This is one of the most comprehensive knowledge of cables and their accessories, if you are recently choosing quality cables and their accessories, then welcome to bookmark this article. As a professional cable team, ZMS Cables will take you through the cables and their accessories.
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All cables can be divided into bare conductors, insulated cables, heat-resistant cables, shielded cables, power cables, control cables, communication cables, radio frequency cables, and so on according to their applications.
Bare conductors include overhead insulated cables, aluminum alloy conductors, and so on.
The advantages of overhead conductors are so great that they can be said to be everywhere in the world today in almost every country.
This is because they have the ability to transmit electricity with ultra-high strength.
In addition to this, the good safety factor of the power supply system and the ease of erection and maintenance are also a few of the advantages that make it one of the most popular cables in the world.
Shielded cables are cables with one or more mutually insulated wires wrapped in a common conductive layer.
This common conductive layer is the shielding layer of the cable, which is generally composed of braided strands of copper or other metals, non-woven spiral winding of copper tape, or conductive polymer layer.
The shield can be wrapped inside the signal or power conductor, both ways to prevent electromagnetic noise interference.
There are several types of commonly available insulated cables:
Polyvinyl chloride insulated cables
Polyvinyl chloride insulated flexible cables
Nitrile polyvinyl chloride mixture insulated flexible wire
Rubber insulated cables
Agricultural underground directly buried aluminum core plastic insulated cable
Rubber Insulated Cotton Yarn Textile Flexible Wire
PVC insulated nylon sheathed cables
Polyvinyl chloride insulated flexible cables for power and lighting purposes
The insulation materials chosen for cables in different environments are as follows:
Polyvinyl chloride (PVC): inexpensive, easy to process, lightweight, good electrical properties, corrosion resistance, chemical stability, moisture resistance, non-flammable.
Thus, the low-voltage distribution lines, especially in the terminal circuit, are widely used as the basic insulation and sheath materials.
Cross-linked polyethylene (XLPE): good insulation, high current-carrying capacity, low dielectric loss, lightweight, corrosion-resistant, moisture-resistant, cold-resistant, halogen-free, and does not emit large amounts of toxic fumes when burned.
Ethylene Propylene Rubber (EPR): cross-linked ethylene-propylene rubber, high flow-carrying, halogen-free, will not emit a lot of smoke when burning.
It also has flame-retardant properties and ozone-resistant stability and can be used in low-temperature environments of -50℃.
Cable trays are usually used for the overhead laying of power cables and control cables indoors and outdoors in industrial and mining enterprises.
It can also be used for telecommunication, radio television, and other parts of indoor and outdoor erection.
Cable Glands.
Cable Lugs.
Plugs and Connectors.
Cable Markers.
Wire Tools.
Cable Cleats.
Wire Conduit.
Cable Ties.
Cable Terminals
Wire Sleeving
Connecting the conductor between two cables, insulation shielding, and maintenance layer of the equipment, so that the cable line connection, is known as cable intermediate joints.
Electrical main wiring is a power plant or substation in the primary electrical equipment. And bus connection method, including the main bus and plant power system according to certain functional needs of the connection method.
The selection of power cables should comply with the following guidelines:
(1) The rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point.
(2) The continuous allowable current of the cable should be equal to or greater than the maximum continuous current of the supply load.
(3) The cross-section of the wire core should meet the needs of the stability of the power supply system in the event of a short circuit.
(4) According to the length of the cable check whether the voltage drop is in line with the needs.
(5) The minimum short-circuit current at the end of the line should be able to make the maintenance equipment reliable action.
The cable fixture should be free of iron components constituting a closed magnetic circuit.
This is because when the cable core is through the current, in its surrounding magnetic lines of force, magnetic lines of force, and the size of the current through the core are directly proportional.
If the use of iron and other magnetic materials, based on electromagnetic induction can be seen. Will be in the iron pieces of eddy currents in the cable heating, or even burn the cable.
So do not use iron for single-core AC cable fixed fixtures.
The biggest feature of heat-shrinkable attachment is to replace the traditional stress cone with a stress tube.
It not only simplifies the construction process but also reduces the standard of the terminal of the connector, is easy to equip, saves time and labor, has superior performance, and saves metal.
