[AusNOG] DC undervoltage issues

[Tony de Francesco]

Another thing to consider: if the DC cooling system is served by air-cooled
DX CRAC units or air-cooled chillers, the power draw of the cooling system
on a day like today would be at its absolute peak. Such an event will place
additional current draw on the main power feed to the site and potentially
drop site voltage.

However, if a double conversion static UPS system is in place and operating
without fault then you should not be seeing a voltage drop.

Regards

Tony de Francesco
Technical Director
P.U.E. Pty Ltd
Mob: +61 (0) 457 701 179
Email: tonyd at pue.com.au
On 15/01/2014 10:35 PM, "Tony de Francesco" <tonyd at pue.com.au> wrote:

> joshua,
>
> Undervoltage at the street mains supply to the DC would probably be the
> result of excessive power draw on the main electrical grid.
>
> However, if a double conversion static UPS system is used as the main DC
> UPS, the A+B supply voltage should remain at a very stable 240V AC.
>
> Many new UPS systems are designed for lower losses and deliver power
> straight through with some minor voltage regulation  (known as line
> intetactive UPS).
>
> It could bd possible that the DCs main UPS is in bypass mode (due to a
> fault or maintenance) in which case you would bd seeing the street voltage.
>
> Another less likely possibility is that current draw within the DC is at a
> peak and cresting excessive voltage drops.
>
> Regards
>
> Tony de Francesco
> Technical Director
> P.U.E. Pty Ltd
> Mob: +61 (0) 457 701 179
> Email: tonyd at pue.com.au
> On 15/01/2014 10:15 PM, "Joshua D'Alton" <joshua at railgun.com.au> wrote:
>
>> 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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>>
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