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A Guide to Medium Voltage Cables

Cable basics, Cable selection, Keystone Academy /

  Medium Voltage (MV) are power cables widely used in commercial, industrial, and electrical utility applications. At Keystone, our MV cables have a voltage rating from 6kV to 30kV. In this blog, we will discuss the construction of MV cables and explain how each layer contributes to their overall functionality. Construction of a MV Cable ConductorThere are 2 types of conductors that we use for the construction of our MV cables: Copper and Aluminium. Copper: Made from electrolytic copper with a purity exceeding 99.95%. Aluminium: Drawn from aluminium ingots with a minimum purity of 99.70%. Conductor ScreenOur conductor screen is an extruded cross-linked semi-conducting compound that covers the metallic conductor. This layer acts as a stress point in the insulation, potentially weakening its long-term durability. Insulation ScreenThe insulation screen is a cross-linked semi-conducting compound extruded over the insulation. It provides a smooth surface, serving as a transition material between the insulation where an electric field exists and the conductive metallic screen, where the electric field is zero. Thus, this reduces the stress at the insulation layer. Metallic ScreenThe metallic screen typically consists of a layer of helically applied copper tape with an overlap, over the insulation screen. The metallic screen in a 3-Core cable ensure that the electric field remains contained within the cable core. Cable Assembly (Optional)For 3-Core cables, identification taoes (Brown, Black, Grey) are placed under the metallic screen before the cores are laid up. A non-hygroscopic polypropylene filler is applied between the laid-up cores to provide a circular shape for the overall cable. Polypropylene tape(s) or PETP (Polyester) tape(s) is used as a barrier tape over the laid-up cores. Separation Sheath (Optional)All armoured cables include an extruded layer of Black PVC [1], MDPE [2], or LSZH [3] separation sheath, applied over the core or laid-up cores to prevent corrosion by separating different metals and avoiding galvanic effects. Armour (Optional)In armoured cables, the armour is applied over a separation sheath for additional mechanical protection. Single-core cables use aluminium wires (AWA), double aluminium tape armour (DATA), while multi-core cables use galvanised steel wire armour (SWA), or double galvanised steel tape armour (DSTA). Outer SheathAll cables have an extruded layer of PVC [1], MDPE [2], or LSZH [3] outer sheath over the core, laid-up core, or the armour. This outsheath, usually black, protects the cables from sunlight and termites. Another colour may also be provided upon agreement between the manufacturer and purchaser. [1] Polyvinyl Chloride[2] Medium Density Polyethylene[3] Low Smoke Zero Halogen For more information, check out our Medium Voltage Cables catalogue. Download Catalogue Keystone’s Commitment to Our Clients We are committed to providing exceptional customer satisfaction for our clients through a quality management system. Our experienced and highly skilled inspectors ensure that newly manufactured MV Cables are tested in a clean dust-free room environment and that each cable meets international standards such as IEC 60502-2 and BS 6622. For any enquiries regarding Keystone’s MV Cables, please check in with our sales team. Contact Sales

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Selection Guide for the Right Signal Cable

Cable selection, Keystone Academy /

In our previous Keystone Academy blog, “RS485 vs RS422”, we introduced the similarities and differences between the 2 wire protocols, RS485 and RS422. Though similar, the 2 wire protocols are not the same. After knowing their differences, you may be wondering how to select a suitable signal cable. Here, we have distilled the key considerations to look into: Insulation Insulation prevents electrical losses. There are 3 types of plastic insulation, namely Polypropylene (PP), Polyethylene (PE), and Polyvinyl Chloride (PVC). The table below shows a comparison of the 3 materials, although PVC is still the most commonly used.  Screening Screening prevents noise interference such as Electromagnetic Interference (EMI). Data communication cables are usually twisted to screen out noises. In addition to this cable laying method, Keystone adds screen(s) to the cables as a physical measure to further prevent noise interference. There are 2 frequently used screens; the foil screen and the tinned* copper wire braid with foil screen.   Foil screens are used in normal circumstances while tinned copper wire braids with foil screens are used when the environment is extremely noisy. For instance, at industrial plants and factories with many motors running at the background.  *Copper is tinned to provide additional protection against oxidation and corrosion. For more information about other cables with foil screens and cables with tinned copper wire braid with foil screens, check out the details in our Smart City catalogue.

