关于水力发电机的问答
1.的允许温度
水电-
发电机是由里面的什么材料限制的?为什么?发电机的输出受允许温度的限制，而限制发电机允许温度的是绕在线材上的绝缘材料。所述保温材料具有适当的最大允许工作温度，在此温度范围内，可长期安全工作;超过这个温度，绝缘材料将很快老化，不再适用。
高温不一定会立即破坏绝缘材料。首先表现为绝缘的各种基本特性的恶化，如绝缘电阻和击穿电场强度的降低。特别是在长期高温作用下，绝缘材料加速老化。当受到电动势作用时，容易产生裂纹和断裂，从而丧失绝缘能力。因此，工作温度越高，绝缘材料的寿命越短。目前，在水力发电机组中使用最多的是B级绝缘。材料是B级橡胶云母带，称为黑色绝缘。另一种环氧玻璃粉云母带，俗称黄绝缘，耐热性为130℃。因此，电气运行规程中规定发电机定子绕组温度一般不超过90℃，最大不超过120℃，转子绕组温度不超过130℃。2. What effect does the change of the inlet air temperature of the air-cooled generator have on the operation of the generator? The rated capacity of the generator corresponds to the rated inlet air temperature. The rated inlet air temperature specified in my country is 40°C. The change of the allowable output value of the generator due to the change of the inlet air temperature should be based on the temperature of the coil and the iron core not exceeding the allowable value. When the inlet air temperature exceeds the rated value, if the stator, rotor winding and stator iron core If the temperature does not exceed the specified standard, the generator output may not be reduced; if it exceeds the standard, the current of the stator and rotor windings should be reduced to reduce the temperature to the specified value. When the inlet air temperature is lower than the rated value, the current of the stator and rotor can be greater than the rated value, but it can only increase until the temperature of the stator, rotor winding and stator core reaches the allowable temperature. Therefore, the inlet wind temperature directly affects the output of the generator.
为什么进风温度与发电机输出功率有这么大的关系?因为发电机铁芯和绕组的温度与进口温度和铜铁损耗有关。铜损耗与通过定子绕组的电流的平方成正比，铁损耗与铁芯中的磁通密度或电压的平方成正比。损失增加，温度升高。铁芯和绕组的最大允许温度是一个预定值，所以进风温度和允许温升之和不能超过该允许温度。因此，进风温度较高，允许温升应小。一般发电机的电压变化很小，温升与电流有关。如果允许温升很小，电流就必须减小。反之，当进风温度较低时，电流会增加。
1）缩合容易降低绝缘电阻;（2）过分铜线的高温度上升会导致过量的热膨胀和伸长，造成绝缘开裂;（3）绝缘变脆且容易损坏。因此，所述发电机的所述入口的需要封闭通风冷却空气温度应不低于15℃〜20℃下;与开放式通气发电机的冷却空气入口的温度应不低于5℃。在操作期间，风温度在发电机的入口和出口应仔细监测。为了避免过热和绝缘的老化，冷却气体的入口空气温度应不超过50℃，且出口温度应不超过75℃。通常，冷却气体的温度上升为约25℃至30℃。如果冷却气体的温度上升显著增加，则意味着此时，发电机的冷却系统工作不正常，并且应查明原因和消除。3.什么原因的水轮发电机改变出口和进口风温差？ The temperature difference between the outlet and inlet wind of the generator is related to the heat and air volume taken away by the air, the water volume and temperature of the cooling water, the heat transfer effect of the air cooler, and the internal loss of the generator. Under the same load, if there is a significant increase in the temperature difference between the outgoing and incoming wind, it means that the internal loss of the generator has increased, or the cooling system is abnormal. The former may be that a parallel branch of the stator winding (such as a welding head) is disconnected; the insulation between the strands is damaged; the iron core has a local high temperature. The latter may be the reduction of cooling water volume; blockage of the cooling pipeline; failure of the valve and falling of the core; contamination of the outer wall of the heat dissipation tube or scaling of the inner wall; local short circuits in and out of the cooling gas.
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