In our last blog post, we looked at the requirements of the BS7609 code of practice which covers the installation and inspection of uninsulated compression connectors for power cables with aluminium or copper conductors.

However, there is more to simply following these engineering guidelines to achieve the ‘perfect crimp’.

There is more to crimping a cable than simply affixing a lug to the conductor. The BS7609 standard highlights the code of practice for installation and inspection of uninsulated compression and mechanical connectors for power cables with copper or aluminium conductors.

Conductor Type

Although a lot of focus is given to the crimp lug, die sets, tooling and crimp operation, thought should also be given to the cable and conductor. Even if the best quality electrical lugs and crimping procedures are used, the termination can still fail due to the conductor. Make sure the conductor used is both third-party approved and appropriately marked.

ETS support the work of the Approved Cables Initiative (ACI) Code of Practice in fighting the use of faulty, counterfeit and non-approved cables.

Cable Lug Current Carrying Capacity

The lug should have equal or greater current carrying capacity to that of the conductor. Using lug that have been manufactured with high purity, electrolytic copper allows the maximum level of conductivity with minimal resistance.

Lug manufactured from thin wall copper tube have the potential to cause elevated temperatures when used on conductors carrying high current levels.

Crimp Tooling

Care should be taken to ensure crimp tooling is kept in good working order. The crimp tool should regularly calibrated and serviced when required. All tooling and equipment should be checked for damage or wear before use. To help prevent damage to die sets and tools, they should be stored in the recommended way. E.g. Protective storage case.

Our maintenance guidelines to keep your hydraulic crimping tool in good condition highlight how to keep your tool in top condition and maximise it’s working life.

Die Selection and Number of Compressions

We supply full die set selection charts with all our standard, Cembre and Prysmian lugs. Referring to these guides allows you to match the correct tool, die set and lug, providing the best combination to achieve the best possible compression.

Always follow manufacturers guidelines concerning number of compressions per lug and in which sequence, to assure the performance of the termination after crimping and avoid distorting the lug.

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There is more to crimping a cable than simply affixing a lug to the conductor. The BS7609 standard highlights the code of practice for installation and inspection of uninsulated compression and mechanical connectors for power cables with copper or aluminium conductors.

The purpose of this code of practice is to give guidance to manufacturers and electrical contractors who use compression connectors and terminals to enable cables to be terminated in a safe, consistent and efficient manner following good engineering practices.

The following steps provide simple instructions on how to crimp a cable lug to BS7609.

How To Preform The Perfect Crimp?

1. Choose a supplier that provides crimp tooling, die sets and cable lugs which are compatiable and designed to work together to give the optimum crimping performance.

2. Each lug/terminal should have a reference clearly marked on the palm or barrel which enables the user to easily verify that it is the correct size and type for the conductor it is due to be used on.The crimp lug should also feature the manufacturers name or logo to enable the use of the correct tooling and die set, which can be selected from their published die set selector charts.

3. Prepare the aluminium or copper conductor for crimping by stripping back the insulation to a length equal to that of the lug barrel. This ensures that no insulation can be trapped in the barrel of the lug when assembled.

4. Insert the conductor into the terminal barrel. If applicable, use the inspection hole to check the conductor is fully inserted.

5. Perform the crimp paying careful attention to the positioning of the die on the barrel and, if multiple compression actions are required, in which sequence they should be performed.If using a hydraulic crimping tool, making sure the correct tool is used with a compatible die set is vital. Care should also be taken to keep the tool well maintained, working properly and has an up to date calibration certificate. More information can be found in our hydraulic tool maintenance guide.

6. Once the crimp(s) have been performed, check the completed termination for:

a) No insulation is trapped in the barrel

b) Check the inspection hole to confirm the conductor has been fully inserted

c) Over-crimping – make sure the barrel is not over crimped causing excessive stress on the conductor and flash or burrs on the lug

d) Under crimping – No air voids should be found between the strands of the conductor. They should be tightly compacted to ensure maximum performance

Over Crimped and Under Crimped Lugs

The below image shows an under crimped lug (left) and an over crimped lug (right). Both these incorrectly crimped terminals can cause overheating and ultimately lead to termination failure or fire. The over crimped lug is easily identifiable by the ‘ears’ or ‘wings’ of created on the barrel of the terminal. The under crimped lug is identifiable by inspection of the lug and conductors.

For more information on our range of hydraulic and battery powered crimping tools, please contact our Tooling Department.

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When specifying products for use within harsh environments, choosing the correct materials is vital. For example, in offshore oil and gas installations, equipment experiences exposure to high levels of seawater and salt-spray, which are highly corrosive due to the dissolved chlorides within. Offshore installations are not the only projects that experience harsh, corrosive environments, other corrosives that affect a wide range of industries include: chlorine, ammonia and hydrochloric acid.

