09,22,2026 15 views
Precautions for use:
1. Poor quality oil testing equipment is prone to damage
Recycled unfiltered oil is called inferior oil, which contains a considerable amount of moisture and impurities. Its insulation and electrical strength are mostly below 12KV. Especially for low-quality oils with high moisture content, some users use instruments to measure insulation strength in order to determine the degree of deterioration, which can easily cause damage to the high-voltage testing system of this instrument.
Under normal circumstances, the high-voltage electrodes are filled with insulating oil. During testing, the voltage between the two electrodes continues to increase, and oil media with different insulation strengths can withstand high voltage electric fields of different values. This constantly rising high voltage electric field causes the insulation oil media to be suddenly broken down when it cannot withstand it. The transient high current during breakdown is collected by the instrument and immediately tripped to switch from high voltage to voltage reduction operation.
When testing low-quality oil with high moisture content, the voltage between the two hemisphere electrodes continuously increases, and at the same time, water particles in the oil medium are adsorbed to the gap between the spheres under the action of a high-voltage electric field, forming a light white mist like water column, which becomes finer and coarser, and the water resistance becomes smaller and smaller. The transient process of reducing water resistance and increasing the current of the high-voltage transformer (without breakdown and sudden discharge) can cause damage to the instrument, resulting in current limiting resistors, fuse burnout, and even burning of the instrument's high-voltage transformer.
2. Testing of low pressure oil medium
This type of oil medium is usually between 15-35KV. Even if the oil medium contains trace amounts of moisture and impurities, the instrument can still test it normally. However, during the pressure rise process, some individual bubble particles (or impurities) are adsorbed between the ball gaps, causing discharge. The bubbles are dispersed and squeezed out of the ball gaps, and the oil is replenished. Therefore, the pressure continues to rise until the maximum bearing point of the oil medium is broken down, and this test data is still reliable.
3. Testing of inferior oil
Do not forcefully use instruments for testing visible water droplets or impurities in the oil medium to be filtered during recycling. In low-quality oil media stored for more than 24 hours, large water droplets settle on the bottom layer of the oil, while fine particles and bubbles float on top of the oil. The user needs to use an instrument without water pollution to extract the oil sample from the middle part, and closely observe whether there is a fine wire like mist column as shown in Figure 9 when the pressure is increased (from the beginning of the pressure increase period) during the test. If it is found, the power should be immediately turned off and the test should be stopped. Or if multiple continuous discharges occur during the boosting process and the instrument cannot automatically disconnect, the user should immediately turn off the power and stop the test.
