| 摘要 |
PURPOSE: To provide an electronic protective relay comprising a detection element being used in conjunction with a polyphase electric load and delivering a signal indicative of the square of the strength of phase current directly, and an electronic processing circuit for processing that signal and delivering a trip signal. CONSTITUTION: Each detector element comprises a magnetic circuit formed by an identical L-shaped stator armature 11 and a movable armature 12 fixed to align respective leading ends and trailing ends, an armature winding 20 for passing the phase current formed by winding a coil around the longer leg of the L-shaped stator armature, and a piezoelectric plate 22 fixed to abut against the shorter legs of two L-shaped stator armatures 11, 12 such that a compressive pressure is applied when the movable armature 12 is attracted to the stator armature 11. |
