Established in 1997 within the Installation and Operation Unit, this section of the Moham Shargh Company is responsible for performing periodic oil testing on power transformers in Khorasan Province.

The oil laboratory takes advantage of advanced facilities and up-to-date equipment and is able to do a wide variety of approved oil tests on reactors and transformers. It utilizes the experience of skilled and compassionate professionals to give service to all the regional substations.

The main activities ongoing in the lab are as follows:

• Gas chromatography test
• Oil quality control tests
• Quality control test of SF₆ gas
• Furfural test
• "Thermovision" thermal imaging
• Electrical tests of high-pressure outdoor substations equipment

Gas Chromatography Test

This is one of the most important testing methods to detect developing defects in transistors. The duty of the gas chromatography device is to use dissolved gas analysis in the transformer's oil to detect active faults. The analysis is used to assure the accurate performance in transistors and to prevent possible accidents.

Oil Quality Control Tests

Transformer oil is responsible for insulating, cooling and protecting internal components of the transformer. Being detailed in the IEC 60422 standard, the oil quality control tests are used to determine the accuracy of oil performance in relation to the above tasks.

• Oil physical tests determine the quality of oil physical properties. The tests include density at 20°C, surface tension, viscosity at 40°C and 100°C, pour point and flash point.
• Oil chemical tests determine the quality of oil chemical properties. The tests include humidity, acidity and determination of oil toxicity (PCB).

PCB is a highly toxic material which exists in environmental resources such as water and food due to its stability. PCB is one of the most significant sources of environmental pollution used to form insulation oils in the past. With the oil toxicity test, PCB is detected in insulation oil and further actions such as collection and degradation are done.

• Oil electric tests determine the insulation status of the oil, and the oil's electric stress is measured by comparing it with oil resistance standard values. The tests include voltage failure, tangent delta and resistivity at 90°C.

Quality Control Test of SF₆ Gas

Sulfur hexafluoride (SF₆) is an excellent material to cut off the electric arc. The SF₆ gas cools the heat due to electric arc's high energy well, and its electronegativity makes it tolerant of high voltages. Under similar conditions, the ability of SF₆to cut off is a hundred times higher than air, and its electrical resistance is 2.5 to 3 times higher than air. Therefore, any pollution in SF₆ gas composition may lead to equipment damage or malfunctioning. The laboratory includes humidity devices (laboratory-portable workshop), purity devices (laboratory gas chromatograph, laboratory-portable workshop) and acidity devices (laboratory-portable workshop).

Furfural Test

The main determinant of transformer life is paper. Cellulose insulation's degradation and disintegration of electrical solid materials filled with oil lead to the formation of some specific compounds such as furan derivatives. Despite the fact that furan derivatives are a large share of the remainder absorbed on paper, they are partially soluble in oil. Measurements of these values indicate the transistor paper condition.

"Thermovision" Thermal Imaging

One of the preventive actions in the electricity industry is "Thermovision" thermal imaging. In this operation, all existing connections are thermally evaluated. If a defect is observed, a color image report is prepared for the Repair Group to take action to fix it.

Electrical Tests of High-Pressure Outdoor Substation Equipment

Some of the tests in this sector include high-voltage cable test, CB test, CT and CVT tests, VT test, AS and LA tests, ED test, DS and DSE tests, continuity of earth network connections, earth network resistance, soil resistance and tangent delta.

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