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Monthly Archives: September 2013

  • Using a 3M STFF Joint Sleeve within Section 12 areas of the LU Network

    To allow compliance with the LUL fire regulation standards, all joints for use within Section 12 of the London Underground Network must comply with the LUL 1-085 standard.

    To enable compliance for joints required in Section 12 areas, 3M developed a universal joint protection system to manage this. It is known as the Smoke, Toxicity, Fire and Fume joint sleeve or STFF for short.

    Installation of the STFF sleeve

    The sleeve is slipped onto one of the cables ready to be joined and parked back along the cable. The joint is made off in the normal way and the STFF sleeve is now slid over the joint and held in place by two stainless steel cable ties, one at each end.

    3m stff joint shield with steel tie 3m stff joint sleeve with steel tie closed
    LUL approved HellermannTyton MBT-type stainless steel cable ties should be used to secure the joint sleeve over the joint. A MK9-SST tensioning tool can also be used to achieve maximum tension on the ties.

    There are a number of variants of the STFF shield, including a sleeve design for joints or with a closed end, suitable for cable abandonment applications. A retrofit wrap around version can also be supplied if the joint has already been installed.

    Suitable LUL Section 12 and Hazardous Area applications

    Designed for use with all single or multi core HV and LV cable joints as well as cable abandonment applications, the STFF joint sleeve is approved on the LUL register (Register Number 1106) for use with 3M Cold Shrink jointing systems.

    The joint protection sleeve has applications for jointing on LUL projects as well as other hazardous and petrochemical applications, both on and off-shore.

    The 3M joint sleeve can only be purchased with the appropriate joint and is not available as a separate item.

    For more information on the 3M STFF sleeves applications, prices and availability, please contact our Sales Team.

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  • ETS Support The Alzheimer's Society's Memory Walk

    The staff from our Midlands Project Office volunteered in the local Alzheimer's Society Memory Walk which took place at Cannock Chase last weekend. Their role consisted of helping to organise the day as well as marshalling the route.

    The society organises these sponsored walks throughout the UK as a way of raising much needed funds to help people living with Dementia and to help research into finding a cure.

    Hundreds of people turned up for the walk, including TalkSport's Rupert Bell. The event went off without a hitch and thousands of pounds were raised for the Alzheimer's charity.

    Here are a couple of images from the event (click to enlarge):

    For more information on the work they do please visit http://www.memorywalk.org.uk 

  • Cable Crimping - Best Practices - BS7609

    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.

     under-crimped-over-crimped-lugs Under Crimped LugUnder-Crimped-Lug-Cross
    Over Crimped Lugover crimped lug

     

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

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