单项选择题
Self-excited a-cgenerator with "error operated" voltage control systems draw the full excitation power for the machine terminalsThis dispenses with the current transformers, reactors and capacitors necessary for accurate compounding, but renders the excitation system vulnerable to variations in its output voltageWhich of the following is correct about the generator mentioned according to the sentences above （）.
A.It consumes no excitation power
B.It has current transformers
C.Components are needed for accurate compounding
D.Its excitation system is vulnerable to voltage variations
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相关考题
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单项选择题
Generators should have an excitation/voltage regulation system which will enable them to share the steady state reactive load （） no machine exceeds its proportional share of reactive load by more than 10% of the rated reactive load of the largest generator.
A.when
B.so as
C.such that
D.though -
单项选择题
If a steering motor becomes overloaded, the （）
A.overload condition of 5 % will trip the motor off the line immediately
B.overload condition will be indicated visually in the machinery space
C.motor running indicator will begin to flash "on" and "off" in response to the sustained overload condition
D.standby steering pump will start automatically and come on the line -
单项选择题
When there is a fire in a large electric motor, normally the very FIRST step is to （）
A.secure the electric supply
B.ventilate area to remove smoke
C.start the fire pump and lead out hose
D.apply foam
