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Monthly Archives: April 2014

  • Why Choose An Exothermically Bonded Connection?

    Exothermically welded connections and mechanical connections are very similar in their applications, yet their performance can differ greatly.

    As UK distributors of ERICO CADWELD welding systems, we explore the benefits of a exothermic bonded connection over mechanical connectors.

    The CADWELD Weld

    - Will carry more current than the conductor.
    - Will not deteriorate with age.
    - Is a molecular bond that eliminates any risk of loosening or corrosion.
    - Will resist repeated faulty currents.
    - Can be quality controlled simply by visual inspection.

    Reliability

    As the molecular bond eliminates the concept of surface contact, an electrolyte cannot penetrate between the conductors and cause oxidation and deterioration in the course of time.

    Corrosive Environments

    This reliability is of particular interest for humid or chemical environments or for bonds directly buried in the ground.

    Ability To Withstand High Current

    The melting temperature of CADWELD filler material is higher than the melting temperature of copper (1082oC). For this reason, in the event of abnormal heating due to a high fault current, the conductor is destroyed before the connection.

    Conductivity

    The CADWELD connections form a solid bond around the conductors assuring continuity. The cross sectional area of the weld has greater current carrying capacity than the conductors.

    Performance

    Standard CADWELD welds have a cross section greater than that of the conductors to be joined, which compensates for the difference in resistivity between the conductor and the welding material. Consequently, under fault conditions, the weld will always remain cooler than the conductor.

    If special applications do not allow for the required increase in cross section to be employed, the use of the formula:

    CADWELD resistivity formula

    Which will make it possible to define precisely the resistance of the CADWELD weld.

    Comparison between CADWELD bonded connections and mechanical connections

    CADWELD Weld Mechanical Crimped Connection
    cadweld weld

    mechanical crimp connectionActual Contact Surface
    Mechanical crimping connection points of contact

    The CADWELD bonded connection provides permanent conductivity over the whole of the section due to a molecular bonding between the metal surfaces. The mechanical connection presents a significant difference between the apparent contact surface and the actual surface.


    Exothermic Welding Video Playlist

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  • Q&A: Maintaining an IP66 seal throughout a cable gland connection and equipment entry

    Question:

    I need to install a brass CW gland into an IP66 enclosure, however I need to ensure the IP rating is maintained throughout the cable connection and equipment entry. How is this done?

    Answer:

    All cable glands are supplied with an IP (ingress protection) rating, which refers to the level of sealing effectiveness as defined in IEC 60529 (Formerly BS EN 60529:1992).

    It is important to note that the IP rating of a cable gland relates to the outer seal of the cable gland, where the cable itself is connected to the gland. 

    maintaining an IP66 seal throughout cable gland equipment entry

    The IP rating supplied with the gland, usually does not related to the protection offered to the equipment or enclosure entry. Even if the enclosure itself is, for example, IP66 rated, most glands will only provide protection to IP54.

    Where this is the case, a nylon washer (also known as an entry thread washer) should be installed between the cable gland and the equipment entry, as per the diagram above. The addition of a nylon washer, or red fibre washer for Hazardous Areas, increases the ingress protection to IP66.

    Although there are gland types that come supplied with entry thread washers, it is important to check individual cable gland design for more information regarding outer seal and equipment entry Ingress Protection ratings.

    If you're unsure, please contact a member of our Sales Team and we'll be happy to advise you on the correct cable gland and IP rating for your requirements.

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  • Reducing The Risk From Underground Electrical Cables

    Burying electricity cables is common practice when laying cables within urbanised areas. Placing the direct-buried cables underground reduces disruption during construction and lowers the risk to members of the public. However, it does provide a number of risks for future excavation and third party digging.

    In 2010, the dangers of not correctly marking or tiling buried electrical cable were unfortunately brought to light when a construction worker received severe burns to his face, neck and arms after the tip of the ground breaker he was using pierced through a 11kV cable buried around 80cm underground. The tool tip vaporised in a surge of at least 1 million watts causing injury to the worker.

