ARM Series Alternating Triplex Quadraplex Controllers

ARM Series Alternating Triplex Quadraplex Controllers from the ATC Diversified Electronics division of Marsh Bellofram is a family of rugged, high-reliability alternating relays and triplex and quadraplex controllers, designed to ensure equal runtime of multiple load installations in pump sequencing, level control, lift station, motor protection and other industrial applications. The series incorporates a microprocessor-based controller which evenly distributes runtime by automatically alternating designated lead and lag loads between multiple pump sequences.

These triplex and quadraplex controllers are available with either Sequence-On-Simultaneous-Off (SOSO) or First-On-First-Off (FOFO) output logic. The special function models are differentiated by a rotary switch that allows any output to be locked as the lead load or any one load to be omitted while sequencing only the remaining loads. In addition to load omission and lead selection, the expandable model can be set for 2, 3, or 4 load operation with either SOSO or FOFO logic. All models feature intrinsically safe inputs and logic that allows the outputs to operate properly even if one of the inputs fails to open or close. For example: if the off switch fails to close, the lead load will not energize until both the lead and the lag switches close. An inrush delay on all ARM Series Alternating Triplex Quadraplex Controllers models reduces line sags by preventing multiple loads from energizing simultaneously.



  • Three and four load output models
  • Intrinsically safe inputs
  • FIFO & SOSO versions
  • Optional omit/lead selection switch
  • UL913 listed device


  • Pump sequencing
  • Level control
  • Lift stations
  • Motor protection
  • Other industrial applications