General Electric licensed Bakelite as an insulator in 1909, then began to develop its own resins.
通用电气在1909年授权生产胶木绝缘体，然后开始开发自己的树脂。
2
The polarity of impulse voltage and the polarity of insulator surface electric charge can affect the corona initial time of insulator, the change time - interval and the corona current.