Series QPC Quadraplex Pump Controller is used where four pumps are required to alternate to provide equal run time on each. Alternating loads allows for equal wear on all pumps lengthening their operation life. The Series QPC has five inputs allowing the four outputs to operate properly even if one of the inputs fails to open or close. Four LED indicators show the load that is energized by the SPST output contacts. The QPC is available in two sequence configurations: sequence-on-simultaneous-off (SOSO) and first-on-first-off (FOFO). In the SOSO sequence, an additional load is energized each time a higher level switch is activated, and all loads are de-energized simultaneously when the lowest level switch deactivates. In the FOFO sequence, the loads are energized in the same manner as the SOSO sequence, but loads are de-energized individually as each level switch deactivates. In either sequence, the lead load position is advanced to equalize run time on each pump. An inrush delay on both models reduces line sags by preventing multiple loads from energizing simultaneously. Please see the online service manual for more details on SOSO and FOFO sequencing.