Value chain · CLM-1108
In plain terms
After the first 140 milliseconds, the rule is a line on a chart: the lower the grid voltage sags, the shorter the time the plant must hold on, from 0.14 seconds near a full collapse out to three minutes at a 15 per cent sag. Then it has to be back to 90 per cent output within a second of the voltage recovering, and stay on for half an hour.
The claim as recorded
Beyond the 140 ms zero-volt case, a Type C or Type D Power Park Module must stay connected for any balanced Supergrid voltage dip on or above Figure ECC.6.3.15.9(b): 15 per cent retained voltage at 0.14 s, rising linearly to 80 per cent at 1.2 s, 80 per cent to 2.5 s, 85 per cent to 3 minutes and 90 per cent thereafter, so the longest dip the code requires it to ride through is 3 minutes at 85 per cent of nominal (or 2.5 s at 80 per cent); it must restore active power to at least 90 per cent of the pre-dip level within 1 second of the voltage returning to 0.9 pu, and remain connected and stable for up to 30 minutes afterwards. The requirements do not apply below 5 per cent of Rated MW.
Evidence behind this: T1-the code's own voltage-duration line for Power Park Modules, read from the figure.
Scope and limits
The figure is marked "NOT TO SCALE" (a render reading; the words are not in the text layer) on its synchronous twin (p.255) and drawn with a broken time axis; the vertex values are printed, so nothing is read by eye. The recovery duty has an exception where the "Intermittent Power Source" has itself reduced during the dip. The 140 ms case (ECC.6.3.15.8) is CLM-0789's and is not restated here.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.256, normalised: "remain transiently stable and connected to the System without tripping of any OTSDUW Plant and Apparatus, or Power Park Module and / or any constituent Power Park Unit, for balanced Supergrid Voltage dips and associated durations on the Onshore Transmission System"; raw: "anywhere on or above the heavy black line shown in Figure ECC.6.3.15.9(b)". Figure from crop p0256-fig-ecc-6-3-15-9b-frt-ppm.png: y "Supergrid Voltage Level (% of Nominal)" 15, 80, 85, 90; x "Supergrid Voltage Duration" 0.14s, 1.2s, 2.5s, 3 minutes. p.257, normalised: "within 1 second of restoration of the voltage to 0.9 pu of the nominal voltage"; raw: "to at least 90% of the level available immediately before the occurrence of the dip"; normalised: "For up to 30 minutes following such a Supergrid Voltage dip on the Onshore Transmission System each Power Park Module and / or any constituent Power Park Unit and OTSDUW Plant and Apparatus is required to remain connected and stable provided System operating conditions have returned within those specified in ECC.6.1"; "do not apply when the Power Park Module (excluding Non-Synchronous Electricity Storage Modules) is operating at less than 5% of its Rated MW".
Basis: per cent of nominal Supergrid voltage against dip duration
Related records
- Answers question
- QST-012 not published in this release
Cite this
energyaperture.com/c/clm-1108
CLM-1108, Energy Aperture, as of 2026-06.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-452
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