I have a problem in a 10 floor building. When we operate with the power electricity supplier, the elevators (02 units) operate correctly with no problem, if the power supplier fails then the electric generator (101 kw) gets to work automatically, but then the elevators start to fail. They suddenly stop in any direction, going up or down, they reset automatically and if you are inside one of them you have to push again the button for the desire floor with the inconvenience that it can stop again. The system is 120/208Y.
I have checked voltage, it is ok, power factor is ok, the logic of grounding is ok, apparently everything is in it's place. As I said, the elevators work properly with the power electricity supplier, the problems appear when we are working with the electric generator plant.
The circuit for the elevators is wired with aluminium 8,000 series XHHW-2 250MCM for a panelboard that supplies energy for a 10hp and 15hp elevators.