It indicates the battery terminal voltage when the overdischarge protection started and the fire emergency luminaries can't play the role of emergency. 过放电保护部分启动，消防应急灯具不再起应急作用时电池的端电压。
Many kinds of emergency lighting fixtures are available such as reflecting lamp trays for fluorescent lamps, brackets, ceiling lamps and recessed light fixtures. 应急灯具备有荧光灯发射灯盘，支架，吸顶灯，筒灯等系列。