Heat-shrinkable cable accessories set infusion type and dry pack type as a whole, mobilizing the interests of these two kinds of accessories.
The above is some basic knowledge about cables and their accessories.
As one of the most essential items in daily life and national infrastructure, cables contain more theoretical knowledge behind them.
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Chris Dodds - Thorne & Derrick Sales Marketing Manager
Major projects, new trains, bewildering technology: these are the big-ticket items that command everyone’s attention these days. And why wouldn’t they?
Who cares about the high-volume, low-cost bits and pieces that literally hold the railway together? Nuts, bolts, pins, clips, arms, brackets…
Politicians don’t cut ribbons at the installation of a cable cleat, but they might – conceivably – have to explain the havoc wreaked by one failing following an electrical big bang.
A single dodgy component can inflict disruption and embarrassment that’s wholly disproportionate to its size and cost, by a very significant factor.
With this in mind – as the magazine’s unofficial Analogue Correspondent (my heart was hewn from the earth by Victorian navvies) – I was despatched to Rillington in North Yorkshire to visit a company that’s been keeping cables in check for almost 60 years.
In parts, the experience proved surprisingly digital.
In case you’re unfamiliar with the term, a ‘cleat’ is used to secure LV MV HV electrical cables to a structure by installing them at intervals along the cables’ length. What could be simpler?
But there are a number of factors affecting its ability to fulfil that role safely and effectively, including environmental conditions, the materials used, performance in the case of fire or impact, resistance to corrosion and the cleat’s strength.
The latter is often determined using a mechanical tensile test; however, the results can prove misleading as the force is applied in a slow, controlled manner.
The electromagnetic forces in short-circuit conditions act almost instantaneously and oscillate in every direction, sometimes with destructive consequences.
A cable cleat is most likely to fail at peak current, about 0.01 seconds after the event starts; a breaker won’t have woken up by then.
So, the only reliable way of demonstrating that a cleat will withstand the resulting forces is to also conduct a short-circuit test – International Standard IEC provides a formula for calculating those forces between two conductors in a three-phase supply. Potentially, they can amount to several tonnes.
Restraining cables during a fault is a fundamental role of the cable cleat; it’s a means of protection as well as support. In order to withstand the applied forces, the optimum spacing between each cleat can be determined using a formula which takes account of the required loop strength and peak short-circuit current.
None of this is news to the specialist team at Ellis – formerly Ellis Patents – which boasts a skilled workforce of around 60, mostly residing in the towns and villages around Rillington.
The firm was founded by Arthur Ellis, who piloted more than 90 bombing missions for the RAF during the Second World War.
Back on civvy street, he trained as a plumber and set about manufacturing plastic pipe clips and cable clamps, with electricity boards as his major customers.
That was ; today the firm has an annual turnover of around £7 million.
The operation moved to its current site in , about a mile from the York-Scarborough line. Unfortunately, the village station had closed 44 years earlier. Following Arthur’s retirement in , the company was acquired by Chris Calvert – its current chairman – and fellow investors from Walkern Victoria Industries. It acquired EDL Cable Supports in and has since become a global force, offering one of the most comprehensive catalogues of cleats, clamps, hangers and associated peripherals to international clients and projects.
As you walk around, you get the sense of an open, collaborative culture and an engaged workforce. Innovation is encouraged and facilitated through ongoing – and sometimes speculative – investment in new kit. This is not a company that’s resting on its laurels, but neither are staff being driven to distraction. Managing Director Richard Shaw tells me they are encouraged to go home at the appointed time and not check their emails. One culprit habitually ignores the edict whilst another recycles redundant equipment to assist with his construction of a traction engine! This seems a happy place.
Vertical Integration
Unlike many competitors, Ellis is fully resourced in-house – not only designing its own products, but also building CAD models and subjecting them to finite element analysis. “This tells us where a component will break and under what force”, says Richard. “Then we can 3D-print it.
“We know the printed model is about 40 per cent of the strength of the real thing due to the difference in plastics so – when we test it – if it comes out at 40 per cent of the figure we were expecting, we know we’re on the right track. We can do all that work without ever making anything, but it gives us the exact volume of materials needed, how long it will take to manufacture and the price.”
