uploaded by - Chris Dodds Thorne & Derrick Sales & Marketing Manager
âž¡ Thorne & Derrick stock a complete range of Earthing Spiders to provide portable earthing and short circuiting solutions for LV MV HV substation and overhead line applications – contact us for UK and Exports Sales of substation and transmission line portable earth leads. Largest European stocks of CATU Electrical.
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Information Courtesy: CA3C/2 Relating to General Requirements for 33kV Cable Jointing (Western Power Distribution)
MDPE stands for medium density polyethylene – this material is used principally as a cable sheathing material on larger size conductor cables with higher voltage ratings, such as BS6622 11kVÂ and 33kV power cables.
MDPE cable oversheaths must be removed from medium/high voltage cables with care using depth guarded jointers tools – incorrect use of tooling may cause damage to the underlying copper screen wires thus reducing the cross sectional area of the screen and its ability to carry fault current to which its designed.
Thickness of the oversheath should be of equal thickness at any point within the cable sheath of the MV HV power cable.
This may not always be the case and the use of specialised cable tooling may cause damage to the underlying copper screen wires, it is therefore, advisable to test on a scrap length of cable before jointing commences.
This applies to the installation of cable joints, terminations or connectors when using PG type cable stripping pliers manufactured by Alroc.
Removing Cable Sheath
Removal using the correct size of Alroc PG pliers according to the outside and overall diameter around the MDPE sheath.
Adjust the depth of cutting blade in accordance with the thickness of the MV HV cable oversheath, there is a depth variation of 1, 2 or 3; try the depth of cut on the end of the cable or on some spare core
Hold the Alroc PG pliers at 90° to the cable and place on the cable oversheath termination mark is, apply a slight pressure to the plier handle and rotate the Alroc pliers through 90°. This will create a full 360° circumferential cut in the oversheath of the 11kV/33kV cable
Note – excessive hand pressure on the handles of the Alroc pliers will result in copper wire screen damage. This will place a 360° circumferential cut in the oversheath
Remove and turn the stripping pliers so as they are parallel to the cable fit the cable between the support roller and cutting wheel
Ensure the cutting wheel is placed to the waste side of the circumferential cut, apply a good pressure to the plier handle and pull the pliers longitudinally towards the cable end
Using the claw blades at 90° to the cable, place the top blade into the cut line, apply pressure and pull down and away from the cut line, this will open the oversheath
Should you require any technical support or field demonstration of Jointing Tools to remove the sheath, screen or insulation from LV MV HV cables please do not hesitate to contact Thorne & Derrick.
Link Boxes For High Voltage Cable Systems | HV EHV 132kV | Transmission & Distribution
uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
HV Link Boxes & Bonding Leads
What Are Link Boxes?
Link boxes are installed on medium/high voltage power systems in conjunction with MV HV Cable Joints & Terminations incorporating a sheath break to prevent sheath circulating currents and limit induced voltage in the cable screen using bonded systems up to 132kV.
Underground cable bonding systems utilising 132kV XLPE insulated HV power cables are designed to provide cable sheath bonding to eliminate or reduce the circulating sheath currents and limit standing induced cable sheath voltages for safety reasons.
In an internal fault condition or short circuit of the high voltage power system the electricity current flows directly and safely to earth via the link box.
High voltage link boxes manufactured from corrosion resistant stainless steel (AISI 304L) are installed in association with cable joints to provide bonding of the HV cable circuit and at both circuit ends of the cable connected to the cable terminations – this product range complements our line of 132kV surge arresters with UK DNO and National Grid Approval.
Thorne & Derrick are Approved Suppliers for EMELEC, who offer an extensive range of electrical MV HV Link Boxes, expertly designed for bonding/grounding connections, made through removable links. We can provide excellent customer support, product selection and competitive prices with next-day delivery from extensive stocks of electrical Link Boxes.
Link Box Types
The standard ranges of single or 3 phase high voltage link boxes:
Wall / Gantry / Structure Type IP66 – 3 Phase & Single Phase, Single Bonding Link Box (Cable Termination & Joint Location)
Partial Discharge (PD) Type IP68 – 3 Phase Cross Bonding Link Box With SVLÂ (Cable Joint Location)
Pedestal Type IP66 – 3 Phase Earthing or Cross Bonding Link Box With SVL (Cable Termination & Joint Location)
Underground Type IP68 – 3 Phase Cross Bonding & Single Bonding Link Box With SVL (Cable Termination & Joint Location)
Underground Wall Type IP68 – 3 Phase & Single Phase Earthing Link Box With SVL (Cable Termination Location)
The link box is installed with cable joints and terminations to provide shield break accessibility for HV test purposes and to limit voltage build-up on the cable sheath – overvoltages on the sheath can be caused by fault currents, switching operations and lightning effects.
Multiple configurations are available – call to discuss your link box requirements up to 132kV
132kV
Single Phase & Three Phase Earthing Link Boxes
Thorne & Derrick can supply a complete range of 132kV Link Boxes in accordance with the Energy Networks Association (ENA) Engineering Recommendation C55/4 – ENA is responsible for maintaining the industry developed and published Technical Specifications (TS), Engineering Recommendations (ER) and Engineering Technical Reports (ETR).
