My home’s PQube 3 detected a frequency violation (as low as 49.20Hz) at 4:17PM.
Note: Trigger threshold was set at 49.75Hz. Hence don’t be too alarmed with the duration of 3005 seconds.
Nominal system frequency for Singapore is +/-1% of 50Hz (49.5Hz – 50.5Hz)
Time-line wise, it generally matched the power outage that affected parts of Malaysia’s Klang Valley and Johor Bahru (due to an incident at a power plant in Melaka), as reported by AsiaOne and The EdgeMalaysia.
“The outage at Edra Melaka Power Plant, owned by independent power producer Edra Power Holdings Sdn Bhd, took out supply capacity equivalent to over 10% of Peninsular Malaysia’s maximum electricity demand and resulted in blackouts across Kepong, Kuala Lumpur and Johor Bahru for more than an hour” – TheEdgeMalaysia
Singapore is connected to Peninsular Malaysia at 230kV.
https://www.asiaone.com/malaysia/johor-klang-valley-blackout-power-outage-tnb-oct-15