Simultaneous trips at YWPS3 and YWPS4 on Thursday 16th October 2025

A short note on Thursday 16th October 2025 with this twinned snapshot from ez2view at 14:40 with two copies of the ‘Unit Dashboard’ widget opened up to look at both Yallourn Units 3 &4 … which we see both units tripped during the 13:35 dispatch interval (NEM time) today:

2025-10-16-at-14-40-ez2view-UnitDashboard-YWPS3and4

Note that:

  • That’s a coincident loss of almost 600MW supply, presumably at the same time (and presumably related to something happening in the substation?)
  • We see the (actual and predispatch) prices trending upwards afterwards

Here’s a quick grab from our live high(er) speed frequency monitor for the mainland, where we can see that the trip was evident in a frequency disruption (we’d need to extract the data to see more specifics):

2025-10-16-at-14-27-NEM-Mainland-Frequency

… and also noting MN129724 that relates:

‘——————————————————————-
MARKET NOTICE
——————————————————————-

From :              AEMO
To   :              NEMITWEB1
Creation Date :     16/10/2025     14:05:31

——————————————————————-

Notice ID               :         129724
Notice Type ID          :         POWER SYSTEM EVENTS
Notice Type Description :         Emergency events/conditions
Issue Date              :         16/10/2025
External Reference      :         Non-credible contingency event – VIC region – 16/10/2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE.

Non-credible contingency event – VIC region – 16/10/2025

At 1334 hrs the Yallourn unit W3 and the Yallourn unit W4 tripped.

AEMO did not instruct load shedding.

AEMO has not been advised of any disconnection of bulk electrical load.

The cause of this non credible contingency event is not known at this stage.

Manager NEM Real Time Operations

——————————————————————-
END OF REPORT
——————————————————————-’


About the Author

Paul McArdle
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.

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