Hey Arjen,<br><br>hope you're doing fine.<br><br><div class="gmail_quote">2011/4/16 Arjen de Korte <span dir="ltr"><<a href="mailto:nut%2Bdevel@de-korte.org">nut+devel@de-korte.org</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Citeren Arnaud Quette <<a href="mailto:aquette.dev@gmail.com" target="_blank">aquette.dev@gmail.com</a>>:<div class="im"><br>
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we (Eaton) have created a new data to expose efficiency of the UPS<br>
(basically it is the ratio of the output current on the input current).<br>
I know that at least APC should also provide it on some units, since I've<br>
seen evidence in an EPA presentation [1].<br>
<br>
So I'd like to create the following new data:<br>
<br>
- Name: ups.efficiency<br>
- Description: Efficiency of the UPS (ratio of the output current on the<br>
input current) (percent)<br>
- Example value: 99<br>
<br>
As usual, comments and feedback are very welcome...<br>
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Two comments:<br>
<br>
1) What would be reported if the UPS is running on battery? There clearly would be no input power at that time. What is reported in that case?<br></blockquote><div><br>in Eaton implementation, switching to battery gives an "ups.efficiency = 0"<br>
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2) Calculating the efficiency based on the ratio of input and output *current* leaves a giant loophole to artificially increase the reported efficiency. On an online UPS one could increase the 'efficiency' by setting the output voltage a few percent above the input voltage. Similarly, if a system would have a near unity power factor on the input, but a crappy one on the output, you'd also inflate the reported efficiency by using the RMS figures.<br>
</blockquote><div><br>indeed. and that's what we'll get if marketing takes over engineering.<br>note that the standard disclaimer on device's data applies: this is not a lab measurements tool. Data are only approximations...<br>
<br>as for Eaton implementation, I don't have the exact formula used in Eaton devices, but this is an approximation that also takes in account some percentage loss.<br>As an example, here is a data excerpt of what I have with a unit here:<br>
(...)<br>ups.efficiency: 72<br>ups.load: 13<br>ups.power: 209<br>ups.power.nominal: 1500<br>ups.realpower: 108<br>ups.realpower.nominal: 1350<br>ups.type: offline / line interactive<br>(...)<br><br>note that this unit is a line interactive.<br>
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I'd only see some merit in reporting this, if it would be the ratio of input and output real power values. I would be surprised if in a real world scenario however if one would get very close to 99% (if not in running in bypass mode). A more typical value of a double conversion UPS would be something between 90-95% and even then only when the UPS is properly scaled for the designed load. The good thing would be that people might be made aware how much power they are wasting, given that fact that in many cases a UPS will not be operated near the optimum efficieny load.<br clear="all">
</blockquote></div><br>indeed. I at least consider this as a first step in the right direction.<br>And it's also true that the example value may seem like a troll (putting something like 92 % would probably be more suitable).<br>
As for a 99 % efficiency, apart from running on bypass, I only know units like Eaton 9395, that have internal modules powered up or down depending on the ups load.<br>which helps a lot in improving efficiency.<br><br>cheers,<br>
Arnaud<br>-- <br>Linux / Unix Expert R&D - Eaton - <a href="http://powerquality.eaton.com" target="_blank">http://powerquality.eaton.com</a><br>Network UPS Tools (NUT) Project Leader - <a href="http://www.networkupstools.org/" target="_blank">http://www.networkupstools.org/</a><br>
Debian Developer - <a href="http://www.debian.org" target="_blank">http://www.debian.org</a><br>Free Software Developer - <a href="http://arnaud.quette.free.fr/" target="_blank">http://arnaud.quette.free.fr/</a><br><br>