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Cable basics

A Guide to Medium Voltage Cables

  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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Oil & Gas: Hazardous Area Classification

The oil and gas industry is hazardous as it is prone to explosions that occur in the presence of 3 substances: flammable gas or dust, oxygen, and an ignition source. Hence, to prevent explosions from occurring, we need to ensure that these 3 substances are not present at the same time. Conversely, as both flammable gas and dust are indispensable in the oil and gas industry, and oxygen is a necessity, the determining factor lies in the prevention of ignition sources. There are different types of hazardous areas and they are classified into zones based on their risk factors. Here we introduce the 3 different zones: Zone 0, Zone 1, and Zone 2. What are the different zones? The hazardous areas are classified into zones based on their likelihood and duration of occurrence of an explosive atmosphere. The zones are:  Zone 0: Explosive gas-air mixture is continously present, or present for long periods. Zone 1: Explosive gas-air mixture is likely to be present in normal operation. Zone 2: Explosive gas-air mixture is not likely to be present, or present for short periods. The different zones require dissimilar protection measures in terms of enclosure type, Zone 0 requires Ex ‘d’ protection, and Zones 1 and 2 requires Ex ‘e’ protection. Our Keystone Oil & Gas cables are structurally designed to fit their respective zones. Keystone Cable’s Oil & Gas Cables Keystone Cable has supplied Oil & Gas cables to iconic projects locally and internationally, such as Tanjong Bin Oil Terminal in Malaysia, Ilijan LNG in the Philippines, Jet Fuel Upgrade @ Yangon Airport in Myanmar, Pluto LNG in Australia, and the Arkema Project @ Jurong Island in Singapore. To find out more about our Oil & Gas cables, contact our Sales team. Contact Sales The oil and gas industry is hazardous as it is prone to explosions that occur in the presence of 3 substances: flammable gas or dust, oxygen, and an ignition source. Hence, to prevent explosions from occurring, we need to ensure that these 3 substances are not present at the same time. Conversely, as both flammable gas and dust are indispensable in the oile and gas industry, and oxygen is a necessity, the determining factor lies in the preventation of ignition sources. There are different types of hazarous areas and they are classified into zones based on their risk factors. Here we introduce the 3 different zones: Zone 0, Zone 1, and Zone 2. What are the different zones?   The hazardous areas are classified into zones based on their likelihood and duration of occurrence of an explosive atmosphere. The zones are: Zone 0: Explosive gas-air mixture is continously present, or present for long periods. Zone 1: Explosive gas-air mixture is likely to be present in normal operation. Zone 2: Explosive gas-air mixture is not likely to be present, or present for short periods. The different zones require dissimilar protection measures in terms of enclosure type, Zone 0 requires Ex ‘d’ protection, and Zones 1 and 2 requires Ex ‘e’ protection. Our Keystone Oil & Gas cables are structurally designed to fit their respective zones. Zone 0: Explosivie gas-mixture is continously present, or present for long periods. Zone 1: Explosive gas-mixture is likely to be present in normal operation. Zone 2: Explosive gas-air mixture is not likely to be present, or present for short periods. The different zones require dissimilar protection measures in terms of enclosure type, Zone 0 requires Ex ‘d’ protection, and Zones 1 and 2 requires Ex ‘e’ protection. Our Keystone Oil & Gas cables are structurally designed to fit their respective zones. Keystone’s Oil & Gas Cables Keystone Cable has supplied Oil & Gas cables to iconic projects locally and internationally, such as Tanjong Bin Oil Terminal (Malaysia), Ilijan LNG (the Philippines), Jet Fuel Upgrade @ Yangon Airport (Myanmar), Pluto LNG (Australia), and the Arkema Project @ Jurong Island (Singapore). To find out more about our Oil & Gas cables, contact our Sales team. Contact Sales

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RS485 vs RS422 Similarities and Differences

