Mainland frequency drop with Loy Yang A1 trip on Saturday evening 30th August 2025

I’d been in the process of looking in more detail at the ‘’, and noticed on Saturday evening 30th August 2025 this trip (and then subsequent recovery) of the Loy Yang A1 unit – seen here in the successive ‘Notifications’ widget alerts from ez2view:

As we can see here, the unit tripped from 505MW in the 5-minute period to 19:26 NEM time on Saturday evening – so it was a pretty simple matter to extract the following 3-hour time-series of one of our (Brisbane-based) measurement points for mainland frequency:

We can see that the lowest point (in the 3-hours sampled) was was 49.873Hz  at 19:22:29.1 on Saturday 30th August 2025 – which:

1)  Was a rapid drop:

(a)  From 50.010Hz  at 19:22:24.9;

(b)  So down 0.137Hz in 4.2 seconds (-0.0326Hz/sec)

2)  But remained within the Normal Operating Frequency Band (NOFB).