |
0.5/1 .0/2.0/3 .0kV/s for option |
|
Switch-Off time on breakdown, ms |
≤1ms |
|
Experimental times |
1～6 for option |
|
Programmed test standard |
IEC60156/ASTM D877/ASTM D1816 |
|
Memory for result |
30 groups |
|
Volume of the oil cup |
200ml standard; 300ml and 500 ml option |
|
Gap between the poles |
2.5 mm (Electrode gap is adjustable) |
|
Temperature in operation |
0~40℃ |
|
Relative humidity |
≤80%RH, No dew |
|
Power supply in operation |
AC220V±10%, 50Hz±1% |
|
Volume / Weight |
Length 409 mm Width 393 mm Height 388 mm / 29kgs |
1. Clean and dry the oil test cup, standard gauge, glass rod for stirring and glass plate for covering the oil cup.
3. Rinse the oil cup three times with the sample oil. Use a gauge to adjust the distance between the electrodes of the oil cup (2.5 mm), then slowly inject the test oil into the oil cup along the stirring glass rod until it is ≥10 mm above the electrode, then cover the glass cover and let it stand still for 15 minutes to make the air bubbles in the oil overflow.
4. Then turn on the power supply, and increase the voltage evenly at a speed of 3~5kV/s until the oil cup electrode breaks down, and (KOF overcurrent trip) disconnect the power supply.
5. Use a stirring glass rod (about 2 mm in diameter) to gently move between the electrodes to remove carbon particles on the surface of the electrodes due to breakdown.
6. After stirring, stand still for 5 minutes and pressurize again.7. The breakdown should be repeated six times in total, the first time is not calculated, and the average value of the five breakdowns is taken as the final oil pressure resistance value.
8. If insulating oil BDV value is above 30 KV, transformer oil is good.
When a voltage is applied to the insulating oil, as the voltage increases, the current through the oil increases sharply, causing it to completely lose its inherent insulating properties and become a conductor. This phenomenon is called breakdown of the insulating oil. The critical voltage value at which the insulating oil breaks down is called the breakdown voltage or dielectric breakdown. The electric field strength at this time, called the dielectric strength of the oil, indicates the ability of the insulating oil to resist the electric field. The relationship between the breakdown voltage U (kV) and the dielectric strength E (kV/cm) is: E=U/d"
d"=The distance between the electrodes (cm).
Pure insulating oils have different breakdown mechanisms than insulating oils, which usually contain impurities.
The breakdown of the former is caused by the liberation, which can be explained by the mechanism of gas dielectric breakdown, that is, under high electric field strength, oil molecules collide and become free ions and electrons, thereby forming electron collapse. The electron collapses toward the anode, and the accumulated positive charge collects near the cathode, eventually forming a channel with high conductance, resulting in breakdown of the insulating oil.
Generally, insulating oils always contain more or less impurities, and in this case, impurities are the main cause of breakdown of insulating oil. The dielectric coefficient ε of water droplets, fibers and other mechanical impurities in oil is much larger than that of oil (ε=7 of fiber, ε=80 of water, and ε≈2.3 of transformer oil), so under the action of electric field, impurities It will be attracted to a region where the electric field strength is large, and an impurity "small bridge" is formed between the electrodes, thereby reducing the breakdown strength of the oil. If there are enough impurities, it can also constitute a "small bridge" that penetrates the gap of the electrode, and a large leakage current flows through it, causing it to generate heat, and partially boiling and vaporizing the oil and water, as a result, the breakdown is along the "air bridge."
Why is the transformer oil breakdown voltage test very important?
Insulating oil is widely used in liquid-filled high-voltage electrical equipment, such as power transformers, distribution transformers, transformers, bushings, oil-filled circuit breakers, oil-filled cables, oil-filled capacitors, etc. Insulating oil also acts as a coolant to dissipate electrical heat in the device. Therefore, the insulating oil should have good thermal conductivity and chemical stability at high temperatures, so before the insulating oil causes internal arcing or complete equipment failure, regular oil withstand voltage testing of transformers is an important preventive measure that will help keep the high-voltage equipment running normally, otherwise it will cause transformer failure or even casualties.
ASTM D1816, ASTM D877, and IEC 60156 are some of the popular standards that specify the dielectric strength or breakdown value and breakdown procedure for testing oil samples. The test procedure is to take a sample of insulating oil from the oil drain valve of the transformer and measure its breakdown voltage, the test voltage is applied to the electrodes immersed in the insulating oil at a constant, standard slew rate (eg 2kV/sec. The test can be carried out five to six times, and the average value of these readings can be considered as the breakdown voltage of the insulating oil under test.
The dielectric breakdown or breakdown voltage of the insulating oil should not be lower than the specified value of the recommended value. If the breakdown voltage is close to the specified limit, the sample must be subjected to further diagnostic tests such as oil resistivity and dielectric dissipation factor (tan delta) tests. As per IEEE standard, it is recommended that oil breakdown voltage tests be performed twice a year.
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Points to note in transformer oil breakdown voltage (BDV) test
