I’ve taken the opportunity of a quiet space to extract some data over a 4-hour time range (and at 0.1 second cadence) to compile the following trend:
Unfortunately:
our ‘Device 2’ location was temporarily offline (following some power outages following Brisbane storms at the time)
so we had to revert back to the new ‘Device 1’ location … which (as noted on the image) we have observed appears to suffer from occasional noise (perhaps related to local intermittent power quality issues?).
So in the chart above we can’t really trust the specific details of the depth of the frequency drop, other than to note that the low point will have been around ~17:01 (NEM time) on Thursday 30th October 2025.
That should be enough for us to explore in a bit more detail….
Paul was one of the founders of Global-Roam in February 2000. He is currently the CEO of the company and the principal author of WattClarity. Writing for WattClarity has become a natural extension of his work in understanding the electricity market, enabling him to lead the team in developing better software for clients.
Before co-founding the company, Paul worked as a Mechanical Engineer for the Queensland Electricity Commission in the early 1990s. He also gained international experience in Japan, the United States, Canada, the UK, and Argentina as part of his ES Cornwall Memorial Scholarship.
The (concerning) frequency spike across the NEM in the middle of the day (Tuesday 19th August 2025) has triggered many proximate questions – understandable – but also has raised these 3 Broader Questions.
A short article to flag a two rapid (and noticeable) fluctuations in Mainland Frequency that we spotted this afternoon/evening on Tuesday 29th October 2024.
With respect to the ~17:00 period on Thursday 30th October 2025 (and the frequency drop, possibly outside the NOFB), we take a look at the Dispatch Error of individual Semi-Scheduled units to find patterns.
1 Commenton "A second look at the frequency drop on Thursday evening 30th October 2025"
Here’s the raw hz data from Melbourne. 49.84hz is the lowest I saw
https://www.dropbox.com/scl/fi/x1t4c6wku2fw6dt21c2m0/hz-data.csv?rlkey=vz5w7ppo8m8umf1md09jrelxw&dl=0 (note it also has noise but