... min. ( on/off frequency is 50 operations/min)RL8 series:Electrical life (resistive load): 300,000 operations min.(rated load ... ( on/off frequency is 120 operations/min)4.Purpose:RL7 Series:Food machinery, auto packing machines, machine tool, conveying machinery, ... machinery which need the strict protect and so on.RL8 series:Ideal for general plant facilities: engineering machinery,conveyer machinery, ...