For ballasts with rest mode facility changeover from rest mode to normal mode shall occur automatically at greater than 0 . 9 times the off cycle extended to 3 s and the ballast put into the rest mode after 2 s of the off periods in the 500 switching cycles 带有休止状态装置的自容式应急灯具,从休止向正常状态的转换应在不大于0 . 9倍额定电压下自动运行3秒,在500次开关周期结束切断电源的2秒时间内应使自容式灯具进入休止状态。