Jointers Tools | 66kV Cable Preparation Tools | Some Recommendations
Published 09 Nov 2018
uploaded by Chris Dodds- Thorne & Derrick Sales & Marketing Manager
66kV XLPE Cables
Jointer Training & Tools
Thorne & Derrick are Specialist Stockists & Distributors of cable joints and terminations for 66kV power cables – this includes the provision of 66kV Jointer Training using Nexans Power Accessories UK facility. To support the installation of 66kV joints, terminations and connectors we stock and distribute a full range of Jointers Tools to enable the preparation of all critical stages of the cable stripping process – this includes removal of cable sheath, insulation XLPE, lead sheath and bonded semicon screens.
Manufacturers of cable preparation tools provide competing options in the design, functionality and application of their cable tools – it is usually a mixture of cable jointers personal preference and client approval which informs the tool selection process, nevertheless the following information provides guidance and some recommendations for tools to use when stripping 66kV cables.
Can I Use Standard 33kV Tool Sets To Prepare 66kV Cables?
Although 66kV is classed as high voltage, due to the construction diameters of 66kV cables often 33kV medium voltage cable preparation tools can be used – for the Nexans Jointers Training Courses the standard MV cable tools are compatible with the training cable up to 300sqmm at 66kV.
However, for future 66kV projects it would be necessary for the jointer to upgrade their tool set to enable the preparation of larger diameter cables above 300sqmm conductors.
Naturally, when using medium voltage category tooling there will be a requirement for the cable jointer to undertake additional glassing of the XLPE insulation to achieve the required chamfer prior to installing the MV HV joint, termination or connector.
Cable Sheath & Lead Sheath Removal
Typically, Alroc cable sheath stripping pliers, PG types, would be used for removal of the outer cable sheath/jacket depending on the outside diameter of the cables to be jointed and terminated – these tools effectively strip the PE (polyethylene) sheath from medium/high voltage power cables. The lead sheath (Pb) is generally removed using jointers knives – the lead sheath should be carefully scored and then peeled from the cable.
Cable Insulation & Bonded Screen Removal
Note for larger diameter 66kV power cables, 300sqmm+, the standard 33kV cable preparation tools will be unsuitable – for removal of XLPE insulation with bonded screens we would recommend Alroc CAMF4/40-90 tool.
The 66kV Training Course utilises single core 300sqmm cables with a 48.1mm diameter over the bonded semicon screen – depending of jointers preference any semicon shaving tool from reputable manufacturers including Alroc, Ripley or Boddingtons could be used.
Similarly, any XLPE cable insulation removal tool suitable for 46.1mm primary insulation diameter cable could be used.
The preferred bonded screen stripping tool is used to leave various lengths of black insulation screen from the outer sheath cut and the measurement varies depending on the type of joint, termination or connector.
Chamfer & Polish
For the chamfer we would recommend the Alroc GRI tool along with conventional glass to achieve a smooth finish to the XLPE insulation – the cable insulation would then be polished using aluminium oxide abrasive strips, usually 180/240 grit and 400 grit.
The XLPE insulation must be polished smooth with an appropriate aluminium oxide grit paper until the XLPE surface is smooth and wrinkle-free. To finish this process, reverse the paper and “buff-up” with the smooth side.
Typically 66kV Cable Specification
➡ The following cable specification is based on 66kV XLPE Insulated Lead Sheath Single Core 300sqmm cable to IEC 60840:
|Single Core Cable with Copper Round Compacted Conductor, XLPE Insulated, Lead Sheath, Polyethylene Oversheath|
|66kV Cable Code||714242019533**|
|Standard Specification||IEC 60840 Generally according to NPS/002/022|
|Type of Cable||XLPE/PB/MDPE|
|Rated Voltage Uo/U (Umax)||38/66 (72.5kV)|
|Number of Cores x Nominal Cross-section||1 x 300sqmm|
|Approximate Cable Overall Diameter||59mm|
|Approximate Cable Overall Weight||8.4kg/m|
|Nominal Drum Length (Tolerance)||500m (-0%, +0%)|
Cable oversheath marking by embossing in two lines as follows:
- CABLEL 0317 2016 09* ELECTRIC CABLE 66000 VOLTS IEC 60840 1×300 CU ‘ref number’**
*Year and month of manufacture
** Insulation Core Lot number (8 digits by embossing and 2 last digits by indenting)
- By ink – meter marking at on metre intervals
66kV Cable Structure
Cable Manufacturer Hellenic Cables S.A.
Annealed bare copper round strand compacted class 2 BS EN / IEC 60228 of nominal cross-section equal to 300sqmm longitudinally waterblocked by waterblocking yarns and/or waterblocking tapes and/or waterblocking powder between conductor inner strands (approx diameter over 20.4mm)
- Semiconductive tape applied helically with overlap
- Conductor non-metallic extruded screen:
Extruded semiconducting compound of 1.0mm nominal thickness (0.60mm minimum at any point thickness)
XLPE super-clean according to IEC 60840 of 12.0mm nominal thickness (minimum average thickness of 11.0mm, minimum at point thickness 10.80mm – approx diameter over insulation 46.1mm)
- Core non-metallic extruded screen:
Extruded semiconducting compound bonded to insulation of 1.0mm nominal thickness (0.60mm at any point of thickness)
- Semiconductive waterblocking tape applied helically with overlap
- Metallic sheath:
Lead alloy type PK021S or other suitable alloy type according to EN 50307 of 2.0mm nominal thickness
- Cable sheath
MDPE type ST& according to IEC 60840 of 2.7mm nominal thickness.
Sheath colour: Black
- Extruded semiconducting compound serving as electrode for the DC voltage test of the oversheath