Six doubt and answer of air compressor lubricating oil
1. Why flat electrode is used in the pressure test of lubricating oil?
The flat electrode used in spark discharge of lubricating oil withstand voltage test is easy to connect the impurities in the oil into a "small bridge" because of the uniform electric field distribution between the electrodes, so the spark discharge voltage is largely determined by the amount of impurities.
If a spherical electrode is used, it is not easy to form a "small bridge" because the electric field intensity between the spheres is relatively concentrated, impurities have more chances to touch the sphere, and after receiving the electric charge, they are removed by a strong electric field.
The purpose of lubricating oil pressure test is to check the impurities such as moisture and fiber in the oil, so it is better to use flat electrode.
2. What kinds of commonly used lubricating oil are there? What is the scope of application?
There are three kinds of lubricating oil commonly used in air compressor engineering: lubricating oil, capacitor oil and cable oil. Four
(1) Lubricating oil brands include DB -? 10, DB -? 25 and DB -? 45, which are suitable for insulation and heat dissipation in general transformers and oil circuit breakers. In addition, there are ultra-high pressure lubricating oil, etc.
(2) There are two brands of capacitor oil: DD-1 and DD2, among which DD-1 is suitable for insulation on Power Industrial capacitors and DD-2 is suitable for insulation on telecommunication industrial capacitors.
(3) Cable oil can be divided into two types: 0 is used as the insulating paper of solid cable to receive oil, which is used on cables with 35kV and below; @ high voltage cable oil is used as the insulating oil of self contained oil filled cables with 330kV and below.
3. Why does the lubricating oil age?
Lubricating oil is made from oil. It is a mixture of various hydrocarbons, resins, acids and other impurities. These substances are not stable. Under the action of temperature and other factors, they will continuously oxidize.
Temperature has a great influence on the lubricating oil. The higher the temperature is, the more serious the oil oxidation is. When the temperature is over 10, the oil will be destroyed due to the high temperature thermal splitting.
In addition, light, electric field and metals, impurities and gases in the mixed oil all play a catalytic role in the oxidation of oil, which will accelerate the development of oxidation. And the oxidation makes the indexes of oil worse.
4. How to judge the aging of lubricating oil?
When the lubricating oil is aged, it can be observed that the color of the oil changes from light yellow to dark, from transparent to turbid. At the same time, viscosity, water content, acid value and ash are all increased, and a large number of sludge is separated from the oil.
5. What are the main properties of lubricating oil?
The main properties of lubricating oil include insulation strength, viscosity, freezing point, density (formerly known as specific gravity), ash content, acid, alkali, sulfur and other impurities, acid value, stability, pH value, etc.
6. How is the insulation capacity of lubricating oil regulated?
The insulation capacity of lubricating oil, that is, the strength of air compressor, refers to the breakdown of lubricating oil when it is applied with high voltage under specified conditions. The higher the value, the better. The test criteria are as follows:
(1) For new oil, air compressor equipment of 15kV and below is 30KV; air compressor equipment of 15-35kv is 35kV.
(2) For the oil in operation, the equipment of 15kV and below is 25kV; the air compressor equipment of 15-35kv is 30kV.2