Genset Reverse Power Alarm

[bpk]

I have a facility where the Genset failed to run with a Reverse Power Warning Alarm. The Genset itself is 1998 model, but newer CAT controls retrofitted within the last year. It is the only genset on the property.
Is it even possible for this alarm to be legitimate being the solo generator? The building has a couple IT Server rooms with UPS backed up equipment, I'm leaning towards one of them back feeding somehow and being seen by a transfer switch ?
Just trying to get any ideas before digging in, want to be sure I've ruled out other possibilities before calling the Generator Technician company. Thanks in advance

 

[ATSman]

If the rev pwr alarm is being seen by the gen controls then it cannot be seen by controls in an ATS. An ATS does not have the logic to make that determination. And if there is only 1 gen (no paralleling) then the rev pwr condition of opposing currents do not apply. If the system was operating properly before the CAT modification then chances are (and I would bet you lunch on it!) there may be miswiring by whoever did the mod. The next logical step would be to call in the vendor who did the mod to check his wiring. Which leads to the question: was the system tested after the mod was performed?

 

[hillbilly1]

Did this happen during an exercise cycle? I’ve witnessed several stores with backfeed from utility because circuits from normal (non backed up panels) and emergency panels were tied together in the fixtures. Because they were on the same phase, nothing happened until utility was lost, and those circuits were trying to power the normal panel back up via generator. Usually while utility is lost, the backfeed is short lived because the breakers would trip on over current.

 

[ron]

Is the ATS an open or closed transition transfer? I will continue guessing open transition.
Do they have any large motors at the facility (chiller, elevator, etc) that start/stop with an across the line starter.
If so, I would put the building on gen, and see if stopping the motor may regen enough power into the system to cause the gen to try to absorb it and cause the reverse power alarm.