Value chain · CLM-1210
In plain terms
Britain's grid runs at 50 Hz, normally kept between 49.5 and 50.5 Hz. A power station connected to it, which would include a rectenna, must keep running between 49 and 51 Hz without limit, and for set minimum times further out, down to 47 Hz and up to 52 Hz.
The claim as recorded
The GB Grid Code (Issue 6 Rev 41, ECC.6.1.2.1) states that the transmission system frequency "shall be nominally 50Hz and shall be controlled within the limits of 49.5 - 50.5Hz unless exceptional circumstances prevail", and that it "could rise to 52Hz or fall to 47Hz in exceptional circumstances". A connected user's plant must be designed to operate continuously from 49.0 to 51 Hz; for at least 90 minutes each time the frequency is above 51 Hz (to 51.5 Hz) or below 49.0 Hz (to 47.5 Hz); for at least 15 minutes each time it is above 51.5 Hz (to 52 Hz); and for at least 20 seconds each time it is below 47.5 Hz (to 47 Hz). Disconnection by frequency or speed relays "is not permitted within the Frequency range 47.5Hz to 51.5Hz".
Evidence behind this: T1, the Grid Code Connection Conditions for EU Code Users read directly.
Scope and limits
The table in ECC.6.1.2.1.2 is for EU Code Users' Plant and Apparatus; HVDC Systems and Remote End HVDC Converter Stations have their own table (ECC.6.1.2.2, PDF 200-201) with different minimum times; DC Connected Power Park Modules have their own table (ECC.6.1.2.3, PDF 201) with the same times. Wider ranges can be agreed (ECC.6.1.2.1.4). Combined voltage and frequency ranges are in ECC.6.3.12 and ECC.6.3.13, not read here. Revision 41 text; later packs should be checked before publication.
What it assumes
That a rectenna plant would connect as a Power Park Module under the ECCs, as other converter-connected plant does; no text read classes it.
Where it comes from
PDF 200, printed ECC p.8 of 143, verbatim: "The Frequency of the National Electricity Transmission System shall be nominally 50Hz and shall be controlled within the limits of 49.5 - 50.5Hz unless exceptional circumstances prevail". Same page: "The System Frequency could rise to 52Hz or fall to 47Hz in exceptional circumstances." Same page, the table: "Operation for a period of at least 15 minutes is required each time the Frequency is above 51.5Hz."; "Operation for a period of at least 90 minutes is required each time the Frequency is above 51Hz."; "49.0Hz - 51Hz Continuous operation is required"; "Operation for a period of at least 90 minutes is required each time the Frequency is below 49.0Hz."; "Operation for a period of at least 20 seconds is required each time the Frequency is below 47.5Hz." ECC.6.1.2.1.3: "disconnection, by Frequency or speed based relays is not permitted within the Frequency range 47.5Hz to 51.5Hz".
Basis: Grid Code Issue 6 Revision 41, ECC.6.1.2.1, as in force 5 June 2026
Cite this
energyaperture.com/c/clm-1210
CLM-1210, Energy Aperture, as of 2026-06-05.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-452
- CLM-1107The actual Grid Code figure is not a flat 0.95 power factor at all voltages: the plant must push reactive power out when the grid voltage...CLM-1108After 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...CLM-1109The rulebook says the same as the guidance: nobody has to make their inverters behave like a rotating machine, but the grid needs enough...CLM-1211Britain's main transmission grid runs at 400 kV and 275 kV, and parts of the 132 kV network in Scotland. On the 400 kV network the voltage...