Types of generators:
1. According to AC and DC: DC, AC.
2. Alternators are divided based on the number of phases: single-phase and three-phase.
3. According to the structure: salient pole and hidden pole.
4. Alternators are divided into pole pairs: one pole pair and two pole pairs. . .
5. According to the cooling method: air cooling, hydrogen cooling, water cooling, etc.
6. Depending on use: fixed, portable.
7. According to the main engine: steam turbine, diesel engine, gasoline engine, etc.
8. According to synchronous and asynchronous: synchronous and asynchronous. etc.
1. Reduce the purity of hydrogen in the generator. Lubricating oil flows inside the generator along the large shaft. After being mixed with hydrogen, an oil-hydrogen mixture is formed, which is then formed. projected by the rotating rotor at high speed to form a mistrd of atomized oil. The oil-hydrogen mixture with a low degree of atomization adheres to the windings, hydrogen coolers, end covers and other components at the end of the generator, then agglomerates and flows into the generator bottom with oil-hydrogen mixture; a high degree of atomization follows the flow in the generator chamber. Hydrogen enters the inside of the generator, thereby reducing the purity of the hydrogen in the generator chamber. Electricity industry regulations: “It is generally required that the purity of hydrogen in the generator be maintained above 96%. When it is lower than this value, the wastewater must be evacuated. Under normal circumstances, when the hydrogen pressure in the generator chamber remains unchanged, for every 1% decrease in hydrogen purity, the ventilation friction loss increases by approximately 11%, thereby reducing the 'effectivegenerator tee. Generator losses increase and the heat generated increases. Once the mist-form oil-hydrogen mixture follows the hydrogen gas for a certain distance, some or all of the lubricating oil can be separated from the hydrogen gas. As long as the working state of the generator remains unchanged and the oil leakage remains unchanged, an area with relatively low hydrogen purity will be formed in a certain part of the generator. Heat dissipation conditions in this area will deteriorate and heat accumulation will form. possibly causing local overheating of the generator. Local overheating of the generator will cause the generator stator bar insulation or iron core insulation to age or even fail.
2 If the humidity of hydrogen in the generator exceeds the standard, the humidity in the lubricating oil will cause the humidity to be exceededity of hydrogen in the generator chamber. Exceeding hydrogen humidity poses two risks:
(1) Excessive hydrogen humidity caused a short circuit accident at the end of the generator stator coil . The higher the humidity of hydrogen gas, the more moisture in hydrogen gas, the lower the dielectric strength of the gas. The stator winding is affected by humidity and the insulation resistance is reduced, thereby reducing the discharge voltage on the insulation surface. The porcelain insulating sleeve of the generator end wire is prone to flashover along the surface, causing a short circuit accident at the end. In the energy sector, similar accidents have occurred.
(2) Excessive hydrogen moisture causes stress corrosion in the generator rotor protection ring. High humidity of hydrogen causehas stress corrosion on the metal it contacts, and the stress corrosion and metallic hydrogen embrittlement will catalyze each other, aggravating the corrosion of the generator rotor retaining ring. In severe cases, stress corrosion cracks will appear. the generator rotor retaining ring. According to relevant information, for retaining rings made of materials other than 18Cr18Mn, if the relative humidity of hydrogen is greater than 50%, stress corrosion will occur quickly.Acceleration; Even if the retaining ring is made of 18Cr18Mn material, when the relative humidity of hydrogen is greater than 80%, it will also cause stress corrosion in the retaining ring of the generator rotor. Due to stress corrosion, the retaining ring cracks and the insulation tiles become loose, causing friction between the insulation tiles and therotor coil at the end of the retaining ring, which can cause the generator rotor coil to ground or short.