Fig. 3 Fig. 4 5 high water 2 P2 ON 6 7* P2 ON 3 P2 OFF 4 1 P1 ON P1 ON 1 3 all OFF P1 OFF 2 4 Fig. 5 high water 3 OFF 2 ON 1 low water 4 dry run 5 (Ext.OFF) dry run 5 8*