What is the breakdown voltage value principle of transformer insulating oil
2018/5/17 Viewers:
If the insulation oil is installed in an oil cup with a pair of electrodes, if the voltage applied to the insulating oil increases gradually, when the voltage reaches a certain value, the oil resistance almost suddenly drops to zero, that is, the current abruptly increases and is accompanied by the form of medium (oil) with sparks or electric soliton, usually called oil "penetrated", oil. The critical voltage that is breakdown is called breakdown voltage, and the electric field intensity at this time is called the insulation strength of the oil. This shows the ability of insulating oil to resist the electric field.
Usually breakdown voltage U (kV) and insulation strength E (kV/cm) pressed calculation.
If the breakdown voltage U is used instead of the insulation strength E to represent the insulation characteristics of the oil, the distance between electrodes must be changed. If d=1cm is set in the above formula, the breakdown voltage of E=U. is equal to the insulation strength. Although the two meanings and units are different, they can be used to represent insulation performance of insulating oil. Therefore, the breakdown voltage and insulation strength of conventional oil are universal.
Electric shock is the main form of oil being penetrated. There are always certain amounts of free ions in the oil. The ion of the surface of the electrode begins to move from one electrode to the other because of the ionization. The speed of ion increases with the increase of voltage and the number of ions increase rapidly. Under the action of strong electric field, they will increase the current rapidly and cause the insulating oil to be penetrated. This breakdown generally requires a higher voltage, so the breakdown voltage of the new oil generally is higher.
It is well known that, although the insulating oil is refined, it is inevitable to absorb and mix the dust, fiber, or oxidation products in the process of transportation and storage. Under the action of strong electric field, these impurities (especially the polar impurities) will polarize, and are arranged along the electric field, forming a guide between the electric fields. The "small bridge" of electricity, which causes the oil to be penetrated. This is the so-called "small bridge" theory.
From the mechanism of the above oil being knocked out, or the practical experience, the main reason for the oil to be penetrated is that the external impurities are caused by the contamination of the oil, which is not related to the chemical composition of the oil itself. Therefore, in practice, when the breakdown voltage of oil is not qualified, especially new oil, it is only necessary to carry out filtration, such as filtration, and to remove the impurities and moisture in the oil, and the breakdown voltage of the oil can be reached.
Usually breakdown voltage U (kV) and insulation strength E (kV/cm) pressed calculation.
If the breakdown voltage U is used instead of the insulation strength E to represent the insulation characteristics of the oil, the distance between electrodes must be changed. If d=1cm is set in the above formula, the breakdown voltage of E=U. is equal to the insulation strength. Although the two meanings and units are different, they can be used to represent insulation performance of insulating oil. Therefore, the breakdown voltage and insulation strength of conventional oil are universal.
Electric shock is the main form of oil being penetrated. There are always certain amounts of free ions in the oil. The ion of the surface of the electrode begins to move from one electrode to the other because of the ionization. The speed of ion increases with the increase of voltage and the number of ions increase rapidly. Under the action of strong electric field, they will increase the current rapidly and cause the insulating oil to be penetrated. This breakdown generally requires a higher voltage, so the breakdown voltage of the new oil generally is higher.
It is well known that, although the insulating oil is refined, it is inevitable to absorb and mix the dust, fiber, or oxidation products in the process of transportation and storage. Under the action of strong electric field, these impurities (especially the polar impurities) will polarize, and are arranged along the electric field, forming a guide between the electric fields. The "small bridge" of electricity, which causes the oil to be penetrated. This is the so-called "small bridge" theory.
From the mechanism of the above oil being knocked out, or the practical experience, the main reason for the oil to be penetrated is that the external impurities are caused by the contamination of the oil, which is not related to the chemical composition of the oil itself. Therefore, in practice, when the breakdown voltage of oil is not qualified, especially new oil, it is only necessary to carry out filtration, such as filtration, and to remove the impurities and moisture in the oil, and the breakdown voltage of the oil can be reached.
- Pre：The insulating oil treated by 2018/5/17
- Next：The significance of determinin 2018/5/17