单项选择题
A.means of rheostat the governor settings B.a balance coil excitation C.adjusting the governor settings D.changing excitation
If a voltmeter is connected across a line, it must be p...
单项选择题If a voltmeter is connected across a line, it must be protected with a（）
A.shunt B.high-resistance coil in the armature circuit C.low-resistance coil in the armature circuit D.shunt and a coil of high resistance
When current and voltage reach maximum values at the sa...
单项选择题When current and voltage reach maximum values at the same time, the power factor is（）
A.minimum B.maximum C.leading D.lagging
Which is an acceptable means of correcting high mica be...
单项选择题Which is an acceptable means of correcting high mica between commutator bars?（）
