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.
When purchasing a water cooling meter (insulation resistance tester for water cooled generators), there are two main points to note: First, the method Generator cooling should be water-cooled rather than water-cooled. than air cooled. The instrument is only intended for generatorss water-cooled; second, select the voltage level and range. There are three main types of water jerk meters (insulation resistance testers for water-cooled generators) in the market based on voltage level: 2500V/10G, 5000V/20G and 2500 V/5000 V/20 G. They vary depending on the voltage level. and generator capacity. Make your selection. Third: Second, choose instruments that can automatically compensate and eliminate the impact of water polarization potential on measurement results. Automatically measure R15, R60 and R600 and automatically calculate absorption rate and polarization index. The test voltage is negative high voltage 2500V, and the charging capacity of 5000V is strong. When the resistance (water resistance) between the winding and the water collection pipe is as low as 70kΩ, the test voltage drops <10%. The beach of mesure is 0 to 20 GΩ and the range is automatically switched. It can automatically compensate and eliminate the influence of water polarization potential on test results. When the resistance between the water collection pipe and the machine base is as low as 3kΩ, the measurement accuracy can still be guaranteed.