Copper Cable Lugs For Special Applications
Published 03 Sep 2018
uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
Thorne & Derrick International, based in the UK, are leading suppliers of cable crimp lugs and associated crimping tools for Low, Medium & High Voltage Cables and Power Systems – this series of articles by Klauke discusses the theory and practise of installing compression type cable lugs and connectors.
Klauke cable lugs and crimping tools are used by Jointers, Linesmen, Panel Builders and Electrical Engineers to install underground cables and overhead line conductors on power, transmission and distribution networks including LV MV & HV systems, 11kV-33kV.
In this Article we cover the following:
- Crimping cables according to Class 5 & Class 6 DIN 57295 using Klauke “F” cable lugs
- Tube diameter is matched to the conductor size to guarantee a professional cable crimp
- Cable lugs for switch cabinets with special narrow palm cable lugs
- Crimping copper cables and conductors using stainless steel and nickel cable lugs
A well known problem for every electrician or cable jointer is trying to insert a stranded or fine stranded conductor into the cable lug or cable splice and some wires cannot be inserted. To avoid this problem renowned manufacturers offer specialist application connectors and cable lugs for the jointing and termination of LV MV HV cables.
Cable Lugs, Strandings & Conductors
With these specialist application cable lugs all types of cables can be used – the design and construction of the cable lug to be selected is determined by the cable stranding and conductor type. The cable conductor characteristics of cable types are as classified in the DIN Standard 57295.
Class 1 is a solid/round conductor providing both the smallest diameter and largest cross-sectional area (CSA in sqmm) – this is the simplest conductor but mechanically weak with solid conductors prone to breakage after several bending cycles. The cable conductors are categorised into Classes based on the total number of strands per conductor – the higher the Class, the more strands in the conductor:
- Class 1 Round single / solid conductors
- Class 2 Round multi-stranded conductors – typically 7 or 19 strands
- Class 5 Fine stranded conductors (Multi-stranded general flexible use)
- Class 6 Fine stranded conductors (Extra multi-stranded dynamic use)
DIN 57295: DIN VDE 0295:1980-09; VDE 0295:1980-09
Conductors of Cables & Flexible Cords For Power Installation (VDE Specification)
Cable Lugs For Fine & Very Fine Stranded Conductors
The above mentioned problem of spliced cables per Class 5 and Class 6 according to DIN 57295 is being avoided when using Klauke “F” type series cable lugs. These lugs are designed for processing larger cross section conductors in voltage applications up to the short circuit tested rating of the cable lug.
Compared with standard tubular cable lugs the “F type” lugs have a larger tube diameter – the cable lugs have a flared entry which eases cable location into the barrel of the lug.
The advantages are obvious – “F type” cable lugs ensure an easy and safe insertion of the conductor, the unravelling of the cable strands is avoided and the complete conductor fits into the cable lug prior to compression using appropriate crimping tools and die sets.
This is also a safety-related issue – a reduction of the cross section area of the cable conductor caused by not inserting all the strands is being avoided and the complete cross section of the cable is maintained. Markings on the F-type cable lug barrel provide information of the product, e.g. manufacturer, dimension and design.
Marking “KL 12 150 F” indicates:
- KL: Manufacturer Klauke
- 12: Metric bolt size for connecting bolt: size M12
- 150: Cross section of conductor in sqmm
- F: Tubular cable lug design and construction
For professional crimping of F-type cable lugs the indent or quad point crimping method is recommended with the appropriate crimping tools and the correct indent profile.
To avoid over or under compression the correct tooling is a pre-requisite. An incorrect crimping connection can result in increased joint resistance leading to an increase in temperatures and in the worst case in fire.
Klauke recommends use of their own crimping tools to achieve and guarantee professional crimps according to VDE standards. In addition to “F-type” cable lugs some manufacturers offer appropriate butt-connectors for splicing, extension and repair of cable conductors.
They also feature a flared entry and larger tube dimensions. A central restriction insures uniform insertion of the cable ends, and insure the crimping recommendations for F-type lugs are adhered to.
“F-type” cable lugs and butt connectors conform to the normative requirements of the EN 13600 standard and are manufactured from electrolytic copper for excellent conductivity.
For corrosion protection the cable lugs are available tin plated from cross sections ranging between 10sqmm up to 300sqmm. In addition to the normal design “F-type” cable lugs are also available as 45° resp. 90° angled versions as well as inspection holes to check whether the conductor is fully inserted prior to crimping-up the lug using the cable tool.