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Understanding Variable Speed Drive Cables

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Power and control cables transmit and distribute electrical energy in various applications. In cases where Electromagnetic Compatibility (EMC) is required, Variable Speed Drive (VSD) cables become an attractive choice. What are VSD Cables? VSD cables are 3-core cables specially designed to limit the effects of Electromagnetic Interference (EMI). They are screened, heavy-duty cables for machinery that requires speed control.  They are used in control and motor systems supply in industrial water pumps, conveyor systems, textile machines, cranes, and paper industries. Symmetrical Design VSD cables are designed symmetrically, where 3 earth conductors are situated in the interstices of the 3 phase conductors. This enables us to achieve a minimal ground current, reducing the chances of bearing fluting and thus preventing motor bearing failure. Keystone Cable’s VSD Cables Our VSD cables have been selected for iconic projects in Singapore and Australia, such as the Jurong Island Desalination Plant in Singapore, Amazon Data Centre in Singapore, and overseas, such as BHP Billiton – Macedon in Australia. We have a strong cable specialist technical team to provide recommendations for your projects. Please contact us should you require more information. Contact Sales

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H07RN-F Neoprene Cables: For Heavy Duty Use

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Power cables are ubiquitous for different industrial applications. In cases where ordinary power cables cannot operate under certain harsher conditions, H07RN-F neoprene cables become an attractive choice. What does H07RN-F mean? H – conformity to harmonized standards (set by CENELEC that standardizes electrotechnical specifications)07 – voltage rating is 450/750VR – EPR insulationN – PCP jacketF – Flexible copper conductors H07RN-F neoprene has the following properties that make it a good heavy-duty electrical cable: Flexible In addition to the rubber properties, which give it good flexibility, neoprene cables also use Class 5 copper conductors, which indicate finer copper strands to make up the conductor core. This prevents the cable with high flexibility properties and allows neoprene cables to be installed either as a fixed or mobile cable. Chemical Resistance The cables have great chemical resistance and thus can be installed under adverse conditions such as oily, acidic, and alkaline environments. Scratch Resistance Neoprene has superior resistance to abrasions and scratches. Therefore, they are suitable and commonly used at worksites. Wide Temperature Range Compared to standard PVC insulated cables, which have a temperature rating of 5°C to 70°C, neoprene cables have a larger range of temperature rating of -25°C to 90°C; under high-temperature conditions, the neoprene cable insulation will not melt, and at low-temperature conditions, neoprene cables can still maintain its flexibility and not crack. It is thus a popular choice for use under environmental hazards, including water, sunlight, sand, and snow. Given the distinct advantages of neoprene cables, they are popular for industrial use and use in worksite equipment such as power tools, pumps and generators.  For more information on how EPR insulation may compare with other common cable materials, we have a summarized table for reference. Certified Neoprene Cables Given the heavy-duty use of such cables, selecting a brand where the neoprene cables have been certified is important. Keystone Cable’s neoprene cables are certified by VDE, a German third-party organization in standardization, testing and certifications. Our neoprene cables have been selected for use in iconic projects such as Amazon Data Centre, Singapore MRT, Jurong Port, Sengkang General Hospital, and Singapore F1. We have a strong cable specialist technical team to provide recommendations for your projects. Contact us should you require more information.

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Solar Cables Construction and Specifications

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In search of a clean and sustainable energy source for the future, solar remains the most promising renewable energy source for Singapore and most Southeast Asian countries. Singapore aims to harness 1.5 gigawatt-peak (GWp) of solar energy by 2025 and will accelerate the country’s goal to at least 2GWp of solar power by 2030. As a result, there is an increasing demand for Solar PV systems: solar modules, inverters, substructures, plugs, fuses, terminal boxes, and solar cables. In response to the rapidly growing demand of the solar industry, at Keystone, we play our part in contributing to renewable energy sources by providing high-quality Keystone photovoltaic cables that meet stringent requirements. A solar cable is used in photovoltaic power generation. Solar cables are designed to be UV- and weather-resistant and can be used within a wide temperature range for indoor and outdoor applications. Solar Cable Construction Keystone solar cables are double-insulated with cross-linked polyolefin (XLPO). Compared to common power cable insulations such as PVC and XLPE, XLPO has a higher nominal temperature rating of -40°C to 120°C. XLPO insulation has excellent UV resistance, flame retardancy, chemical resistance, and durability. In addition, XLPO is halogen-free, meaning it will not emit toxic gases when exposed to fire. Using poor-quality solar cables may reduce the lifespan of entire solar PV installations, whereas high-quality solar cables prevent pre-mature ageing processes when installed under appropriate guidelines. To ensure the quality of the solar cables, Keystone solar cables are manufactured in accordance with EN 50618 (H1Z2Z2-K) and certified by TÜV Rheinland. EN 50618:2014 consists of a series of stringent tests for cables used in PV systems, which include electrical properties test, constructional and dimensional test, insulation and sheathing material test, cold impact and cold bending test, ozone resistance test, weather/UV resistance test on the sheath, dynamic penetration test, damp heat test, shrinkage test, vertical flame propagation and smoke test. The entire testing process is extensive to ensure the quality and reliability of the solar cables. Keystone solar cables are reliable for the entire solar PV system lifespan as they have a service life of more than 25 years under normal use with proper installation. Here are some installation tips we have gathered to ensure a good solar cable lifespan: Avoid using installation bundles with many cables, as this could raise the ambient temperature of the cables and cause derating. Avoid having cables completely exposed to the weather and laid haphazardly or transversely. Avoid laying cables in the rain gutter. Pay attention to clamped points or cables that lean over sharp edges to prevent damage to the sheath or insulation. Do adhere to the minimum cable bending radius. For instance, please do not install the solar cables in a tight loop formation, as it would likely exceed the bending radius. As solar cables are important to the entire PV system, Keystone technical team can help provide professional guidance on choosing the most appropriate solar cables for your installation. Our solar cables have been selected for large solar farms in Singapore, Indonesia and Vietnam, such as Singapore Solar Nova HDB Rooftop solar project(25Mw), JTC Jurong Island Solar Farm in Singapore, Trung Nam Solar Power Plant(200Mw), Tra Vinh Solar Power Plant(95Mw) in Vietnam and Gangga Island Resort and Spa Solar project in Indonesia. To learn more about Keystone’s solar cables, please contact our team. Contact Sales

