[AU] Dynamic Cable Ratings Webinar

​Join us for a 1-hour technical webinar on dynamic (cyclic) cable ratings: how to calculate the real current-carrying capacity of buried cables under a repeating daily load profile, and how much capacity a steady-state calculation leaves on the table. This free session is for power and cable engineers sizing circuits with variable, peaky duty, from solar and wind collector cables to HV transmission and submarine export cables.

​A steady-state rating assumes the cable carries its worst-case current continuously. Almost no real circuit does. In the worked example, five buried 240 mm² aluminium solar feeders rated 255–285 A by IEC 60287 settle at around 47–52 °C under their actual midday-peaking duty, roughly 40 K below the 90 °C XLPE limit. That margin is usable capacity, and this webinar shows how to quantify it.

​Run the calculation properly, and the same five feeders support a cyclic rating 38% above the continuous rating, a peak of 353 A instead of 255 A, lifting daily throughput from 3.34 to 4.96 MWh per feeder. Across the installation that is 8.1 MWh more every day, equivalent to more than two additional feeders, with no change to the cable, the duct or the trench.

​Getting there depends on two things that are routinely missed: running the model long enough for temperatures to settle, and knowing the soil's heat capacity, not just its resistivity. We will show why a single 24-hour calculation returns an unsafe answer, and why these feeders needed 23 to 38 days of simulated time before the daily peak stopped moving.

​The method is voltage-independent: the example is an LV/MV PV collector, but it applies equally to HV transmission and submarine export cables. Results are computed with the multi-step transient method in ELEK Cable HV™, built on the CIGRE Electra No. 87 thermal-network approach and extended by ELEK beyond the limits of IEC 60853, and validated both against IEC 60287 at steady state and against CIGRE WG B1.67 finite-element transient calculations.

​What You'll Learn

​➤ Why Steady-State Ratings Leave Capacity Unused

​How IEC 60287's 100%-load-factor assumption is built into every conventional rating, why the resulting margin is recoverable capacity rather than a safety factor, and where the published gains sit, EWEA reports up to 15% more transmissible power for deeply buried cable and up to 50% conductor cross-section reduction at landfalls.

​➤ Thermal Inertia and Why Burial Depth Changes the Timescale

​Conductors respond in hours, soil in months to years. Settling time grows roughly with the square of depth, from months at 1 m to about 15 years at 10 m, which is why at HDD and landfall depths, a cable never reaches steady state within its service life.

​➤ The Soil Property Missing From Your Data Request

​Volumetric heat capacity controls how long a circuit takes to settle (tripling it from 1 to 3 MJ/(K·m³) triples settling time from 114 to 336 days) while leaving the final temperature unchanged. Thermal resistivity changes both. Steady-state data requests routinely ask for one and not the other.

​➤ Starting Conditions and Why One Day Is Not Enough

​Compare a preloaded start at the 90 °C limit against a cold no-load start. Day one peaks at just 38 °C against a settled 47 °C, a 9 K under-read, and the two start bracketing the true answer from above and below. Learn the convergence test that tells you when it is safe to stop.

​➤ Calculating the Cyclic Rating, A Worked Five-Feeder Example

​Five buried solar collector circuits of 240 mm² aluminium XLPE in trefoil ducts, running side by side with mutual heating between them. We scale the real load profile until the hottest circuit reaches 90 °C, and read the cyclic rating from the settled cycle, showing why the same scaling, judged on a single day, would return a dangerously optimistic result.

​➤ Beyond IEC 60853: Rating From Real Load History

​IEC 60853 and Neher–McGrath handle one repeating 24-hour cycle or a single step. Real duty is not that. See what becomes possible when the transient model accepts arbitrary multi-step patterns, non-repeating and seasonal sequences, years of measured generation data, and transient mutual heating across a group of circuits.

​➤ How to Validate a Transient Rating Tool

​Two independent checks any tool should pass, and how to run them: hold each circuit at its IEC 60287 rated current, and the settled temperature must land on the limit (89.66 °C against 90 °C here, after a year of simulated time), and the transient response must match a finite-element solution.

​Why You Should Attend

​Conservative continuous sizing is expensive for circuits that rarely run at their peak, and for solar farms, wind arrays, and export cables, that is, most of them. This session gives engineers a defensible method for claiming cyclic capacity, the input data to insist on before they do, and the validation checks to prove the answer. It is most valuable to anyone specifying new collector or export circuits, or assessing whether an existing variable-load circuit genuinely needs upsizing.

​Event Details

​- Duration: 1 hour

​- Presenters: Jayson Patrick (Technical Director) and Dr Omair Khan (Senior Technical Researcher)

​- Delivered live twice for Australia (2:30 pm GMT+10) and Europe (2:30 pm GMT+0)

​- Includes live Q&A and certificate of attendance

​TERMS AND CONDITIONS

​- Attendees who complete the survey form will receive their certificate within 2–3 business days.

​- Survey forms expire within 48 hours after the webinar.

​- Paid ticket holders who do not complete the survey will still receive the slides and recorded videos.

​- Paid ticket holders will receive materials within 5–6 business days after the webinar.