Hong Kong government urges power companies to improve systems following outage incident


7th June 2023 – (Hong Kong) The Hong Kong government has called on the city’s two power companies to improve their systems in the wake of an outage incident that left some areas on Hong Kong Island without power on 19th April, 2023. This came in response to a question raised by Hon Chan Hok-fung in the Legislative Council on 7th June.

According to the Incident Investigation Report submitted by the Hongkong Electric Company Limited (HEC) to the Electrical and Mechanical Services Department, the outage was caused by a short circuit resulting from an engineer’s mistake in energising a spare cable. The report revealed that the incident was related to the failure to update the circuit diagrams of the Energy Management System of the Cyberport 275-kV Switching Station in a timely manner.

In response to the incident, the government has requested HEC to conduct an in-depth investigation into the cause of the incident and has been monitoring the implementation of remedial measures. The government is currently examining the investigation report with the assistance of an independent third-party expert to assess whether the identified cause is well-founded and whether the rectification measures are appropriate. The government has also urged HEC to implement improvement measures to prevent similar incidents from happening again.

Regarding Hon Chan Hok-fung’s questions, the government provided the following replies:

(1) The table at Annex provides the whole-year figures and details of the incidents causing power interruption of the two power companies since the current Scheme of Control Agreements came into effect in late 2018/early 2019.

(2) When there is an electrical fault in the power system, the electrical protection system operates automatically to isolate the faulted equipment, so as to reduce the impact on the power system. If a power interruption is caused by an electrical fault, the operator of the system control centre first has to confirm and verify the status of the system and the concerned faulted equipment, and then manually carries out power supply restoration work by remote control at a suitable time. Under some special circumstances, the power companies also adopt automatic power supply restoration systems.

(3) The two power companies are obliged to timely update the relevant drawings with regard to any changes on the power supply systems, including commissioning of new equipment or retirement of old equipment. The investigation report of the power supply incident in some areas on Hong Kong Island on 19th April submitted by HEC to the Director revealed inadequacies in the management of the drawings. HEC is now obliged to formulate improvement measures, including establishing guidelines on updating detailed transmission schematic drawings, single-line diagrams and circuit diagrams of energy management systems, as well as their respective methods of use and limitations, etc.

The Hong Kong government has emphasised the importance of ensuring the safety and reliability of the city’s power supply systems. The government will continue to closely monitor the implementation of improvement measures by the power companies to prevent similar incidents from happening in the future.