單項(xiàng)選擇題The voltage developed by an AC generator is controlled by varying the ()

A.speed of the prime mover
B.AC excitation to the field
C.DC excitation to the field
D.DC excitation of the voltage regulator


您可能感興趣的試卷

你可能感興趣的試題

1.單項(xiàng)選擇題Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ()

A.is good for long term preserving since most insulation is organic and contains some amount
B.lowers the insulation value and is a common cause of fault grounds in idle machines
C.will enhance insulation resistance only if it is fresh water and contains no salt
D.reduces the amount of current supplied or drawn by the machine so horsepower is limited

3.單項(xiàng)選擇題While paralleling two AC generators using synchronizing lamps only, both lamps will go dark when the generators are ().

A.running at the same speed
B.grounded
C.of the same polarity
D.in phase

4.單項(xiàng)選擇題Electric circuits are protected against overloads and short circuits by means of a/an ().

A.circuit breaker
B.amplifier
C.diode
D.capacitor

5.單項(xiàng)選擇題Ambient temperature is the ().

A.amount of temperature rise with no load
B.temperature of the compartment where the motor is located
C.normal operating temperature, less the room temperature
D.amount of temperature developed by an operating motor