    Even recently, in March 2014, a digger bucket came into contact with a 20kV underground electric cable during excavation works in front of a newly built substation. Fortunately both workers avoided injury, but it was a serious enough incident that is sparked a HSE investigation. Andrea Robbins, HSE investigator of the case digger case, stated:

    “The construction industry needs to be more aware of the dangers of working in the vicinity of live underground services.”

    “Appropriate planning and control measures should always be in place. A failure to do so could result in inadvertent contact with the live cables, the consequences of which can be fatal.”

    The dangers of burred cables are well known throughout the industry and products have been developed to reduce the risk to workers unknowingly disrupting electricity supply and risking injury or death. ETS provide a number of different buried cable marking and tiling products from concrete tiles to heavy duty 60micron thick plastic tape tile to aid with the identification of underground cables.

    Our vast range of products provide a number of different advantages, not least protecting and reducing the risk of injury and loss of life. Correctly marking cables can help reduce the risk of loss of power supply for end users and tiled cables can improve the impact resistance of the cable to reduce damage during localised digging and disruption.

    Using cable markers to identify and protect underground electrical cables offer a significant cost benefit when compared to the time and cost of replacing damaged or severed sections of the cable.

    We also supply a traceable underground warning tape which features two stainless steel wires running through it to enable detection by metal detectors prior to any digging, enabling any alterations to be made before work begins.

    Ultimately, taking precautions when burying cable can help save time and money during future projects and it could even safe someone’s life.

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  • Ellis Innovation Delivers HV Cabling Solution for Siemens

    The world’s leading cable cleat manufacturer, Ellis has underlined the reason for its industry standing by designing an entirely new product in response to a cabling requirement from one of the biggest names in global business, Siemens.

    The product is a two-in-one cable guide and clamp that was developed by Ellis following a call to assist in the installation, and subsequent restraining, of seven large diameter high voltage (HV) cables for an offshore electrical substation that forms part of the multi-million pound HelWin 2 project.

    “The requirement was to feed seven 117mm diameter cables along a specified route within a fabricated structure, which featured a significant number of twists and turns,” said Ellis’ managing director, Richard Shaw.

    “The problem though was that there was no existing product that would enable the cables to be installed in an efficient, safe and cost-effective manner.”

    The Ellis team, which had previously developed a roller-system for installation of HV cables in power tunnels, took stock of the situation and set to work developing a solution that would secure the Siemens specification, and see them become the first company in the world to offer a two-in-one cable guide and clamp.

    “Within six weeks of the initial meeting, Siemens had approved our new product design, two weeks later five working prototypes successfully passed an installation trial in Germany and less than a month after that we’d received the order and had the tooling ready for mass production,” added Richard.

    Ellis’ new cable guide and clamp works in two stages. Firstly the cables are guided by it into their final location, while trumpeted entry and exit points ensure the cable is not damaged when fed through particularly sharp angled turns. Once the cable is laid correctly, the top half of the clamp is removed, a fixing piece installed directly onto the cable and the top half re-secured, thus turning the guide into a fully-functioning HV cable clamp.

    Siemens Helwin 2 Project

    “We have always taken great pride in our ability to innovate, but to be asked to do so in a live project situation was certainly a real test of our mettle,” continued Richard.

    “To come through such a test with Siemens problem solved, the specification secured and an entirely new product range on the verge of being launched is the kind of result that even I, at my most optimistic, wouldn’t have predicted when we sat in that first meeting looking at the requirements of the project.”

    HelWin 2 is a 690MW offshore HVDC platform that provides low-loss transmission between the North Sea offshore wind farm, Amrumbank West and Germany’s onshore grid. It is due to be operational in 2015.

    Ellis' new range of two-in-one cable guides and clamps will be launched in spring 2014.

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