[AusNOG] DC undervoltage issues

[Bevan Slattery]

From:  Joshua D'Alton <joshua at railgun.com.au>
Date:  Wednesday, 15 January 2014 9:15 pm
To:  "ausnog at lists.ausnog.net" <ausnog at lists.ausnog.net>
Subject:  [AusNOG] DC undervoltage issues


> 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.

Side answer:  It depends on the size of the power draw, the State, the
thinking of the DC operator and the relationship with the energy provider.
However I can remember when we negotiated power access with the various
energy providers (don¹t forget we are able to pull 22MVA in each of M1 and
S1 once full) we discussed and agreed these issues.  NEXTDC¹s philosophy was
this:

If the network grid was deemed to be becoming unstable (at or approaching
capacity) either by NEXTDC or the energy provider then NEXTDC had the
ability to activate their DRUPS engines to take load off the grid.  This
could be done engine-by-engine over a period of time to ensure a very smooth
and graceful transition from:to the grid.  Also remember NEXTDC operates
DRUPS/power bridges via an ISO Parallel Bus.  Regardless the DRUPS are
independently looking at voltage and frequency changes and are preconfigured
to kick in the engine if the network was outside of tolerance in the absence
of an outage.

It¹s a philosophy based around "it¹s better to exit the grid gracefully and
sit on secure supply (internal) and let the grid get some capacity and
stability rather than sit on the grid, stress it and risk it falling in a
heap and slamming across at a time and manner determined by the breaking
point of the electricity network already under stress."

It pays to have an excellent relationship with the energy supplier and be in
direct contact with the transmission engineering team which I know the
NEXTDC team has.  I also know that Global Switch did too.  That comes from
having ³GP" creating relationships for both organisations.

Cheers

[b]





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