单项选择题
A.power B.efficiency C.effective power D.power factor
The overcurrent relay （） the motor contactor when the m...
单项选择题The overcurrent relay （） the motor contactor when the motor exceeds its rated current.
A.connects B.trips C.fouls D.destructs
In a modern three-phase A-Csynchronous brushless genera...
单项选择题In a modern three-phase A-Csynchronous brushless generator, the excitation winding is on the rotorThat means （）.
A.The generator needs not excitation B.The winding on the rotor is for inputting excitation current C.There are three phase windings on the rotor D.The generator has brushes
Ammeter is to measure the （）.A.currentB.voltageC.powerD...
单项选择题Ammeter is to measure the （）.
A.current B.voltage C.power D.frequency
