prEN 50708-3-301:2026

Oil-immersed cable connection assemblies for transformers and reactors having highest voltage for equipment Um from 72,5 kV to 550 kV - Part 1: Fluid-filled cable terminations prEN 50708-3-301:2026

Scope

This document covers the oil-immersed single-phase connection assemblies of cables for transformers and reactors designed in accordance with the EN 60076 series.
NOTE The term “transformer” is used as common definition for power transformer and reactor.
If no separate cable connection box is used and cable terminations are directly installed into the transformer tank the requirements of this standard are followed.
The purpose of EN 50708 3 301 is to establish for the cable connection assemblies:
• electrical and mechanical requirements including interchangeability;
• limits of supply;
• tests to be carried out.
It complements and amends, if necessary, the relevant standards and applies to dry-type cable terminations for power cables with extruded insulation which can be used with similar interfaces for the cable entrance in switchgear applications according to EN IEC 62271 209.
This document applies to liquid-filled cable connection boxes of transformers with highest voltage for equipment from Um = 72,5 kV to 550 kV, including the conductor current terminal with removable link between the transformer and the dry-type cable termination.
Annex A is applicable to liquid-filled cable terminations.