绝大部分水电站同步发电机的转子磁场电流,都是由具有换向器的励磁机供给,而换向是励磁机能否长期安全运行的关键问题之一。换向过程不仅是电磁现象,同时还出现机械、电化学、电热等方面的现象,彼此相互影响。换向不良表现在电刷下发生火花, Most of the synchronous generator rotor power field current, are supplied by the exciter with the commutator, commutation is one of the key issues in the long-term safe operation of the exciter. The commutation process is not only an electromagnetic phenomenon, but also occurs in the mechanical, electrochemical, electric and other aspects of the phenomenon of mutual influence. Poor performance in the brush under the spark,