单项选择题
The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the（）.
A.loss of residual magnetism
B.absorption of moisture in the insulation
C.insulation varnish flaking
D.dirt collecting on the windings
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相关考题
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单项选择题
The Wheat-stone bridge is a precision measuring instrument utilizing the principle of changes in（）.
A.inductance
B.capacitance
C.resistance
D.amperage -
单项选择题
Which of the motors for the devices listed below is fitted with an instantaneous overload relay?（）
A.Fan
B.Pump
C.Winch
D.Machine tool -
单项选择题
One factor that determines the frequency of an alternator is the（）.
A.number of turns of wire in the armature coil
B.number of magnetic poles
C.strength of the magnets used
D.output voltage
