单项选择题
A.time-delay protection B.short-circuit protection C.short duration surge protection D.sustained overload protection
The main difference between a motor control circuit con...
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 （）.
A.a magnetic operating coil B.normally open line contacts C.thermal-overload protection D.a momentary-contact start button
What will be the phase angle relationship of a six-pole...
单项选择题What will be the phase angle relationship of a six-pole, three-phase, rotating field generator （）.
A.60 B.120 C.180 D.360
The part of a fuse that melts and opens the circuit is ...
单项选择题The part of a fuse that melts and opens the circuit is made of （）.
A.copper and antimony B.steel and babbitt C.aluminum or beryllium alloy D.zinc or an alloy of tin and lead
