Views: 0 Author: Site Editor Publish Time: 2014-04-07 Origin: Site
According to the principles specified in the procedure, for the generator-transformer group, when the generator voltage circuit three opposing the capacitance current is greater than 5A, the arc coil compensation should be installed, and the ground protection movement is transmitted to the signal (when the ground protection current is less than 5A). When there is a short-circuition protection, it is considered that the grounding capacitor current is less than 5A, allowing the floor to be run in a short time, and the time is properly transferred and then stopped. According to this standard, the burns depth does not exceed the specified value when the ground capacitance current exceeds 5A. At present, due to the high use of water-cooled large generators, complex cooling methods must be used, not only the auxiliary ventilation slots, but also axial cooling channels, etc., which makes the iron core maintenance difficulty, and the economic loss caused by shutdown maintenance . Therefore, the allowable value of the stator ground capacitor current must be further discussed in conjunction with the actual operational experience.
When the generator neutral point is grounded by the power distribution transformer, in normal case, the three harmonic voltage of the neutral point will always be less than the three harmonic voltages of the unit, and the amount of braking amount is less than the amount of operation, the protection will be protected. Will malfunction. Therefore, when we use 100% stator winding to ground protection, we should pay special attention to the grounding mode of the generator neutral point, and cannot be generalized.
The above is the introduction of the theoretical analysis and practical application for stator ground protection. In the specific engineering design and domestic bidding production, the stator grounding protection is used in three harmonics and zero-sequence voltage, and the application is wide; some foreign projects Then be used to adopt an injection principle stator grounding protection, which mainly considers the problem that there is no stator ground protection when the start-hour is turned on.