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HV substations and the transmission grid: what changes above 50 kV

Above 50 kV it is no longer an equipment purchase: it is a project. Interlocutor, framework, tests, exceptional transport, and why range lead times do not apply there.

MV, HV: where the boundary runs

In France, HTA (MV) runs up to 50 kV and HTB (HV) beyond. That boundary is not just numbers: it changes the interlocutor, the framework, the equipment and the schedule. At MV, your counterpart is the distributor (Enedis or a local company) and the framework is NF C 13-100. At HV you enter transmission territory: RTE operates the network, and the installation falls under a different regime. Applicable thresholds and regimes follow the texts in force, validated with your design office and the operator concerned.

Why an HV project is not a "big MV"

The power transformer changes nature: engineered from your single-line diagram, it has nothing left of a range product. The bushings become critical, long-lead components. The tests go beyond routine: type tests, dielectric tests, often a FAT with witnesses. Transport becomes exceptional, convoy, route, permits, sometimes dedicated civil works for access. And the HV switchgear, protections and control systems form a whole of their own. In other words: no longer an equipment purchase, a project.

The typical run

Studies and sizing: single-line diagram, protection plan, civil works. Everything is decided here; the schedule is built here too. Manufacturing and tests: the power transformer is built to order, then tested at the factory; the test programme is fixed at quotation. Transport and commissioning: exceptional convoy, erection, site tests, then energisation with the network operator. Each stage carries its own planning, established from your specification.

Why our range lead times do not apply in HV. The 15–18 week delivered schedule covers the standard distribution ranges. An HV project is engineered end to end: we prefer to say so at quotation stage rather than have you discover it mid-route. Give us the target date; we build the plan backwards from it.

What we bring on an HV project

The same model as in distribution, applied to a heavier object: we define the specification with you, production goes to partner factories qualified for the target rating, we are present on the production side (audits, follow-up, hold points, FAT), and we carry the manufacturer's obligations on the European market, technical file, declaration of conformity, documentation. One interlocutor, from study to energisation.

What to send us

The single-line diagram, the target power and voltages, the neutral regime, the protection plan if it exists, the site constraints (access for an exceptional convoy, footprint, civil works), and the desired commissioning date. With those elements we come back with a schedule and a price, not a token range.

General overview of the French HV logic; regimes, procedures and requirements follow the texts in force and the operator, confirmed on your file.

Frequently asked

Where is the boundary between MV and HV in France?

Conventionally 50 kV: below, HTA (distribution); above, HTB (transmission). Crossing that line changes the operator (Enedis to RTE), the framework and the nature of the project. Applicable thresholds and regimes follow the texts in force.

Do your range lead times apply to HV projects?

No. A power transformer is engineered to order from your single-line diagram, with its own test programme and exceptional transport: the schedule is built with your specification, and we prefer to say so at quotation rather than discover it mid-route.

Who is the interlocutor for an HV connection?

The transmission system operator, RTE in France, under its own regime. Your design office frames the connection; we align the equipment, tests and documentation on that file.

What should I send you for an HV project?

The single-line diagram, the target power and voltages, the neutral regime, the protection plan if it exists, the site constraints (convoy access, footprint, civil works) and the target commissioning date. With that we return a schedule and a price, not a token range.

Go further

Engineered to spec

An HV project? Send the single-line diagram.

Describe the project →