单项选择题
A “dead front” switchboard is one （）.
A.without switches on it
B.with insulated switches and no exposed terminals
C.without circuit breakers
D.without safety hand nails nor rubber mats
相关考题
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单项选择题
The total resistance of a parallel circuit is always （）.
A.larger than the greatest branch resistance
B.smaller than the lowest branch resistance
C.equal to the sum of the individual branch resistances
D.one-half the sum of the individual branch resistances -
单项选择题
Reduced voltage applied to a motor during the starting period will （）.
A.result in decreased acceleration time only
B.lower the starting current and increase accelerating time
C.cause a greater starting torque
D.increase the starting current and pump capacity -
单项选择题
Line losses in a distribution circuit are kept to a minimum by （）.
A.adding rubber insulation conductors to the circuit
B.using higher current and lower voltage increasing the
C.number of thermal relays in the circuit
D.using higher voltage and lower current
