Regarding VA/W conversion, keep in mind the power crest factor, and that it is not always sqrt(2)/2 =~0.7
Some devices actually report theirs and I've seen the likes of 0.9 for example. On Mon, Mar 21, 2022, 14:36 Greg Troxel <[email protected]> wrote: > > [I was going to rely privately to reduce list traffic, but the list > instructed me not to do that :-( ] > > Charles Lepple <[email protected]> writes: > > > On Mar 17, 2022, at 7:26 PM, Greg Troxel <[email protected]> wrote: > >> > >> My script is in the process of being extended to also deal with apcupsd > >> and that seems to have different variables, like timeleft in minutes > >> instead of runtime in seconds. It seems obvious to me that I should > >> bring things into a common schema, because the monitoring system doesn't > >> care about UPS brand; it wants to know is utility power good enough, how > >> many seconds left, etc. > > > > I am not necessarily recommending that you should use apcupsd-ups > > (it's monitor-only and won't send the shutdown command[*], for one > > thing); however, it's worth pointing out that a few of the conversion > > factors are documented in that driver's source: > > > > > https://github.com/networkupstools/nut/blob/v2.7.4/drivers/apcupsd-ups.h#L66 > > > > [*] https://networkupstools.org/docs/man/apcupsd-ups.html#_limitations > > Thanks, that was useful. The case that prompted me to ask was a UPS run > by someone else that I think is using apcupsd and not nut. I'm not > responsible for the UPS; I just want to get power status. > > >> I wonder how much NUT does that by itself, or if it's more doing format > >> translation of the individual units. And I would appreciate comments on > >> the wisdom/necessity of this approach. > > > > What Jim said about this is technically correct, but I would look at it > another way: > > > > NUT defines standard units for variables (as long as the variables are > > not marked as "opaque"), and the drivers map device-specific readings > > to those standard units. (USB HID PDC tends to use seconds, as do most > > SNMP MIBs, if I am not mistaken.) > > > > Units are in parentheses in the Description column: > https://networkupstools.org/docs/user-manual.chunked/apcs02.html > > Thanks. So most of what I was asking about is defined: there are a list > of NUT variables, defined semantics, and units. > > The thing that's messy is power vs realpower (which is a bit funny > because they are "apparent power" and "power"). It seems old Best units > report in VA and some APC in W. Whether to map them both into > "power-ish" for the mqtt protocol is an interesting question, especially > since I don't really believe either measurement without confirming it. > > > To the extent my script supports apcupsd, it would make sense to do the > same normalization. > _______________________________________________ > Nut-upsuser mailing list > [email protected] > https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser >
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