Beyond that, Ellis’ capabilities extend to prototyping and tooling for die-cast and injection moulding. This creates enormous flexibility and an inventive mindset: when a client comes with a problem, ways and means are readily available to develop custom-made solutions.
Through the 37 miles of tunnel on High Speed 1, there’s an Ellis cable cleat every 600mm. When the consulting engineer first approached the company during construction, he told them he needed 70,000 bespoke aluminium cleats in 12 weeks. They were designed, tested and delivered on time.
Ellis products are deeply embedded on the London Underground and Hong Kong Metro; they also formed part of the design for the recent installation of overhead line equipment through the Severn Tunnel. Thousands of its Centaur cleats can be found in the London Power Tunnels – extending for 20 miles under the capital – as part of the firm’s biggest ever order, worth £1.5 million. And the UK’s Astute-class nuclear-powered submarines also feature its cable clamp products.
Attention To Detail
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As we know, though, the railway is different; visit most of our classic tunnels and you’re unlikely to see many cleats. Instead, the approach taken since the advent of power, telecoms and signalling was to place the associated cables on hangers, fixed to the sidewall. It’s quick and makes life easy. But even here, there’s scope for improvement.
Stephen Walton, Ellis’ Technical Director, revealed: “We’ve reworked the traditional pressed-steel hanger to be stronger and safer by adopting a curved profile; they use less material so the shipping costs are cheaper. We’ve also developed polymer cable hangers which are lighter-weight, offer more insulation resistance and will never corrode.
“A lot of what we’re doing is about making the products easier to carry and improve speed of install, responding to the needs of the contractors we’re increasingly working with.”
When legacy hangers become life-expired, Ellis has a modular retrofit system which can be secured in place without disturbing the existing cable system. There’s a delightful simplicity and elegance about these products. I spent much of my chat time with Richard and Stephen fiddling with a stackable twist-to-fit no-bolts cleat, a unique device conceived in response to a Network Rail enquiry. The action had something very pleasing about it.
Inevitably, there is a procurement challenge here. Ellis’ polymeric products are more expensive than its metal variants, but being less heavy improves installation efficiency – a big issue for the rail industry given the scarcity of possession time – whilst their longevity means that whole-life costs are lower.
Cable cleats can be supplied pre-assembled with the requisite fixings – pushing up the initial purchase price but delivering benefits that reduce costs overall. Until we get our heads around these issues and learn to buy smarter, better products and lower expenditure will elude us.
All That Glitters…
represents another busy year for Ellis as it continues to grow the business. It has much to offer the rail sector through a sharp focus on innovation, responsiveness and value. Of course, its competitors would say the same thing – they have similar brochures, product ranges and part numbers. “Their ‘innovation’ is copying us,” Richard reflects ruefully.
It’s indicative of the company’s position in this market that others closely follow Ellis’ lead. However, whilst imitation is often flattering, it rarely compares favourably with the original.
By Graeme Bickerdyke
T&D are Specialist Distributors to UK Distribution Network Operators (DNO’s), NERS Registered Service Providers, ICP’s and HV Jointing Contractors of an extensive range of LV, MV & HV Jointing, Earthing, Substation & Electrical Eqpt – this includes 11kV/33kV/66kV joints, terminations and connectors for both DNO and private network applications.
Contact our UK Power Team for competitive quotations, fast delivery from stock and technical support or training on all LV-HV products.
Key Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV
➡ Read: Thorne & Derrick Announce Distribution Agreement & Contract With Nexans
uploaded by Chris Dodds - Sales & Marketing Manager (Thorne & Derrick International)
Front Line Defence Against Short Circuits
The below video produced by Ellis Patents shows the catastrophic outcome when multi-core cables attached to cable ladder using cable ties only are subjected to short circuit cable fault. Depending on fault levels cable cleats should be used to secure LV MV HV cables and to provide short circuit protection against disastrous cable faults, this includes the cable cleating of multi-core power cables.
Cable cleats are vital – cable ties alone cannot contain certain short circuit faults.
Depending upon the fault level rating of low and high voltage power cable installations cable cleats are essential short circuit protection devices.
