The behavior principle of DDL protection for DC feeder in DC traction current supply system and the setting principle of protection parameters are introduced and illustrative examples are given.是什么意思_The behavior principle of DDL protection for DC feeder in DC traction current supply system and the setting principle of protection parameters are introduced and illustrative examples are given.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句