Lift Station — Alternating Pumps

Briefing

A wet-well lift station uses two submersible pumps in alternating duty. When the wet well rises to the HIGH level, the duty pump starts; it stops when the well drains to LOW. After each completed cycle the duty assignment swaps so both pumps accumulate equal runtime. A thermal trip on the duty pump hands control to the standby pump. If both thermals trip simultaneously, or the well overflows (above HIGH for too long without draining), the ALARM_HORN and ALARM_LAMP activate.

Objectives

• WET_WELL_HIGH starts the duty pump; WET_WELL_LOW stops it
• Duty alternates after each completed pump cycle (HIGH → LOW)
• PUMP1_THERMAL trips Pump 1 — standby Pump 2 takes over immediately
• PUMP2_THERMAL trips Pump 2 — standby Pump 1 takes over immediately
• Both thermals tripped simultaneously triggers ALARM_LAMP and ALARM_HORN
• Tank overflow (level stays at HIGH with no working pump) triggers ALARM_LAMP and ALARM_HORN

I/O Table

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

1. #1Pump 1 (duty) starts on WET_WELL_HIGH

   With no thermals tripped, Pump 1 starts when level rises to HIGH

2. #2Duty pump stops on WET_WELL_LOW

   Pump 1 stops when level drains to LOW

3. #3Duty alternates after each fill cycle

   After one complete cycle Pump 2 becomes duty

4. #4Pump 1 thermal trip hands off to Pump 2

   PUMP1_THERMAL while Pump 1 is duty causes Pump 2 to start

5. #5Both thermal trips activate alarm

   PUMP1_THERMAL AND PUMP2_THERMAL triggers ALARM_LAMP and ALARM_HORN