When the lightning wave is transmitted to the generator, the steepness of the wave directly threatens the turn to turn insulation, especially the first few turns. The steeper the wave is, the higher the voltage between the first few turns is, and the easier the turn to turn insulation is damaged. The magnitude of lightning wave threatens the main insulation of generator. The larger the amplitude of lightning wave, the higher the voltage between the wire and the core, and the easier the insulation is to be broken down. Therefore, lightning protection measures must be taken for generators.

對發電機來講，防雷措施的要求是要把雷電波的幅值和陡度限制在容許的范圍內，以消除對發電機的危害。

For the generator, the requirement of lightning protection measures is to limit the amplitude and steepness of lightning wave within the allowable range, so as to eliminate the harm to the generator.

對有架空直配線路的發電機的防雷措施當流過發電機母線上FGD系列閥型避雷器的電流不超過3KA時，發電機的耐雷水平為50KA，發電機的防雷保護接線及其設備的選擇都按此條件考慮。

For the lightning protection measures of the generator with overhead direct distribution line, when the current flowing through the FGD series valve type arrester on the generator bus does not exceed 3KA, the lightning withstand level of the generator is 50kA, and the lightning protection wiring and equipment selection of the generator are considered according to this condition.

其防雷方式一般包括兩部分：一部分是裝設在母線上的閥型避雷器及吸收電容器，避雷器的作用是限制雷擊波的幅值，吸收電容器的作用是限制波的陡度；另一部分是進線保護，它的作用是對進線上傳來的較強雷電波先進行一次削弱。發電機的防雷方式很多，可根據發電機容量、雷電活動的強弱和對供電可靠性的要求確定。

The lightning protection method generally includes two parts: one is the valve type arrester installed on the bus and the absorption capacitor. The function of the arrester is to limit the amplitude of lightning wave, and the function of the absorption capacitor is to limit the steepness of the wave; The other part is the incoming line protection, whose function is to weaken the stronger lightning wave from the incoming line. There are many lightning protection methods for generators, which can be determined according to the generator capacity, the intensity of lightning activity and the requirements of power supply reliability.

不論采用哪一種保護方式，一般應將母線處的來波陡度限制在7.5KV/μs以下；發電機處的來波陡度限制在5KV/μs以下；流過母線上的沖擊電流幅值限制在3KA以下。

No matter which protection method is adopted, the incoming wave steepness at the bus should be limited to 7.5kv/ μ S or less; The steepness of incoming wave at generator is limited to 5kV/ μ S or less; The amplitude of impulse current flowing through the bus is limited to 3KA.