Macao, 24 February 2011
This morning while CEM was doing a regular maintenance inspection at NAPE Substation, a high-voltage circuit breaker trip off occurred, causing a power outage at the NAPE area.
At 11:08am, when CEM had its routine maintenance inspection at NAPE Substation, a trip off occurred, causing a power outage at the NAPE area, affecting 8,000 customers, including the Landmark, Macau Science Museum, Zhu Kuan Building, Cultural Centre, Dynasty Plaza and the buildings in the NAPE area. CEM immediately activated its emergency plan. Power supply was restored for the affected customers within 4 to 14 minutes. The power supply was fully restored at 11:22am.
Since the trip-off incident caused voltage fluctuations in certain parts of the network, resulting customers in other areas also experienced a momentary power fluctuation.
The Close Ring System, which CEM invested last year to enhance the power supply stability in the NAPE area, was also affected by this incident. Even though the Close Ring system is the most advanced technology of the medium-voltage distribution system, it could not deliver its performance during this outage due to the main root cause was a high-voltage circuit breaker trip off.
CEM is highly concerned about this incident and immediately carried out investigation of the causes. Initial investigation report showed that the outage was caused by an operational fault. CEM will review the case and implement relevant measures for improvement. Moreover, CEM will submit the incident report to Energy Sector Development Office (GDSE) shortly and sincerely apologizes to the customers affected by the power outage.