HI all - long time lurker, first time poster (lots of collective knowledge around here - such a helpful community!), and hoping to get some feedback on a recent PV issue we've seen at one of our sites.
A PV array is installed on a premises, and feeds into the utility via a net meter.
The utility recently dropped a leg of power, but the inverter failed to shut down and a transformer between the inverter and distribution gear got burnt up.
The utility transformer is a Delta-Wye (208/120, 3P, 4W on the secondary) which feeds the buildings main distribution gear. The PV array is 480V off the inverter, which feeds into a Wye-Delta (Primary/High-side: 480V Wye, no neutral, Secondary/Low-side: 208V Delta, feeding the distribution gear).
The relationship between the Wye/Delta configurations is getting me a little confused; when the utility dropped a phase, could that cause an amperage spike in the two "live" legs and cause the PV transformer failure? I also understand that it can be a little tricky for an inverter to sense a dropped phase from the utility - is that accurate?
Thanks in advance for any feedback.
A PV array is installed on a premises, and feeds into the utility via a net meter.
The utility recently dropped a leg of power, but the inverter failed to shut down and a transformer between the inverter and distribution gear got burnt up.
The utility transformer is a Delta-Wye (208/120, 3P, 4W on the secondary) which feeds the buildings main distribution gear. The PV array is 480V off the inverter, which feeds into a Wye-Delta (Primary/High-side: 480V Wye, no neutral, Secondary/Low-side: 208V Delta, feeding the distribution gear).
The relationship between the Wye/Delta configurations is getting me a little confused; when the utility dropped a phase, could that cause an amperage spike in the two "live" legs and cause the PV transformer failure? I also understand that it can be a little tricky for an inverter to sense a dropped phase from the utility - is that accurate?
Thanks in advance for any feedback.