单项选择题
A.time-delay protection
B.short-circuit protection
C.short duration surge protection
D.sustained overload protection
单项选择题 The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains （）.
单项选择题 What will be the phase angle relationship of a six-pole, three-phase, rotating field generator （）.
单项选择题 The part of a fuse that melts and opens the circuit is made of （）.