In May we reviewed the effects of galvanic-corrosion between two dissimilar metals, in that example we explored the use of stainless steel cleats with galvanised steel support structures. Corrosion can take many different forms and choosing the correct materials and finishes is key to minimising its effects. We have outlined common corrosion control methods, explaining how and where they should be implemented.

Choosing materials based on their galvanic characteristics

Different metals have different electrode potentials, therefore when two different metals are electrically connected in the presence of an electrolyte, such as seawater, the more active metal will become anodic leading to loss of electrons and increasing oxidisation in a process known as galvanic-corrosion.

Metals and alloys are ranked in order of noble to active, in what is called the galvanic series. A more noble metal, such as stainless steel, will have much better corrosion-resistance than a more active metal such as cast iron.

Galvanic Series of Metals

Galvanic corrosion can be controlled and minimized by selecting metals in similar positions within the galvanic series. A more active metal can also be used as a sacrificial anode, attracting corrosion in order to protect the more noble metal from corrosive attack. Alternatively, depending on the installation, a cleat separation washer can be installed between the dissimilar metals increasing the distance between each metal and removing the electrical and physical contact points, critical to causing corrosion.

Passivation

During manufacturing, certain metals form a layer of metal oxide on the surface in a process known as passivation. Although the process occurs naturally, it can be enhanced through chemical passivation treatments and anodising. The layer protects against corrosion as it is tightly bound to the surface, preventing further penetration of oxygen and corrosive molecules.

The most common examples include aluminium and stainless steel. Usually, if these metals are damaged the layer reforms quickly, however this process is not without its faults. Pitting corrosion can occur in aluminium when chloride ions interfere with the reforming process and high chromium carbides can affect welded stainless steel.

If the products are properly selected for the intended application, passivated metals can provide high levels of corrosion-resistance. This is why stainless steel cleats are the preferred product within offshore installations.

Protective Finishes and Coatings

Various protective coatings can be applied to metals to help shield metallic surfaces from the surrounding environment, including epoxy power coating, oven-baked enamel, hot-dipped galvanisation and PVC-type coatings. Care must be taken when installing products with these coatings as any damage during installation and fitting, drilling and cutting etc. must be re-protected to ensure the integrity of the rest of the coating.

Hot-dipped galvanised products offer two forms of protection as the zinc coating protects the surface of the steel and becomes a sacrificial anode if damaged.

Non-metallic components

In highly corrosive environments, where metals are not suitable due to high levels of corrosion, non-metallic products are commonly being specified as an alternative. It is important to remember that plastics are not completely impervious to chemicals and often suffer from UV exposure, which should be taken into consideration when specifying project materials.

The possibility of corrosion may not be at the forefront of material specifications and in times of economic hardship, may be over looked. However, with the World Corrosion Organisation estimating the annual cost of corrosion, throughout all industries, at $2.2 trillion, it truly is a global issue. We believe any short-term savings made from overlooking the extensive effects of corrosion will be more costly in the future and the figure from the WCO backs this up.

If you are concerned about potentially corrosive environments affecting products you may be specifying, we are able to offer expert advice on the best product to suit your specific requirement.

Have you had any experience with corrosion and would like to share your experiences then please leave a comment below. Learn more about our offer of electrical lugs.

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In recent years there has been a large influx of European switchgear. This has often lead to confusion about the type of switchgear being used and the switchgear bushing to which the cables are to be terminated.

Correct cable terminations

This has led to the discovery of conventional heat shrink terminations being used incorrectly in instances where the bushings were compatible with CENELEC style separable connectors, E.g. Pfisterer CONNEX and Euromold connectors. This can lead to delays on site in sourcing the correct cable termination type, not to mention the practical difficulties and increased costs in re-terminating the cables.

Specify the correct equipment

One of the ways to avoid this issue is to cross check the cable termination specified with a database of equipment manufacturers, ensuring that the termination type sourced is completely suitable for your switchgear bushing. This can be a lengthy process if the relevant information isn’t readily available.

Therefore, ETS Cable Components are able to offer this service using our expansive database of switchgear and bushing equipment and equipment manufacturers to insure the correct equipment is matched at tender stage.

The advantages of this bushing selection service being:

• Correct costs for termination materials.
• Compatibility with the cables being used.
• Accurate installation costs.
• Reduction in lost time on site.
• Happier clients!

Switchgear Familiarisation Training

Additionally, we are able to offer familiarisation training for your installation team, on-site support and the technical expertise you would expect from one of the UK’s leading cable accessory distributors.

Please contact Nick Timms for more information on sourcing the correct terminations and connectors.

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