Ellis Patents are global leaders in the innovation and manufacture of nylon, aluminium and stainless steel cable cleats – EP cleats and cable hangers satisfy the operational requirements of the construction, oil, gas, rail, utilities, wind energy and power generation industries.
Holding Power is Ellis Patents guarantee that EP Cable Cleats will contain dangerous short circuit forces – protecting your people, power and plant.
Ellis Patents are a leading voice in the campaign to have cable cleats reclassified as short-circuit protection devices. A move that would mean cable cleats would be placed on a parallel with fuses and circuit breakers.
“This reclassification makes absolute sense. In the event of a cable fault, the forces between cables reach their peak in the first quarter cycle, which is the point that cable cleats earn their crust. In contrast, circuit breakers typically interrupt the fault after 3 or even 5 cycles by which time, if the cable cleats are underspecified, the cables will no longer be secure, but will be putting vital electrical installations and lives at unnecessary risk,” says Paul Nolan (former) UK Sales Manager, Ellis Patents.
Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.
THORNE & DERRICK Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV
uploaded by Chris Dodds - Thorne & Derrick Sales/Marketing Manager
Thorne & Derrick Internatonal, based in the UK, are an Ellis Patents distributor for their market-leading and innovative range of cable cleats manufactured in the UK.
Ellis Patents are global leaders in the innovation and manufacture of nylon cable cleats, aluminium cable cleats and stainless steel cable cleats – Ellis satisfy the operational requirements of the construction, oil, gas, rail, utilities, wind energy and power generation industries.
Holding Power is Ellis Patents guarantee that EP Cable Cleats will contain dangerous short circuit forces – protecting your people, power and plant.
Without Fail – specify Ellis cable cleats for short-circuit protection of LV MV HV cables.
Q1 – Is there a recognised cable cleat standard to guide the electrical industry in the selection and specification of cable cleats?
A1 – International Cable Cleat Standard IEC: covers the testing and performance of short circuit cable cleats for low and high voltage cable support.
Q2 – What are the key factors in determining the correct cable cleat selection?
A2 – Environment, mounting structure, cable specification, cable configuration, peak short circuit fault level and outside cable diameter – this will enable effective specification of the cable cleat plus recommended cleat spacing.
Q3 – Can the correct cable cleat be specified based only upon the cross sectional area of the cable conductors?
A3 – No, the cable cleat retains around the outside diameter of the cable – see A2.
Q4 – I am confused but impressed by the level of customer choice with respect to triplex cable cleats. Why are there so many Ellis cleat options?
A4 – It is important that when selecting cable cleats for high voltage triplex cables that the cable cleats can handle the anticipated fault currents especially at working voltages of 11kV/33kV – also, different DNO’s specify different cleats.
➡ Triplex Cleats – Selection Guide for Cleating 11kV BS Part 4.10 Cables
Q5 – In order to retain high voltage power cables we require cable cleats with high fault rating but are concerned about potential outer cable sheath damage to “soft-sheathed” type power cables with EPR insulation. Typical oil rig application.
A5 – Specify and install Ellis Patents cable cleats with cushion liners – Ellis Emperor, Ellis Vulcan and Ellis Atlas cable cleats are all available with liners.
Q6 – Why do Ellis Patents manufacture cable cleats with liners?
A6 – Ellis cable cleats with built-in liners provide effective cushioning to cables during short circuit conditions.
Q7 – Can Ellis Patents support their technical specification with Video short circuit testing?
A7 – Yes, watch these Ellis Patents Videos on YouTube
Q8 – Why are cable cleats manufactured in stainless steel and aluminium?
A8 – Stainless steel and aluminium cable cleats are both non-magnetic and unaffected by magnetic fields surrounding low and high voltage power cables. Cables fixed with cable cleats made from magnetic materials would cause localised heating of cleated cables by the effects of induction.
Q9 – What is galvanic corrosion and how may it impact on cable cleat installations?
A9 – Read our cable cleats and galvanic corrosion Blog
Q10 – Can Ellis Patents provide technical advice on cable cleat considerations for multi-core cable installations?
A10 – Of course, here goes. As manufacturers of cable cleats, Ellis Patents are frequently asked for advice on the correct method of securing multi-core power cables.