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Selection Guide for the Right Ethernet / LAN Cable

Cable selection, Keystone Academy /

Whether getting a LAN cable for home use or selecting a LAN cable while planning for industrial needs or business network infrastructure, you may have questions about which cable to use. You may notice several types to choose from, namely Cat 5, Cat 5e, Cat 6, Cat 6A, Cat 7, Cat 7A, and up to the latest Cat 8. The Cat ratings stand for the category, and the different numbers represent different speeds and specifications for each cable type. The higher the number, the newer the technology and the higher the data rate supported. The basic differences to look for across the categories would be : Maximum data rate (measured in megabits per second, Mbps or gigabits per second; Gbps) Bandwidth (measured in megahertz; MHz) Shielding (to protect against interference) To generalize, Cat 5 is mostly obsolete now as it only goes up to 100Mbps.  Cat 5e is suitable for installation in residences and small offices with network speeds below 1Gbps. It supports bandwidths from 100 MHz up to 350 MHz. An easy way to think of bandwidths would be similar to traffic flow; the wider the road or higher the bandwidth, the more cars or data can pass through at a go. In Cat 5e, the pairs are twisted together tighter than in Cat 5 to reduce crosstalk (the interference caused by electromagnetic signals affecting another electronic signal). Cat 6 is recommended for larger installations like University campuses and big office buildings. Cat 6 can support 1Gbps up to 100 meters and 10Gbps up to 55 meters. It supports bandwidths up to 500 MHz. The pairs are twisted even tighter than Cat 5e to help with crosstalk. Keystone Cable’s Cat 6 also has a spline between the pairs to minimize crosstalk. Cat 6 can be shielded to improve performance (earlier network cables were all unshielded). For example, an unshielded twisted pair cable would be satisfactory for a short run between a computer and router, but a foil-shielded cable is better for longer runs or where the cable would pass through areas of high electrical noise, such as in an industrial factory. At Keystone, our Cat 6 stock include U/UTP and F/UTP. Cat 6A is suitable for industrial, commercial, and data centre applications. Cat 6A handles 10Gbps up to 100 meters and supports up to 500 MHz bandwidth. The pairs are twisted tighter than Cat 6 to help with crosstalk and allow higher bandwidth. It is common to find each pair individually foil-shielded and with an overall braided shield. At Keystone, our Cat 6A stock include F/FTP and F/UTP. Cat 7 and Cat 7A are commonly found in bandwidth-intensive applications like data centres or other places where extra interference protection is needed. Cat 7 and Cat 7A handle 10Gbps up to 100 meters and support bandwidth up to 600 MHz. What helps this cable category perform better than the previous ones are more strict and precise manufacturing processes to increase the tightness of the twists, the individual shield and the overall shield to reduce crosstalk and interference dramatically. Cat 7 and Cat 7A have shown in test results to deliver 40 Gbps over distances up to 50 meters and 100 Gbps up to 15 meters. The one drawback of using Cat 7 or 7A may be that it is not recognized by EIA/TIA (wiring standards for commercial and telecommunications wiring) and uses its proprietary non-RJ45 connector, which may be more challenging to purchase. At Keystone, our Cat 7 stock includes S/FTP. Cat 8 is new and explored for use between servers and switches in large data centres with an insanely high bandwidth requirement. It is uncommon to use Cat 8, although it does jump several iterations in performance. It can handle 25Gbps/ 40Gbps up to 30 meters and supports bandwidth up to 2000 MHz. The development of Cat 8 is subdivided into Cat 8.1 and Cat 8.2 under IEC standards. Cat 8.1 is backwards compatible with Cat 6A, Cat 6 and Cat 5e, while Cat 8.2 is backwards compatible with Cat 7 and Cat 7A. This is due to the connector relationship where Cat. 8.1 uses a standard RJ45 while Cat 8.2 uses a non-RJ45 connector. As a rule of thumb, your network is only as fast as the slowest part of your entire channel. For example, if your internet connection is 300 Mbps but your router’s ports can transfer only 100 Mbps, then your whole network would be limited to 100 Mbps instead of 300 Mbps. Hence when you consider the Cat type, you may scrutinize the rest of your system to ensure compatibility. However, we recommend future-proofing, especially if you intend the cable installation to be concealed within walls. In such cases, we recommend getting a LAN cable one step higher than your current requirements to future-proof your installation. For more enquiries, please check in with our sales team. Contact Sales

