[AusNOG] DC undervoltage issues

[James Braunegg]

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
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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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