Because the quality of the transformer oil will directly affect the subsequent operation of the transformer, and will also have a certain impact on the maintenance; so the transformer oil test is an important link in the operation and maintenance of power equipment, and is one of the effective means to ensure the safe operation of the power system.

Whether for the new transformer or the transformer in operation, the following tests should be conducted according to the operating procedures:

First, the flash point measurement method (closed-mouth cup method).

Under continuous mixing, the sample can use a constant, relatively slow speed for heating treatment, and also can achieve stirring between the specified temperature interval, and then introduce the small flame in the cup, when the test flame caused sample steam and flash, then the closed flash point temperature is the lowest. Among the main monitoring projects of electrical insulation oil, the closed mouth flash point is one of the main projects, and also an important safety indicator.

Second, the water-soluble acid determination method (PH value method).

Under the specified conditions, the sample is mixed and shaken with the same volume of distilled water, and then the water is extracted, and then the PH indicator is added to it, so that the color can be compared with the standard PH buffer solution, and the PH value is finally determined.

Third, the acid value determination method (alkali orchid 6B method).

The acidic component in the oil sample can be extracted with boiling ethanol, and then the standard solution of potassium hydroxide ethanol is titrated. The alkali orchid 6B is used as an indicator, and then the focus can be determined according to the specific change of color, in mgKOH / g. For the new transformer oil and the transformer oil in operation, using the acid value to evaluate is an important index that cannot be ignored.

Fourth, the breakdown voltage determination method.

Using special equipment, under the actual action of the AC electric field with continuous boost at a certain speed, the tested sample will run until the transformer oil is penetrated, at this time the breakdown voltage unit is recorded as kV. The breakdown voltage of electrical insulation oil is a comprehensive evaluation of the actual degree of the adaptive electric field voltage strength, and also one of the main contents of the evaluation of electrical performance control index.

Fifth, the dielectric loss factor measurement method.

The loss angle of the insulating medium is the phase Angle between the external AC voltage and the current flowing through the medium, and is expressed by the tangent value of the medium loss angle. The dielectric loss factor is called. The dielectric loss factor of electrical insulation oil is of great significance to judge the refining and purification degree of new transformer oil, the aging depth of transformer oil in operation, and the insulation characteristics of transformer. Therefore, it is one of the important indexes to monitor the electrical performance of electrical insulation oil.

Sixth, moisture determination (Coulomb method).

The moisture in the electrical insulating oil has great harm to the electrical performance, physical and chemical performance of the insulating medium and the life of the oil filling equipment, so the moisture is one of the important items of oil quality supervision.