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When do We Use Armoured Cables?

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What is the difference between unarmoured and armoured cables? As the name implies, an armoured cable has added protective armour that helps protect the cable core. This is important in places where there could be accidental damage to the cable due to mechanical stress or impact. To put it in context, typically, armoured cables would be used when you require the cable to be buried directly underground for outdoor installation or in tunnels. There may be instances where the ground is opened up again, and in the process, a spade or mechanical excavator may hit the buried cable by accident. In this case, the armour would help protect the cable conductor core from being exposed easily and prevent electric shocks and interruptions in power delivery. You may come across aluminium wire armour (AWA) or steel wire armour (SWA) for standard power cables. Steel is naturally a stronger material, but you will notice that single-core cables are ALWAYS paired with AWA and never SWA. This is because aluminium is non-magnetic. What is AWA vs SWA for armoured cables? If a single-core cable is paired with steel wire armour, a magnetic field will be induced when current flows through – the whole cable becomes a giant magnet. The higher the current, the larger the field. The magnetic field will induce an electric current (eddy current) in the steel, which would cause overheating and massive derating of the cable. Aluminium, due to its non-magnetic nature, would not cause this issue. However, once we move past single-core into two or more cores, it is safe to revert to galvanized steel wire armour because magnetic fields produced in such multi-core cables will have a cancelling out effect by the other cores’ fields thereby preventing the magnetic flux. Armoured cable construction This would be a typical armoured cable construction at Keystone: Conductor Class 2 stranded plain annealed copper Insulation Cross-linked polyethene (XLPE) is recommended over polyvinyl chloride (PVC) to provide a higher maximum operating temperature, better water resistance and stronger dielectric properties. Bedding A protective layer between the insulation and the armour. Armour Steel or aluminium armour to provide mechanical protection. Sheath  PVC or LSZH (Low Smoke Zero Halogen) outer sheath that holds the cable together. LSZH would be recommended for public areas or in tunnels. At Keystone, we would include UV stabilizers and anti-termite additives in our cable sheath material. Please check in on with our sales team for more information. Contact Sales

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PVC vs. XLPE: Comparison of Two Most Popular Cable Insulations

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Electric cable conductors must be isolated from other conductors and the environment to prevent short circuits. To do so, we extrude a layer of insulation around the conductor. Here, we examine Polyvinyl Chloride (PVC) and Crosslinked Polyethylene (XLPE), the two most common insulation materials used in the cable industry. Why PVC Insulation? PVC is the most widely used insulation material in power cables. This is because PVC insulated cable is:  1) A cost-effective material for electrical and physical protection for standard low-voltage building cables2) Has a small bending radius and is very easy to install in narrow places Applications for PVC cables include general low voltage cabling such as lighting and public building use.However, standard PVC has certain limitations: 1) Standard PVC has a maximum operating temperature of 70°C2) It is not as hardy a material when it comes to resistance to water and environmental stress cracking (ESC) When should you choose XLPE Insulation? XLPE has a maximum operating temperature of 90°C. This means that if we compared an XLPE insulated cable and a PVC insulated cable for the same conductor size, an XLPE insulated cable could carry a higher current load. This also means that based on your current load requirements, there may be instances where you would be able to select a smaller cable size if you used an XLPE insulated instead of a PVC insulated cable. XLPE is a hardier material compared to PVC due to the cross-linking process. XLPE provides greater tensile strength, elongation and impact resistances compared with PVC. This cross-linking process also enhances the material’s resistance to oil and chemicals even at elevated temperature; this makes XLPE a popular pick as insulation for LSZH Flame Retardant or Fire Resistant cables. Applications for XLPE insulated cables are therefore popular as main risers in buildings, LSZH flame retardant and fire resistant cables, as well as beyond low voltage applications such as medium to extra high voltage. The table below shows a simple comparison of the properties of these materials. Speak with our sales if you would like more information on what to choose for your requirements. Contact Sales

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