We are not aware of any published data, which indicates any particular fixing method but custom and practice suggests that most users presume that any forces on the conductors, which arise in the event of a short circuit, will be restrained within the cable jacket and therefore cable cleats are not required.
The mechanisms within a multi-core cable, which help restrain the conductors in the event of a short circuit include:
1. The outer extruded jacket
2. The helical winding of the cores
3. Steel wire or other type of armour if present
In order to be able to provide meaningful advice Ellis Patents undertook a series of short circuit tests using 3 core, copper conductor, multi-core cables from various cable manufacturers.
Both armoured and unarmoured cables were tested across a variety of conductor sizes but because of the number of manufacturers and the variety of cable types and methods of construction available, it was not feasible to carry out exhaustive tests.
The results of the tests were varied but clearly showed that it is unsafe to presume that the forces between the conductors will always be restrained within the jacket of the cable, whether or not the cable is armoured or tightly helically wound.
Ellis Patents conclusion is that, unless the relevant cable manufacturer can give assurances regarding the performance of their specific cable at the anticipated fault level, fault rated cable cleats provide the safest option for securing multi-core cables.
Ellis Patents Ltd carry out a regular schedule of short-circuit tests.
If you are planning a project and would like certainty regarding the cable fixings for your installation (whether single or multi-core cables are included in the design) T&D and Ellis Patents would be interested to conduct a bespoke test, on your behalf, within our regular programme of work.
Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.
THORNE & DERRICK Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV
by Chris Dodds T&D - estimated reading time 5 minutes
T&D are Prysmian cable cleats stockists and distributors committed to supporting the correct installation of all BICON brand products – the following short post outlines the recommended installation procedure for Prysmian Multicleats which are specified to provide short-circuit containment of LV, MV and HV power cables.
Prysmian Multistrap is a stainless steel cable strap complete with a tensioning clip, securing pin and winding key – can be used for single, bundled or trefoil cleats including 11kV/33kV single core high voltage substation cables.
Multistraps are used as an intermediate cable restraint between Multicleats – positioned centrally between a pair of Multicleats to provide additional protection to medium/high voltage power cables in the event of a short-circuit.
The Multicleat cable cleats are commonly used to support and clamp 11kV/33kV power cables in industrial installations, hazardous areas and high voltage substations.
Aluminium cable cleats are also available for cleating cables onto containment in LV-HV substations and electrical building services where corrosion exposure levels are lower.
1. Fasten Prysmian BICON Multicleat base to cable support with M10 fixings. Loop Prysmian Multistrap through cable cleat base and around cables. Standard Duty Multicleats = 2 loops. Heavy Duty Multicleats = 3 loops.
2. Pull slack Prysmian Multistrap into outer loop. Insert split pin from right hand of Multicleat around outer layer of Multistrap about 10mm from end. Push plastic shear torque adaptor fully onto the end of the split pin and attach 13mm socket wrench. To tension the Prysmian Multistrap around the cables, rotating key anti-clockwise with the socket wrench until the adaptor shears.
3. Remove the shear torque adaptor and wrench. Swing the key over and engage in slots in clip.
The Prysmian Multicleat and Multistrap is correctly installed – compatible with most cable containment types including cable ladder and tray systems.
For further Multicleat & Multistrap technical specification, selection details and information see the following Slideshare.
To ensure sufficient cable support the Prysmian Multistrap MUST be used at the mid-point between Multicleats on all horizontal or vertical straight cable runs – here the Multicleats are shown cleating single core 33kV cables in trefoil arrangement however the strap-type cable cleats are suitable for single, multiple or bundled cable configurations.
Contact Thorne & Derrick for technical support or specification advice to ensure the correct cable cleat / cable strap arrangement according to the fault rating, installation application and environmental location.
Also from Prysmian ➡ Cable Joints | Cable Glands | Cable Cleats | MV HV Terminations Joints Connectors 11kV 33kV
LV ♦ MV ♦ HV
T&D distribute the most extensive range of LV, MV & HV Cable Jointing, Terminating, Pulling & Installation Equipment – we service UK and international clients working on underground cables, overhead lines, substations and electrical construction at LV, 11kV, 33kV and EHV transmission and distribution voltages.
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