单项选择题
A.are less expensive B.require less maintenance C.can be started across the line D.offer a more effective means of controlling speed
Which of the following devices are protected from being...
单项选择题Which of the following devices are protected from being motorized by a reverse-power relay?（）
A.Alternators B.Wave guides C.Exciters D.Amplidynes
If the length of a wire is halved and the cross-section...
单项选择题If the length of a wire is halved and the cross-sectional area is doubled, the resistance will be （）
A.quartered B.unchanged C.doubled D.quadrupled
AC and DC generators are similar in that they （）A.both ...
单项选择题AC and DC generators are similar in that they （）
A.both generate alternating voltages B.both rectify the voltage before delivery C.are constructed at the same physical size for the same kilowatt rating D.both supply three-phase power
