On a transformerless inverter, the isolation detection is to protect the power stages because if any part of the array has a path to ground then a lot of current will flow when it begins bucking the HVDC to 240VAC. (It's flipping the polarity of the entire array 120 times a second) Once the inverter closes it's contactors and goes online, it's no longer isolated, so any ground faults could damage the inverter or at least trip it offline depending on the fault and how well the inverter protects itself.
The older transformer-based units usually have a 1A fuse trying one side of the array to ground. The inverter will have a circuit that checks to be sure the fuse isn't blown. If there is a ground fault in the array somewhere that exceeds 1A, then it will blow the fuse and shut everything down. On Sun, Mar 21, 2021 at 7:59 PM Robert Bruninga via EV <[email protected]> wrote: > On Sun, Mar 21, 2021 at 9:50 PM (-Phil-) via EV <[email protected]> wrote: > > > Transformerless inverters are lower cost and higher efficiency, with the > > down side that > > that must have 600V isolation. It isn't just that the iso check is > > "annoying", if there is leakage once the contactors close, it's likely > that > > you'll destroy the power stage. > > > > Helpme about isolation. My uninformed understanding about connection one > side of the array to ground was to protect/detect against frame shorts > fron putting lethal 600v onto the frame of an array. But then I noticed > the connection is made internally with a 1 amp fuse. > > So u p to 1 A at high voltage can still flow in the ground loop b efore the > detector is lost. Isnt there still potentially a lethal possibility? > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20210321/c2a51fc0/attachment.html > > > _______________________________________________ > Address messages to [email protected] > No other addresses in TO and CC fields > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/ > LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20210322/06589cc8/attachment.html> _______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/ LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
