The SGX speaks up: What caused yesterday’s power outage?

The culprit comes as a surprise.

The Singapore Exchange’s uninterruptible power supply (UPS) systems failed to live up to their name and caused yesterday’s power outage, the SGX reported today.

The SGX data centre’s two UPS systems rely on power from two substations. Each UPS system also has its own internal power source, creating four layers of redundancy which should have been enough to prevent yesterday’s power outage.

When supply fluctuated yesterday at the substations, the UPS systems switched to their internal power source. The outage occurred after the internal power source in both UPS systems malfunctioned.

“This malfunction affected the hardware providing market participants’ connectivity to SGX’s markets. Market participants were disconnected at 1418 hours and SGX declared a formal trading halt at 1451 hours. No trades were executed between 1418 hours and 1451 hours,” stated the SGX.

The Securities market participants were able to re-connect starting at 4:45 pm followed by a pre-opening session at 5:00 pm, and the market reopened for trading at 5:15 pm. 

Trading was extended beyond the normal trading hours to provide for the required minimum of 30 minutes of continuous trading. Securities market pre-closing session started at 5:45 hours and the market closed at 5:51 hours.

The Derivatives market participants were able to re-connect from 6:00 pm followed by a pre-opening session at 6:45 pm, and the market reopened for trading at 7:00 pm. 

The SGX said in a statements that further tests have been successfully carried out overnight, and contingency measures have been put in place to reduce the recovery times should there be a repeat of the UPS system malfunction.

“The power supply disruption was transient in nature, bringing about a potential mismatch between the primary and secondary market order books. As such, a cut-over to the secondary data centre from the primary data centre was not executed. A complete restart of both primary and secondary systems was necessary. This step was essential to ensure continued integrity of the markets. This recovery process was completed at 1645 hours for the securities market and 1800 hours for the derivatives market,” stated the SGX.