单项选择题
A.can be reset to energize the circuit
B.should open the circuit when overloaded
C.will burn out when an over current flow develops
D.All of the above
单项选择题 An electrical device which prevents an action from occurring until all other required conditions are met is called a/an （）.
单项选择题 The frequency output of an operating alternator is controlled by the （）.
单项选择题 The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the（）.