In data communication, there are low-frequency and high-frequency communication. For low-frequency data communication, 2 wire protocols are commonly used: RS422 and RS485. Wire protocols are guidelines for the transmission of data from point to point. Both of these “RS” protocols, RS422 and RS485, are also known as TIA-422-B, and TIA-485-A respectively. Cables following these protocols are robust and can transmit data to long distances and in noisy environment. However, as the distance increases, the speed of data transmission decreases. The distance can be calculated using the Baud Rate chart and the frequency of data transmission can be adjusted accordingly.  These low-frequency cables are generally used in sensors and devices that do not require high data speed. How are these protocols, RS422 and RS485, similar or different? Similarities Protocols RS422 and RS485 are similar in many ways. Some of their similarities are: 1. Both use differential signaling over twisted pairs. 2. Both can be made into full-duplex using 4 wires. 3. Both can transmit data up to 1.2km, at a rate of up to 10Mbps. Differences Though similar, the 2 protocols are not the same. RS485 is more advanced than RS422. RS485 is backward compatible while RS422 is not. In other words, systems following RS485 are RS422 compatible but systems following RS422 are not RS485 compatible. RS485 is convenient for multi-point interconnection and can be networked to form a distribution system that allows up to 32 drivers and 256 receivers. RS422, on the other hand, allows 1 driver and 10 receivers. Keystone Cable’s Signal Cables At Keystone, we supply cables such as UL2464 Single Pair Signal cables, UL2464 Multi Pair – OS Signal cables, and RS485 Multi Pair Double Overall Screened cables (sample construction below). These cables can be used for both RS422 and RS485.  RS485 Cable Construction Download Catalogue Download our Smart City catalogue to view the Keystone Signal Cables offered. For more enquiries, please contact us. Contact Sales

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Understanding Variable Speed Drive Cables

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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SS 299:2021 Updates – Fire Resistant Test Standard

In our previous Keystone Academy blog, ‘Fire resistant test standards-explained!‘. we introduced the differences among the 3 common LSZH FR test standards. In Singapore, Fire-resistant (FR) cables undergo tests given by the Singapore standard, SS 299. SS 299:2021 standards specifies the requirements of FR cables relating to characteristics required to maintain circuit integrity and the ability to reduce flame spread, emit low levels of smoke, and emit halogen-free gas during a fire. This is essential as it ensures that the power supply can be sustained so that life-saving electrical installations, such as fire alarms, smoke detectors, PA systems, and emergency lighting, can perform their functions even in the event of a fire. According to the updated Singapore FR Test standard (SS 299:2021), passing Protocols C, W, and Z is mandatory for FR cables to be fully compliant. Additionally, including other protocols, namely Protocols A, B, S, X, and Y from previous editions, is considered obsolete. This revised version was published on 23 September 2021. Fire-resistant tests: SS 299:2021 (from 23 September 2021 onwards) Fire-resistant tests: SS 299-1:1998 (before 2021) Resistant to fire alone (Category A, B, C, or S)OPTIONAL: Resistance to fire with water (Category W)This is meant to simulate fire in the presence of activated sprinkler systems. OPTIONAL: Resistance to fire with mechanical shock (Category X, Y, or Z)This is meant to simulate fire in the presence of disturbances such as falling debris. Check in with our sales team to learn more about how we can help you maintain circuit integrity while delivering energy or if you need further guidance on how the new regulation impacts your business. Contact Sales

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What are the different classes of cable conductors?

A cable conductor is the primary component of electrical cables. It refers to the metallic wire or wires that carry the electrical signal through the cable. Here, we examine the four different Copper (Cu) conductor categories: Class 1, Class 2, Class 5, and Class 6. Why are there different categories? The Cu conductors are grouped according to their flexibility; the higher the class, the more flexible it is. The flexibility of the Cu conductor of a cable will differ based on its unique purpose of use. The simplest conductor is a single, solid wire (Class 1). Although it offers a smaller cable in terms of diameter, the largest Cross-Sectional Area (CSA), and the purest signal, it is mechanically weak and is prone to breakage after a few cycles of bending. To improve flexibility, wires are stranded together. The more wires that are stranded together to make a given size, the more flexible the conductor will be. This implies that the higher the class, the more strands in the conductor. Furthermore, when wires are stranded together, they are much easier to bend and move during installation than a single wire with the same cross-section. Those in classes 1 and 2 are intended for use in cables for fixed installations. On the other hand, those in classes 5 and 6 are designed for use in flexible cables and cords but may also be used for fixed installations. The table below compares the different Cu conductors’ different categories. Contact us if you would like to find out more about the cable types to choose for your cabling requirement.

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H07RN-F Neoprene Cables: For Heavy Duty Use

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: FlexibleIn 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 ResistanceThe cables have great chemical resistance and thus can be installed under adverse conditions such as oily, acidic, and alkaline environments. Scratch ResistanceNeoprene 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. Contact Sales

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Solar Cables Construction and Specifications

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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