Triplex Cleats – Selection Guide for Cleating 11kV BS7870 Part 4.10 Cables

Published 25 Jul 2018

  • uploaded by Chis Dodds – Thorne & Derrick Sales & Marketing Manager

The following post is provided to enable the selection of cable cleats to suit a standard UK DNO utility cable for medium/high voltage power systems – this type of MV HV cable commonly referred to as “Triplex” cable has increasingly replaced conventional BS6622 11kV 3 core XLPE insulated cable.

Triplex cable consists of 3 x single cores in a “twisted” spiral formation – this non linear cable orientation must be recreated into a circular formation using Triplex cable surrounds.

It is essential to effectively cable cleat Triplex cables to containment to ensure safe and reliable cable restraint in the event of a short-circuit situation – to simplify the cable cleat selection process it is a basic requirement to consider the calculated short-circuit fault current rating, installation environment and overall outside diameter of the 3 x single core cables when combined in Triplex formation.

The short circuit calculation would normally be the responsibility of the Electrical Design Engineer and can be calculated using a formula as recommended by IEC61914 the international standard  which specifies requirements and tests for cable cleats and intermediate restraints used for securing cable in electrical installations.

Cable Cleats

Triplex Cables 11kV BS7870 4.10

Specification: 11kV Triplex, Solid Aluminium Conductor, Triplex Extruded Conductor Screen, XLPE Insulation, Fully Bonded Semi-con Screen, Copper Wire Screen, Longitudinal Water Blocking Tape, MDPE Cable Sheath, 6350/11000V to BS7870 Part 4. Sheath colour: Red.

Based on the following 11kV Triplex specification we can recommend and supply 3 types of cable cleat

  1. Ellis Patents 2F Cable Cleat (Plastic)
  2. Ellis Patents Vulcan+ Cable Cleat (Stainless Steel)
  3. Ellis Patents Emperor Cable Cleat (Stainless Steel)
Voltage  Conductor Type Conductor Sqmm Nominal Conductor Diameter Dia Over Insulation mm Dia Over Semi-con Screen Dia Over Cable Sheath Diameter In Triplex Formation Triplex Liner 2F Cleat Vulcan Cleat Emperor Cleat
11kV Solid Aluminium 95sqmm 10.65mm 18.95mm 23.03mm 27.17mm 58.24mm SFT26 2F+10 VRT+04 ES58-66
11kV Solid Aluminium 185sqmm 14.9mm 23.25mm 27.33mm 31.67mm 68.24mm SFT31 2F+1200 VRT+06 ES65-73
11kV Solid Aluminium 300sqmm 19.0mm 27.3mm 31.38mm 36.12mm 77.83mm SFT36 2F+1201 VRT+07 ES73-85

 

♦ Important: Manufacturers cable dimensional data and tolerances can vary by significant % factors hence critical measurements can be inconsistent – always provide manufacturers cable specification complete with construction information to ensure supply of correct cable cleats. Above is provided for guideline purposes only – check with Thorne & Derrick.

Based on the above cable dimensions we can supply the range of cable cleats listed below.

Triplex Liner & Cable Surrounds

Ellis Patents Triplex cable surrounds are manufactured from LSF Zero Halogen Polymeric material and used within single cable cleats to secure triplex cables – the cable liner surrounds have a maximum short circuit test level of 76kA when used with Ellis Patents 2F cable clamps and 600mm cleat spacings.

Triplex Cleats

Triplex Cleats

The following table provides an overview of the Ellis Patents range of Triplex cable cleats depending on levels of short circuit fault protection required by the clamps.

 

More Cable Cleats Reading

Cable Cleats

Ellis Patents Cable Cleats

Further Reading