A.they are usedB.the field windings are connected to th……

单项选择题A circuit that has one wire in contact with the hull of the ship is a（）

A.series circuit
B.grounded circuit
C.short circuit
D.closed circuit

单项选择题If two AC generators are to be operated in parallel, the load is distributed evenly by（）

A.means of rheostat the governor settings
B.a balance coil excitation
C.adjusting the governor settings
D.changing excitation

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

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

单项选择题Which is an acceptable means of correcting high mica between commutator bars?（）