单项选择题
A.voltage regulators B.field rheostats C.reverse power relays D.prime mover governors
In a three-phase circuit, the phase voltages are （）A.12...
单项选择题In a three-phase circuit, the phase voltages are （）
A.120°apart B.160°apart C.180°apart D.360°apart
The frequency of an alternator at a given RPM is determ...
单项选择题The frequency of an alternator at a given RPM is determined by the （）.
A.number of turns of wire in the armature coil B.number of magnetic poles C.strength of the magnets used D.output voltage
The pushbutton on the handset of a ships sound-powered ...
单项选择题The pushbutton on the handset of a ships sound-powered telephone must be depressed to （）.
A.talk then released to listen B.listen then released to talk C.both talk and listen D.ring the station being called
