Since water is conductive when passing through it, ordinary meggers cannot measure accurately and the measured resistance is very low.
The insulation classification of the double water internally cooled generator is measured
1. The situation measured with a special dual-water megger is: water enters the stator through the coil; the insulation resistance should be greater than 30KΩ; The water-cooled engine should be tested with flowing water. The conductivity should not be higher than: 2.0 × 102 μS/m2 when the water temperature is 20°C. The stator coil is cleaned after the measurement.
If it is a water-cooled generator, a special water agitator should be used when measuring the insulation of the stator, and the water pipe part must be shielded and connected.
1. When measuring insulation, it is not necessary for water to pass through it. When there is noas water, the stator is qualified if measured with a megometer and above 2 M; when the water in the coil is not dried, it is measured with shielded wiring method by megohmmeter. After the water passes, it is measured with water. - Cooled motor insulation tester, and all are qualified above 6M.
2. The water collection ring and the external fixed cold water pipe are isolated by the connection flange.
3. Since the external fixed cold water pipe is grounded, what is protected is: the leakage current generated in the water after the megger is pressurized.
What is used to cool the generator of the water cooled unit? Air? You're unlikely to use water, right?
A generator that uses a hydraulic turbine as the prime mover to convert water energy into electrical energy. A hydrogenerator is made up of main componentsaux such as a rotor, a stator, a frame, a thrust bearing, a guide bearing, a cooler and a brake (see figure). The stator is mainly composed of frame, iron core, winding and other components. The stator core is made of cold-rolled silicon steel sheets and can be made into integral or split structures according to manufacturing and transportation conditions. The cooling method of hydraulic generator generally adopts closed circulation air cooling. Very large capacity units tend to use water as the coolant to directly cool the stator. If the stator and rotor are cooled at the same time, it will be a water turbine generator set with double internal water cooling.
The generator set is composed of two main parts: a main engine (diesel engine, gasoline engine, steam turbine, etc.) and a generatortor;
The so-called water-cooled unit refers to the use of water to cool the generator (not to mention the main engine, it must be cooled with water);
The water-cooled unit has dual internal water cooling and single internal water cooling; that is, both the stator and rotor are wired and internally cooled by water, which is called dual water internal cooling, only the stator is cooled with water and the rotor is cooled with hydrogen, which is a unique internal water cooling. cooling. (Large generators generally no longer use air cooling, but generally use hydrogen, because the mass of hydrogen is much smaller than that of air and its thermal conductivity is much better, which can greatly improve cooling efficiency while water has high heat capacity and better.r cooling effect, but it is difficult to enlarge it)