ENA is the voice of the networks, representing the ‘wires and pipes’ transmission and distribution network operators for gas and electricity in the UK and Ireland.
The range of single phase and 3 phase High Voltage Link Boxes manufactured by EMELEC are ingress protected to IP66 or IP68 and suitable for indoor/outdoor wall mounting or underground direct burial – the internal connections/links are easily accessed and removed permitting disconnection of the individual sheaths for cable sheath fault testing.
Sheath testing is mandatory to ensure cable sheath integrity has not been compromised by cracks, cuts or snags during the cable pulling and laying installation.
A full set of Type Tests have been completed by the IPH Laboratory in Berlin including:
Internal Power Arc 40kA/0.1 second
Short Circuit 50kA/1.0 second
Lightning Impulse 40(60)kVp
DC Withstand 25kV/5 minute
Typical 132kV Cable Construction –Â IEC 60840
Link Box Routine Testing
All high voltage link boxes are factory tested before shipment to customer – applied tests include visual and dimensional inspection followed by electrical tests such as AC/DC Withstand Test, Insulation Resistance Measurement Test and Contact Resistance Measurement Test.
Link boxes are available with screen bonding options including:
Cross Bonding With SVL (Sheath Voltage Limiters)
Direct Earthing Without SVL
Earthing With SVL
Single Point Bonding With SVL
Surge Arresters & Sheath Voltage Limiters
Thorne & Derrick can also supply Sheath Voltage Limiters to suit the HV cable system bonding arrangement as well as Normal Bonding Leads, Concentric Bonding Leads and High Voltage Earthing Kits for connection between the link box and the cable accessory.
SVL’s are protective devices to limit induced voltages on the bonded cable system installation due to short circuits – SVL’s are installed between the metallic screen and ground inside the link box.
The screen separation of the power cable joints would be protected against potential damage inflicted by short circuit/break down. SVL rated voltages can be produced in accordance with client specification and the bonding system design requirements.
Bonding Cable Leads – Single v Concentric Leads
Bonding Leads
Single Core Bonding Leads | Concentric Bonding Leads
An integral component of a Specially Bonded System is the use of bonding leads with the correct physical and electrical properties for high voltage power cable system earthing – 120sqmm, 240sqmm, 300sqmm and 500sqmm single core and concentric type leads are available for use with 132kV link box installations in buried or gantry mounted applications.
The bonding system is critical for improving and stabilising current carrying capacity of the power system – Engineering Recommendation C55/4 describes in detail the cable specification, system design and installation for HV bonding leads.
Thorne & Derrick supply both normal and concentric bonding leads with conductor sizes from 120sqmm-500sqmm compliant with the physical and electrical specification established in Engineering Recommendation C55/4.
Fire retardant sheaths can be manufactured for tunnel or substation basement applications.
Common size bonding leads are generally available from stock.
Single Bonding of High Voltage Cables – the simplest form of special earth bonding consists in arranging for the cable sheaths of the three HV cables to be connected and bonded at one single point along the circuit length without cable joints and typically comprising shorter cable circuits. At all other points, a voltage will appear from sheath to ground that will be a maximum at the most distant point from earth bond. The high voltage cable sheaths must be adequately insulated from the ground – since there is opened sheath circuit (except through the SVL) current does not normally flow longitudinally along the cable sheaths and no sheath circulating current loss in incurred.
Single Bonding – Bonding Leads
Cross Bonding of High Voltage Cables – consists essentially in sectionalising the cable sheaths into minor sections and cross connecting them so as to approximately neutralise the total induced voltage in 3 consecutive sections as show below. Typically, the HV cables are sectionalised into 3 equal length sections and cross bonding is achieved within the link box.
Pictured: Typical layout of 132kV Joint Day design with location of link box pit and bonding cables positioned.
Cross Bonding – Bonding Leads
National Grid Type Registration
The full range of EMELEC Link Boxes have completed the National Grid Type Registration process. The Registration covers wall-mounted and buried link box types, across the voltage range 132kV – 400kV and is supported by authoritative test data from the IPH GmbH high voltage laboratories.
Globally, cable manufacturers and utilities specify and install EMELEC link boxes – recognising the proven consistent quality, durability and suitability of the HV EHV link boxes.
Link boxes are a critical component in any high voltage underground cable system, either for direct earthing or through Sheath Voltage Limiters and their reliability is essential for fully efficient operation including human safety. In the event of a system fault the short circuit current goes directly to earth through the link box in a controlled manner.
Contact Thorne & Derrick with link box and bonding lead sales enquiries for National Grid, UK DNO and IDNO project requirements.
Since 1985, T&D have developed a strong reputation for supplying UK DNO’s and NERS accredited Independent Connection Providers (ICPs) with an extensive range of LV MV HV Electrical Equipment including arc flash clothing and protection to utility workers.
