[电] voltage and power directional re-lay

diàn yā hé gōng lǜ fāng xiàng xìng jì diàn qì ㄉㄧㄢˋ ㄧㄚ ㄏㄜˊ ㄍㄨㄥ lv4 ㄈㄤ ㄒㄧㄤˋ ㄒㄧㄥˋ ㄐㄧˋ ㄉㄧㄢˋ ㄑㄧˋ