GTD1001D Insulating Oil Breakdown Voltage (BDV) Tester:

GTD1001D Insulating oil breakdown voltage tester adopts completely new electromagnetic compatibility concept(EMC) which designed to avoid tester crash accident during testing, and also can still work well in high magnetic field.

GTD1001D also use advanced  voltage breakdown control technology which will keep breakdown energy in a very low level, that will avoid pollution to oil sample during testing and make sure the test result are accurate and reliable.

The unique advantage of this tester lies in the built-in electronic boost system, the voltage regulation power supply adopts an electronic inverter sine wave generator, the voltage output is accurate, the waveform quality is high, and it is not affected by the grid voltage fluctuation and waveform distortion, making the test data more accurate and efficient. . The built-in advanced insulating material and heat dissipation system make the built-in step-up transformer stable and reliable, which can make the tester withstand long-term high-voltage breakdown tests, protect the safety of operators, and prolong the service life of the tester.

Feature
1. Reliable testing processing:
With electromagnetism compatibility(EMC) to avoid tester crash in test process, so the insulating oil breakdown voltage tester can work well in high-intensity electromagnetic environment,
2. 0 ~100kV  Stable and Precision Test Voltage:
With 0~100kV stable output and adopts completely new breakdown voltage control technology(RBM) to make the breakdown discharge energy to the lowest,which avoid oil sample pollution during test process and make test results reliable and accurate.Also GTD1001D got ILAC.MRA Standard Calibration Certification.
3. New type oil cup:

GTD1001D oil cup is made by new material with high strength and long service life to avoid fragile and leakage problem during testing.

4. Complete protection system:

GTD1001D has a variety of  protection devices which will make sure the safety of operator and tester itself in accident like inferior oil breakdown voltage and empty cup breakdown.

5. Multiple international testing standards

Fully automatic test sequences for 12 common test standards around the world and spot tests（Standard: ASTM D877 & ASTM D1816, IEC 60156）

6. International universal stainless steel calipers

Precise adjustment of standard electrode distances

7. Overall shielding technology

Perfect overall shielding technology can prevent all sources of electronic interference to ensure a pure test environment

8. Provide multilingual technical instructions

Provide English operation page and operation instructions 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

Insulating Oil BDV Testing Procedure

1. Clean and dry the oil test cup, standard gauge, glass rod for stirring and glass plate for covering the oil cup.
2. Use a clean and dry oil sample bottle to take oil samples at the sampling port of the transformer (the sampling port should be cleaned, dried and processed), insulating oil should be cooled down to 27°C temperature before testing.
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.

Transformer insulating oil BDV test result:

What is the Breakdown Voltage/Dielectric Breakdown (BDV) of Transformer Insulating Oil?

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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