T&D service UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.
PB Weirare the globally recognised designer, manufacturer and supplier of temporary portable earthing, voltage detectors and Buchholz Relays.
T&D met PB Weir following several recent project successes including supplying portable earthing systems to Hornsea Project 1, Scottish Power and a number of National Grid approved contractors working on projects at HV High Voltage and EHV Extra High Voltage.
Chris Dodds comments, “the commercial and technical support provided to Thorne & Derrick by PB Weir is excellent – in 2017 Thorne & Derrick experienced a record intake of new business, new customers and new account openings. That set the stage perfectly for 2018. Now our half-year sales targets and goals for 2018 have been met we look forward to introducing PB Weir to our existing and potential customers over the remainder of the year”.
Pictured left to right:Mick Fowler (PB Weir), Chris Dodds, Martin Wigham and David Tinning (T&D Sales Engineers).
Network Rail PADS Approced 25kV OLE Electrified Lines AC & DC Portable Earths
Transmission & Overhead Line Portable Earthing EHV 132kV 275kV 400kV
Westminster Voltage Detectors
Distribution Line Earthing Equipment
Buchholz Relays
âž¡ See how Thorne & Derrick working with PB Weir can supply standard and develop customer bespoke Portable Earthing Equipment for all substation earthing applications – this includes Line End Clamps, Earth End Clamps, Aluflex Leads, Operating Poles and Connectors.
Contact us for 3M Electrical, ABB, Alroc, AN Wallis, CATU Electrical, Cembre, Centriforce, CMP, CSD, Elastimold, Ellis Patents, Emtelle, Euromold, Filoform , Furse, Lucy Electric & Zodion, Nexans, Pfisterer, PB Weir, Polypipe, Prysmian, Roxtec, Sicame, WT Henley.
Invitation
Thorne & Derrick invite you to join LinkedIn’s largest LV-HV Electrical Discussion Group : Low & High Voltage Power, Cabling, Jointing & Electricals. Discussion subjects include cable installations, earthing, cable jointing, substation earthing, overhead line and electrical construction at LV, 11kV, 33kV and EHV. Network, engage and promote your profile, company or products with over 10,000 influencers.
Uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
Cembre RHU131-C
Thorne & Derrick International are Main UK Stockists and Suppliers of Cembre tools including crimping and cutting types for all constructions of LV MV HV cable including medium/high voltage 11kV/33kV power cables.
The following short article provides useful instructions about how to crimp aluminium conductor cables using Cembre model RHU131-CÂ presshead – with built in safety valve the tool with by-pass the oil supply when maximum pressure has been reached.
The following excerpts are taken from the Operating Manual of Cembre RHU131-C hydraulic presshead crimping tool – however this information applies to the following tool model variants Cembre RHU131.
Cembre RHU131-C hydraulic crimping head is suitable for installing the same range of cable lugs, crimp connectors and terminals as Cembre HT 131-UC
For competitive prices, stock availability and technical advice about the Cembre RHU131-C tool please do not hesitate to contact us.
Crimping Aluminium Cables
Hydraulic Crimping Presshead Accessories
Pre-Rounding Conductor (For Sectoral Cables)
Ensure all aluminium conductors are thoroughly cleaned using approved and suitable cable cleaning wipes prior to crimping.
From the table select the Cembre adaptors and pre-rounding dies for the appropriate conductor size.
Insert the upper adaptor Cembre AU130- and lower adaptor AC130–P into the head as per below.
Insert the pre-rounding die (94) into the AC130–P adaptor.
Position the conductor into the pre-rounding die (95) and locate the pre-rounding die (95) in the adaptor AU130.
Ensure that the pre-rounding die is correctly located in the adaptor with its upper slot in line with the internal adaptor pins.
Release the hydraulic pressure and remove the compacted round conductor.
Die Insertion
Connector Cable Crimping
Remove the pre-rounding dies and the adaptor AC130–P from the presshead.
From the table select the containing die and indentor recommended for the conductor size.
Insert the indentor into the ram (09).
Insert conductor into the connector.
Locate the connector into the containing Cembre die then locate the containing die in the adaptor.
Commence indent crimping from the barrel end for both splices and terminals following the sequence shown below:
For every operation ensure the die is correctly located in the adaptor with its upper slots in line with the internal adaptor pins
Each indenting operation is completed when indentor and die are fully closed; it is recommended to continue pumping until the maximum pressure valve is activated and a “click” is heard
Adaptor Fitting & Removal
Insert the upper adaptor AU130Â (98) into the U-fork head (14) until secured by the locators (15).To remove the adaptor from the U-fork head, push the adaptor from the locators and slide out
To insert the adaptor AC130–P(91), press the die release pin (12).
Insert the adaptor into the seat of the ram (09), until secured by the retaining pin (11). To facilitate this operation, an advancement of 3÷4 mm (0.11 – 0.16 in.) of the ram (09) is suggested. To remove the adaptor, press the die release pin (12) and slide the adaptor from the ram (09).
