單項(xiàng)選擇題

The operator of electrical motors should keep a constant check on the loads they carry because （）

A.low loads necessitate frequent insulation cleaning
B.exceeding nameplate values shortens useful life
C.energy is wasted if full loading is not utilized
D.power factor correction methods are load dependent

你可能感興趣的試題

單項(xiàng)選擇題

Which of the listed sections of an emergency switchboard is used to supply power for alarm signals under emergency conditions?（）

A.The generator and bus transfer section
B.The 450 volt, 60 cycle, 3 phase bus
C.The 120 volt, 3 phase, 60 cycle bus
D.The 24 volt DC bus

單項(xiàng)選擇題

When the current in a power transmission line is increased, the power loss （）

A.increases as the square of the current
B.decreases as the square root of the current
C.remains the same, as it is independent of current flow
D.increases in direct proportion as the current