。L-0V起了L-5V与L-24V交替的标识作用。此时完成对一个回路点的巡检，巡遍一百九十点，则完成一个回路的巡检。-. L-0V from the L-5V and L-24V marking the turn of the role. At this point the completion of a loop point inspection, visited 190 points, then completed a circuit of inspection.