Sri Lanka (CEB) ride-through requirements
Low-voltage ride-through, Frequency ride-through for Sri Lanka. Every breakpoint below is read from the code itself, and where a point was taken off a published figure rather than stated in the clause, the section under that chart says so — an envelope that stops where its published chart stops.
What is the low-voltage ride-through envelope for Sri Lanka (CEB)?
The plant must ride through for any voltage that stays on or above this envelope. The envelope holds 0 pu from t = 0 to 140 ms; then ramps linearly from 0 pu at 140 ms to 0.8 pu at 1.2 s; then 0.8 pu from 1.2 s to 2.5 s; then 0.85 pu from 2.5 s to 3 min; then 0.9 pu from 3 min, plotted to 10 min.
The clause states this boundary as a line; intermediate points are interpolated between its stated vertices. The envelope stops where the published chart stops; the code states no end time.
Applies to Generators connecting to the CEB transmission grid
| From | To | Voltage | Between the points |
|---|---|---|---|
| 0 | 140 ms | 0 pu | Held flat |
| 140 ms | 1.2 s | 0 → 0.8 pu | Ramps linearly |
| 1.2 s | 2.5 s | 0.8 pu | Held flat |
| 2.5 s | 3 min | 0.85 pu | Held flat |
| 3 min | plotted to 10 min | 0.9 pu | Held flat |
The clause this came from
Ceylon Electricity Board, Grid Connection Code, Grid Code - Revised September 2023 (PDF published July 2024, ceb.lk '1723552921Grid_Connection_Code_for_publishing_in_CEB_web.pdf'), section 3.17.3 'Fault Ride Through / Low Voltage Fault Ride Through (LVRT)', Figure 3.17-10 'Fault Ride Through requirement - Voltage duration curve' (p.32). The code defines a linear recovery ramp; the vertices are read from the clause and the chart draws the segment between them.
What is the frequency ride-through envelope for Sri Lanka (CEB)?
The plant must ride through between the upper and lower bands. The upper (over-frequency) band holds 53 Hz from t = 0 to 20 s; then 52 Hz from 20 s to 20 min; then 51.5 Hz from 20 min to 90 min; then 51 Hz from 90 min onward — the last band the envelope defines, with no stated end time. The lower (under-frequency) band holds 47 Hz from t = 0 to 60 s; then 47.5 Hz from 60 s to 90 min; then 49 Hz from 90 min onward — the last band the envelope defines, with no stated end time.
Every breakpoint is stated in the clause cited below.
Applies to Generators connecting to the CEB transmission grid
Upper limit
| From | To | Frequency | Between the points |
|---|---|---|---|
| 0 | 20 s | 53 Hz | Held flat |
| 20 s | 20 min | 52 Hz | Held flat |
| 20 min | 90 min | 51.5 Hz | Held flat |
| 90 min | no stated end | 51 Hz | Held flat |
Lower limit
| From | To | Frequency | Between the points |
|---|---|---|---|
| 0 | 60 s | 47 Hz | Held flat |
| 60 s | 90 min | 47.5 Hz | Held flat |
| 90 min | no stated end | 49 Hz | Held flat |
The clause this came from
CEB Grid Connection Code, Grid Code - Revised September 2023 (published July 2024), section 3.17.1.1 'Frequency ranges' I. Operating ranges (b), table on p.20.
Who does Sri Lanka (CEB) bind, and since when?
Generators connecting to the CEB transmission grid. No date of effect is published here — grid codes are reissued, so check the current issue before relying on it.
These figures are a reading aid, not legal advice. Grid codes are reissued: verify against the current edition before you design to them.
Digitised operating parameters beyond ride-through — droop, reactive capability, operating ranges — are published for 36 of the 66 codes in this atlas, not yet for Sri Lanka (CEB). That is a gap on this site, not a statement that Sri Lanka (CEB) sets none — the atlas hub marks the codes that carry them.
Curve data last checked against the code on — 66 standards, 130 envelopes, published by bess.engineer under CC BY 4.0.
Questions this page answers about Sri Lanka (CEB)
- Does Sri Lanka (CEB) require ride-through, or only that the plant does not trip?
- Ride-through. Every envelope on this page is a performance duty the plant must meet, not a protection-setting no-trip boundary — they are different obligations. That is what these curves are; they are not everything Sri Lanka (CEB) contains. The requirement sentence under each chart says which side of the curve is the compliant one.
- Are the numbers on this page taken from Sri Lanka (CEB) itself?
- Every breakpoint is read from the code, and where a point was taken off a published figure rather than stated in the clause, the section under that chart says so — on this page that includes an envelope that stops where its published chart stops. The clause each curve came from is quoted under it.
- Which events are charted for Sri Lanka (CEB)?
- Sri Lanka (CEB) is charted here with 2 envelopes — low-voltage ride-through, frequency ride-through (LVRT, FRT). No high-voltage envelope is charted here — check Sri Lanka (CEB) itself before concluding it sets none.
Ride-through, in context.
An envelope is a compliance boundary; understanding why it exists is a different question. The ride-through and grid-forming entries cover the engineering, and the Engineering Foundations course builds it from the physics up.
Elsewhere in Asia-Pacific: South Korea (KEPCO), India (CEA Connectivity Regs), Malaysia (Grid Code Additional Code 2025), New Zealand (EIPC cl 8.25A), New Zealand North Island (EIPC cl 8.19(1)), New Zealand North Island (EIPC cl 8.25A), and 9 more