A device used to interrupt or break an electrical circuit when an overload condition exists; usually installed in the positive circuit; used to protect electrical equipment.
单位能量输入所提供的能量量或有用能量. 通常用于照明系统, w在这里 the visible light output of a luminary is relative to power input; expressed in lumens per Watt; the higher the efficacy value, 能源效率越高.