单项选择题
A.temperature rise B.input kilowatts C.horsepower D.operating voltage
When would you ground an electric hand tool?（）A.When it...
单项选择题When would you ground an electric hand tool?（）
A.When it is a DC machine B.When it is an AC machine C.Any machine that operates on over 100 volts D.Only when working on wet steel plates
The load between two steam-driven alternators operating...
单项选择题The load between two steam-driven alternators operating in parallel may be adjusted by varying （）
A.the speed of the alternators B.the field strength of the machines C.the power factor of the alternators D.steam supply to the prime movers
The purpose of the commutator and brushes on a DC gener...
单项选择题The purpose of the commutator and brushes on a DC generator is to（）
A.change AC to DCcurrent B.change DC to AC current C.neutralize a armature reaction D.carry current to the outside circuit