As with all other connections these products are subject to test standard IEC 1238 Part 1, which guarantees a safe electrical and mechanical connection has been achieved. Cable lugs manufactured by Klauke are subject to a special annealing process to help relieve material stresses and hardness.
This reduces the chance of material fracture and is an additional safety feature. The quality of cable lugs can often be recognised by visual characteristics. A burr free lug, a flat palm and a cleanly machined end are indicative of a high quality product.
Note: IEC 61238-1:1993 Is Now Withdrawn. Compression & Mechanical Connectors For Power Cables With Ccpper Or Aluminium Conductors – Part 1. Contact T&D.
Cable Lugs For Solid Conductors
For processing and crimping solid conductors (Class 1 DIN VDE 57295) the use of tubular cable lugs “E” type is recommended which are also manufactured from electrolytic tin plated copper. Their tube diameter is matched to the conductor size to guarantee a professional cable crimp.
Application is in all areas where solid conductors are being mostly used, e.g. manufacture of switchgear, transformers and engines.
A hexagonal indent crimping is being recommended – again it has to be observed that both cable lugs and crimping tools come from the same manufacturer.
Cable lugs for solid conductors can be recognized by their smaller tube diameter and the marking “E”. For example: KL 10 50 E.
Cross sections usually range from 6sqmm up to 50sqmm. The range is being completed by butt-, T- and cross connectors having the appropriate internal tube diameters.
Cable Lugs For Switch Cabinets
In many cases working area in switch cabinets is very tight and connecting conductors to high-power switchgears can be a problem In case of larger cross sections standard cable lugs do not fit into the compact connecting terminal.
For such applications many manufacturers have designed special narrow palm cable lugs (Klauke SG cable lugs) which fit comfortably.
The narrow palm lug is also thicker than standard cable lugs ensuring the same amount of electrolytic copper has been used.
Despite a narrower palm no performance is lost. Thus these cable lugs therefore comply with a professional connection for stranded conductors according to DIN- VDE Class 2 as typically used in switch cabinets.
A hexagonal or indent crimp is recommended – conductor cross sections range from 35sqmm up to 300sqmm. The hole dimensions comply with industry sizes of connecting terminals, e.g. 6, 8, 10, 12 and 16mm.
Versions with inspection holes are also available – it is dangerous and incorrect to file the palm of a normal cable lug to the size of the connecting terminal. Such manipulation can result in increased temperatures and fire in the worst case.
Stainless steel cable lugs
for aggressive environments
Especially for adverse environments and for crimping copper conductors stainless steel and nickel tubular cable lugs have been designed. Stainless steel cable lugs are particularly acid and corrosion resistant and are typically used in chemical industries in areas exposed to sea water i.e. the earthing of masts on sailing yachts.
An additional benefit of these cable lugs is the temperature resistance. Consequently these lugs can be used in ambient temperatures up to 400°C.
At higher temperatures of up to 650°C – common in the construction of furnaces – nickel cable lugs represent the best solution. Both stainless steel and nickel cable lugs can be used for all common cable types.
Cross section ranges from 0.5sqmm up to 95sqmm. Generally an indent crimp is recommended. The same applies for stainless steel and nickel butt connectors with barrier.
Review other Blogs in this series of articles about Cable Lugs, Crimping Cables & Tools:
LV MV HV Cable Accessories & Substation Electrical Equipment
Thorne & Derrick are Specialist Distributors of leading manufacturers of Cable Accessories, Jointing & Installation Equipment.
LV MV HV cable accessories used to joint, terminate, connect, cleat and gland power cables to air and gas insulated substations, transformers, switchgear and overhead line networks.
Hover over our Interactive Electricity Grid to learn more about our product ranges.
LV 600/1000V ◊ MV 11kV 33kV ◊ HV 66kV 132kV
Substation & Overhead Line Electrical Safety Equipment
Manufactured by CATU Electrical to enable the safe construction, maintenance and repair of underground cables and overhead lines network up to EHV (400kV).
T&D - CABLES ♦ JOINTS ♦ TERMINATIONS ♦ CONNECTORS ♦ GLANDS ♦ CLEATS ♦ CRIMPS & LUGS ♦ DUCT ♦ SEALS ♦ ARC FLASH PPE EARTHING ♦ FEEDER PILLARS ♦ JOINTERS TOOLS ♦ CABLE CUTTING & CRIMPING TOOLS ♦ COLD SHRINK ♦ HEAT SHRINK ♦ FUSES
- Klauke – Cable Lug & Connectors – Tools Crimping Cutting Section 1 Size: 11.50 MB
- Klauke – Cable Lug & Connectors – Tools Crimping Cutting Section 2 Size: 7.91 MB