Although your ass has been kicked for quite sometime on this job, you’re still at it, so congrats on that.
Since these 6 units-two different groups shut down always on Monday early in the morning, these units are down until reset, or all 6 mysteriously recover on their own.
Any possibility you can have the building engineer (or yourself $$$) visit the site late Sunday and just key them down on Fire Recall (both groups), leave them and you’ll return Monday as usual and see if the cars are faulted with the same fault? I mean, they’re down anyways right?
Does the CPU on these units utilize a 5v supply or is it 24v?
And does the fault description “current mains differential” have anything to do with incoming power phasing?
Do the CPU’s give more info on what happened when it happened? All I would want to know is if all units were idle when the command came to shutdown. I’m hoping yours were and you can prove it.
Typically early morning hours is when chillers, boilers or large cooling systems are brought up online for the day.
If all drives fault the same when indeed they’ve been keyed onto Fire Phase 1 Recall (zero motion), I’d be inclined to point at incoming power and the drives detected the same incoming power issue in both groups. ***Both groups are in the same building?
