Cables for Power Transmission and Distribution
Power cable selection starts with voltage class, because it determines the insulation system rather than just its thickness. Low voltage cable can be insulated with PVC or XLPE; medium voltage cable needs extruded semiconductive screens on both sides of the insulation, and those screens are what control the electric field and prevent partial discharge.
The second decision is installation method. Direct burial, duct, tray and aerial each impose different mechanical and moisture requirements, and armouring is usually driven by that rather than by electrical load. Getting these two decisions right is most of the specification.
What decides the cable in this application
Four factors do most of the work. Getting these right narrows the choice to a small number of constructions, and each one appears in the specification table of the cable type you select.
Voltage class determines the insulation system
Medium voltage cable needs semiconductive conductor and insulation screens, triple-extruded to eliminate voids. Without them, partial discharge starts at voids and erodes the insulation from the inside.
Partial discharge is the decisive factory test
A voltage withstand test can pass a cable that has voids. Partial discharge measurement detects them, which is why it is the definitive check on medium voltage insulation integrity.
Installation method drives mechanical protection
Direct burial, duct and aerial installations each require different mechanical protection. Steel wire or tape armouring is normally selected for the installation conditions rather than for the electrical rating.
Conductor class affects route and termination
Stranded and flexible conductor classes bend differently and terminate differently. The class has to suit the route through the installation as well as the current.
Cable types for power transmission
12 constructions from the catalogue that suit this duty. Each links to its own page with the full specification table.
What we need to quote accurately
Send these six items and we can confirm a construction and price without a follow-up round. Both the contact page and every product page carry a form that accepts them, and you can attach a drawing or specification sheet directly.
- 1 Voltage class 0.6/1 kV, 3.6/6 kV, 6/10 kV, 8.7/15 kV and above
- 2 Conductor size and core count Cross-section per phase, plus neutral and earth
- 3 Insulation type PVC for lower ratings, XLPE where thermal and dielectric performance is needed
- 4 Installation method Direct burial, duct, cable tray, aerial, or indoors
- 5 Armouring and sheath Whether mechanical protection is required, and the environment
- 6 Route conditions Bend radii available, pulling tensions, terminations and joints
Frequently asked questions
When does a cable need XLPE rather than PVC insulation?
Where the operating temperature or the dielectric requirement exceeds what PVC handles well, or where the cable runs a reeling or flexing duty alongside power transmission. XLPE tolerates higher conductor temperature and has lower dielectric loss.
Why do medium voltage cables need semiconductive screens?
Air voids at the conductor and insulation surfaces are where partial discharge begins and erodes the insulation. Triple-extruding the conductor screen, insulation and insulation screen in one continuous process removes those voids at the source.
When is steel wire armouring required?
Normally where the installation imposes mechanical load — direct burial, routes with crush risk, or vertical runs where the cable supports its own weight. The armour is selected for the installation conditions, not for the electrical rating.
How is partial discharge verified?
By measuring the discharge magnitude at a defined test voltage, with the acceptance level stated in picocoulombs. It is the definitive factory check on medium voltage insulation, because it detects defects that a simple voltage withstand test would pass.
Other applications
Need the cable confirmed against your machine?
Send the duty, the environment and the electrical data. Our engineering team will confirm the construction, the standards it meets, and the price — including custom builds where a catalogue type does not fit.