Interface F Bushings & High Voltage Power Cable Connectors
Published 23 Apr 2025
Author | Rialdo Suwandi
Founder at Aldora Electric | Expert in Renewable Electrical Engineering & Cable Systems | Problem Solver | FIEAust CPEng NER
HV Bushings & Connectors
What Are Interface F Bushings?
How Do To Select the Right Cable Connector?
As medium voltage (MV) power systems grow in scale and capacity, manufacturers have introduced electrical equipment, such as transformers and switchgear, capable of handling up to 1250A at 52kV and 2500A at 36kV.
To ensure interoperability across manufacturers, these Interfaces are standardised under EN 50180 and EN 50181 as Interface F Bushings.
Furthermore, EN 50673 standardises 630A and 1250A bushings at 72.5kV.
What Are Interface F Bushings Used For?
Interface F bushings are typically used to connect gas-insulated switchgear (GIS) and transformers to cable circuits using separable connectors distributing electrical power at 11kV, 33kV and up to 66kV – manufactured by Nexans Euromold the connectors are suitable for cable termination of polymeric (XLPE EPR) insulated cables with copper wire or copper tape screen, wire armoured (SWA/AWA), wire braided or unarmoured cables into MV-HV Electrical Equipment with Interface F bushings.
Advantages of Electrical Equipment BushingsÂ
- Compact switchgear and transformer designs
- Interoperability across different manufacturers
Types of Interface F Bushings
As defined in EN 50180 and EN 50181:
F1 Bushings: Um ≤ 36 kV; Ir = 2500 A
F2 Bushings: Um ≤ 52 kV; Ir = 630 A
F3 Bushings: Um ≤ 52 kV; Ir = 1250 A
For 72.5kV high voltage power systems, EN 50673 defines the following:
F4 Bushings: Um = 72.5 kV; Ir = 630 A
F5 Bushings: Um = 72.5 kV; Ir = 1250 A
Note: F5 interfaces are commonly used in offshore wind applications but can adopted for large onshore installations as well.
Pictured | Nexans Q900AR-1Q900AR-2 Interface F Equipment Bushing 52kV MV HV
How to Select the Right High Voltage Separable Connector for Interface F Bushings
To ensure proper fit and reliable performance the following information must be established:
Interface type? e.g. F1
Maximum system voltage? e.g. Um = 36kV
Cable insulation type? e.g. XLPE
Conductor material and cross-section? e.g. copper, 800sqmm
Insulation over-diameter? e.g. 52.8mm
Number of circuits per phase? e.g. 2 circuits
Are surge arresters required? Confirm via an insulation coordination study
Interface F bushings enable safe, standardised, and high-capacity MV cable connections to GIS, and transformers, both for on-shore and off-shore applications.
Selecting the correct separable connector Interface F Connector —matched to interface type, voltage, current, cable type, and system design—ensures long-term reliability, safety, and maintainability.
Definitions of International Electrical Standards
EN 50180 | This European Standard is applicable to ceramic and resin insulated bushings having highest voltages above 1kV up to 52kV, rated currents from 250A up to 3150 A and frequencies from 15 Hz up to 60 Hz for insulating liquid filled transformers. This European Standard establishes essential dimensions, to ensure interchangeability of bushings and to ensure adequate mounting and interchangeability of mating plug-in separable connectors of equivalent ratings.
EN 50181 | This European Standard is applicable to insulated bushings for maximum voltages above 1kV up to 52kV, rated currents from 250A up to 2 500A and frequencies from 15 Hz up to 60 Hz for equipment other than liquid filled transformers. This European Standard establishes essential dimensions, to ensure adequate mounting and interchangeability of mating plug-in separable connectors of equivalent ratings.
EN 50673 | Extend the scope of the EN50180-1/2/3 and EN50181 for plug-in type bushings up to 72.5 kV
Thorne & Derrick distribute the most extensive range of MV HV Medium & High Voltage Cable Joints, Terminations & Connectors from manufacturers including 3M, Prysmian, Nexans Euromold, Elastimold, Pfisterer CONNEX & SEANEX and Shrink Polymer Systems.
