求翻译：4．WM和WM动力盒连接后即开始工作，在连续使用超过30分钟后会有发热现象，这属于正常现象，使用 者不必担心。是什么意思？

4. WM or WM power box after the connection is working, in more than 30 minutes of continuous use will have a fever, which is normal, users don't have to worry about.