Logixpro Dual Compressor Exercise 2 -

Atlas roared to life. Pressure stabilized at 96 PSI. For thirty seconds, Maria breathed. Then the production line kicked into high gear—three cappers firing at once, a purge cycle on the filler, and a labeler changeover. The pressure cratered to 85 PSI.

She jumped to the control cabinet, fingers flying over the old Allen-Bradley pushbuttons. She disabled the automatic lead-lag and forced Atlas into continuous run. Then she saw the problem: Atlas’s unloader solenoid was sticky. The compressor was starting under full load, drawing 300% amperage. The thermal overload relay clicked once, twice—on the third click, it would trip.

“Atlas, you’re up,” she whispered, hammering the HMI start button.

She did the only thing left. She slammed the emergency stop on Atlas, sprinted to the auxiliary air dryer bypass valve, cracked it open to vent a tiny amount of stored air (counterintuitive, but it reduced backpressure), and then reset Atlas’s overload. logixpro dual compressor exercise 2

At 2:30, Maria Chen, the shift electrician, pulled up the LogixPro simulation on her laptop—the training software she’d mastered years ago. But this wasn’t a classroom exercise. This was Exercise 2 for real.

Maria’s mind flashed to the exercise rubric: “When a compressor faults, the alternate must take over within 2 seconds. Pressure must not fall below 80 PSI.”

Maria’s fault wasn’t random. It was molten metal and fried bearings. Atlas roared to life

In the LogixPro simulation, you had ladder logic timers: T4:0 for the “minimum run time” and T4:1 for the “anti-cycle delay.” Maria had no time to program. She had to become the PLC.

For the next forty minutes, Maria stood guard. Every 11 minutes, Atlas’s thermal overload would creep toward its limit. She’d manually cycle it off for 90 seconds—just long enough for the header tank’s stored volume to keep the line alive—then restart it. It was brutal, improvisational, and exactly like the simulation’s hardest setting: Manual Fault Recovery.

For six years, the system had run on a simple lead-lag routine: Titan ran all day, Atlas kicked in only when the pressure sagged below 95 PSI. It was dumb, but it worked. Until the heatwave. Then the production line kicked into high gear—three

Maria stared at the LogixPro window still open on her laptop. The virtual pressure gauge was steady at 95 PSI. The virtual “Dual Compressor Exercise 2” completion banner flashed green.

When the maintenance crew finally replaced Titan’s fan at 4:00 PM, Maria collapsed into a rolling chair. On the HMI, the pressure trend showed a near-perfect line at 88 PSI, with only one brief dip to 81.5 PSI.

In LogixPro’s “Dual Compressor Exercise 2,” the goal was simple: maintain 90–100 PSI with two compressors, handle duty cycling, and prevent both from running simultaneously for too long to avoid overload. The twist? A random “fault” could disable one compressor, forcing the other to handle the load within strict time limits.

Atlas groaned, then spun. The unloader, freed by the pressure relief, clicked open. The compressor started unloaded. Pressure had fallen to 82 PSI—two pounds above disaster.