The switchboards for a-csystems differ from the d-cswitch gear in that the open type panels are generally（） and the dead-front switch gear is the common rule.

Electrical supply is always needed even if only for lig...

单项选择题Electrical supply is always needed even if only for lighting so after a ship goes into service it is extremely rare for the main bus-bars to be dead, it therefore follows that the bus-bars are continuously alive（） the life of the ship.

The current flowing first in one direction and then in ...

单项选择题The current flowing first in one direction and then in another is called（） current.

Shore power must be（） during dock repair.A.disconnected...

单项选择题Shore power must be（） during dock repair.