[AusNOG] DC undervoltage issues

[Joshua D'Alton]

Thanks for the answers, mostly what I surmised but good to have some other
opinions.

James, so formal!  216V I saw briefly, its since increased to around 225
somewhat stable now. Across a single phase. UPS doesn't have freq
information in the GUI, I'd have to wait for the weekly report, but I
wouldn't imagine any freq changes. Power factor is also missing from the
GUI. One DC says 100% isolated 2N from supplier to rack feeds, the other
don't have the docs with me but IIRC N+1. Nothing upstream, the feeds come
into the racks into a powerbar on either side of the rack, which then the
UPS are plugged into, and then the servers into the UPSs.

Both DCs are somewhat remote, I suspect that is partly responsible. Cheers.


On Wed, Jan 15, 2014 at 10:33 PM, James Braunegg <
james.braunegg at micron21.com> wrote:

> Dear Joshua
>
>
>
> Thanks for your post, and questions regarding Datacentre voltages.
>
>
>
> What type of voltage drops are you seeing and is this across a single
> phase or three phase circuit ?
>
>
>
> Have you notice the Hz frequency change, and are you monitoring power
> factor ?
>
>
>
> What is upstream from the power within your rack ?
>
>
>
> Whilst you might have A and B power feeds it  could be supplied via a STS
> (static transfer switch) via a N+1 (x) UPS deployment or is it a 2N UPS
> setup where both feed A and feed B are 100% isolated.
>
>
>
> Most if not all double conversion battery based UPS’s will have phase
> voltage monitoring and below “x” threshold on any incoming phase from its
> upstream power source will transfer load to say batteries to remove any
> issues with zero interruption.
>
>
>
> Upstream from the UPS infrastructure will be ATSs which also will have
> phase voltage monitoring and below “x” threshold on any phase from the
> incoming supply will trigger the ATS to obtain power from its alternative
> source typically diesel generation power.
>
>
>
> As for power problems within Victoria I have not seen any issues with our
> mains supply its been perfect, nor noticed any issues at our pop sites.
>
>
>
> Kindest Regards
>
>
>
>
>
>
> *James Braunegg**P:*  1300 769 972  |  *M:*  0488 997 207 |  *D:*  (03)
> 9751 7616
>
> *E:*   james.braunegg at micron21.com  |  *ABN:*  12 109 977 666
> *W:*  www.micron21.com/ip-transit   *T:* @micron21
>
>
>
>
> [image: Description: Description: Description: Description: M21.jpg]
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> *From:* AusNOG [mailto:ausnog-bounces at lists.ausnog.net] *On Behalf Of *Joshua
> D'Alton
> *Sent:* Wednesday, January 15, 2014 10:15 PM
>
> *To:* AusNOG at lists.ausnog.net
> *Subject:* [AusNOG] DC undervoltage issues
>
>
>
> Evening noggers, hope you're all surviving the heat, especially in VIC!
>
>
>
> Speaking of, in 2 DCs were seeing borderline undervoltage on our UPSs (yes
> we run them even with A+B power because sensitive equipment), I've read
> that there are power issues in VIC at the moment, but I thought they were
> limited to residential zones (with rolling black/brownouts)?
>
>
>
> Anyone else seeing this, or have comments?
>
>
>
> As a side question, does anyone (perhaps Bevan?) know if DCs will manually
> switch to genny/backup power in this sort of scenario, if so details would
> be nice.
>
>
>
> (with regards to that, I looked at one DC contract and it doesn't mention
> anything about the specifics of power delivered, just that it is A+B with X
> battery backup and Y generator capacity, and Z SLA, doesn't mention what
> sorts of voltages would break said SLA...)
>
>
>
> Anyhoo, cheers!
>
>
>
> PS, also seeing strange intermittent issues with Telstra and Pacnet
> connecting to local google and others, not sure why the power quality would
> affect that, but..
>
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