<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div><br></div><div><br></div><span id="OLK_SRC_BODY_SECTION"><div style="font-family:Calibri; font-size:11pt; text-align:left; color:black; BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt"><span style="font-weight:bold">From: </span> Joshua D'Alton <<a href="mailto:joshua@railgun.com.au">joshua@railgun.com.au</a>><br><span style="font-weight:bold">Date: </span> Wednesday, 15 January 2014 9:15 pm<br><span style="font-weight:bold">To: </span> "<a href="mailto:ausnog@lists.ausnog.net">ausnog@lists.ausnog.net</a>" <<a href="mailto:ausnog@lists.ausnog.net">ausnog@lists.ausnog.net</a>><br><span style="font-weight:bold">Subject: </span> [AusNOG] DC undervoltage issues<br></div><div><br></div><div dir="ltr"><div><br></div><div>> 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.</div></div></span><div><br></div><div>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 (don’t forget we are able to pull 22MVA in each of M1 and S1 once full) we discussed and agreed these issues. NEXTDC’s philosophy was this:</div><div><br></div><div>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.</div><div><br></div><div>It’s a philosophy based around "it’s 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."</div><div><br></div><div>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 “GP" creating relationships for both organisations.</div><div><br></div><div>Cheers</div><div><br></div><div>[b]</div><span id="OLK_SRC_BODY_SECTION"><div dir="ltr"><div><br></div></div></span><span id="OLK_SRC_BODY_SECTION"><div dir="ltr"><div><br></div><div><br></div></div></span></body></html>