單項選擇題

To parallel an incoming machine to a running machine therefore it is necessary to ensure firstly that （）.

A.two frequencies must be brought into phase
B.the incoming machine accepts a small amount of load
C.the running machine must be unload
D.both voltages are equal

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單項選擇題

The magnetic field is provided by electromagnets so arranged that adjacent poles have （）.

A.opposite polarity
B.the same polarity
C.negative polarity
D.positive polarity

單項選擇題

An a-cswitchboard is usually（） the corresponding d-cboard because of the higher voltage and lower currents and smaller bus-bars.

A.larger and heavier than
B.as much as
C.smaller and lighter than
D.more dangerous than

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To parallel an incoming machine to a running machine therefore it is necessary to ensure firstly that （）.

你可能感興趣的試題

The magnetic field is provided by electromagnets so arranged that adjacent poles have （）.

An a-cswitchboard is usually（） the corresponding d-cboard because of the higher voltage and lower currents and smaller bus-bars.