A Technical View of Medium Voltage Cables and Their Importance
A Technical View of Medium Voltage Cables and Their Importance
Nowadays, cables are available in three ranges-Low voltage, Medium voltage, and high voltage. Low voltage cables get rated for 2000v or less, medium voltage from 2000v to 35, 000v and high voltage cables are above 35,000v.
MV cables are usually preferred for power supply in mobile substation equipment, industrial settings, and mining to supply power to drills, shovels, haulers, etc. MV cables provide extra protection than low voltage cables due to their design and specifications.
What is a Medium Voltage Cable, its Design and Use
With the increase in the voltage range, new categories of cables were introduced in cables to classify them. The International Electrotechnical Commission (IEC) has classified cables with 1kV to 100kV as Medium Voltage cables. However, the voltage range of MV cables depends on the Country and the system used. Some medium voltages are 5000v, 8000v, 15,000v, 25,000v, and 35,000v.
Design of MV Cables
MV cables are often designed with extra protection to avoid the accumulation of charges at any point in the cable. The composition and design of MV cables include the following elements.
Conductor
MV cables use Class2 conductors made of electrolytic copper or high-purity electrolytic aluminum. The conductor is the central element of a cable that carries current.
Internal Semiconductor Screen
Internal semiconductor screen improves the electric field distribution on the conductor surface.
Insulation
Insulation can withstand a high electric field inside. The insulation material and its thickness define the maximum voltage that a cable can withstand. Several materials used for insulation are XLPE, High modulus ethylene propylene (HEPR), and Ethylene Propylene (EPR).
External Semiconductor
A peelable semiconductor is partially bonded to the insulation and helps prepare the connections easily.
Metal Screen
The metal screen is in contact with the external semiconductor and is made of copper fibers placed in a helix, uniformly covering the cable perimeter.
Water Protection
Cables with longitudinal seals have a hygroscopic material placed under the sheath to prevent the longitudinal propagation of water. And cables with double sealing have a series of hygroscopic wires placed on the conductor.
Inner Sheath
All armored cables have an inner sheath that acts as a separation cover between the metal screen and the armor.
Armour
The armor consists of metal wires or strips arranged on the inner sheath to improve cable protection against external aggression.
Outer Sheath
The material used for the Outer sheath is PVC and halogen-free polyolefins which protects the cable from mechanical and chemical aggression.
Application of MV Cables
MV cables ranging from 5Kv to 35Kv are preferable in substations, transformers, and medium voltage generator sets. The most common applications of MV cables are for
Different Types of Medium Voltage Power Cables
Different types of medium voltage cables are available in the 5Kv to 46Kv range. And most of these cables have one and three-conductor configurations. Each of these vary in size and design.
Shielded Cables
MV Shielded cables can meet stringent engineering standards and require special attention for proper handling and installation. The cable gets widely used in primary feeders in large complexes, facilities, and utility applications.
Shielded power cables can be single or three conductors. The cable includes an annealed, bare, solid, or concentric-stranded copper as a conductor that may be compact or compressed. The next layer is a semiconductor shield, insulation, and a semi-conducting insulation shield. The metallic shield is either gapped or lapped copper tape. Other types of metallic shield materials used are concentric wires and longitudinally corrugated copper tape. The outer jacket is PVC or PE.
Concentric Neutral Cables
Concentric Neutral cables are used in dry or wet locations and for various types of installations. These cables can be single or three conductors and have two major construction- Jacketed or Unjacketed. In these, Jacketed construction gets preferred.
The conductor for the cable is annealed, bare, and stranded copper. We can also use tin-coated wire and solid conductors. The concentric neutral conductor is bare or tin-coated copper wire applied helically over the insulation shield. These wires act as a metallic component of the shield and are neutral at the same time.
Paper-Insulated Lead-Covered (PILC) Cables
The application of PILC cables is for power distribution and industrial usage. We can install PILC cables exposed and in underground ducts or directly buried. They have annealed, bare copper conductors that may be round, concentric, compact stranded, compact sector, and in large sizes.
Cables with compact sector stranded conductors have insulated cable cores impregnated with a medium viscosity, polybutene-based compound. The liquid's excellent electrical and mechanical characteristics result in reliable and economical insulation. A seamless lead sheath alloy prevents moisture ingress. The outer jacketing is of PVC or PE.
Submarine Cables
Submarine cables are available in one or three conductors, and we can use them in dry or wet locations for various installations. The cable design contains annealed, bare, stranded copper but tin-coated wire and solid conductors are also available. These cables are XLPE, TR-XLPE, or EPR insulated, insulation shield, copper tape shield, lead-allot sheath, PE or PVC jacketing, and metal wire armoring.
Mining Cables
The types of cables used in mining include fixed mining cables and portable mining cables. Portable cables require flexibility and resistance to mechanical abrasion and damage. These cables are available in ratings up to 25 Kv and can have a maximum of 5 conductors.
Aluminum-Sheathed Cables
Aluminum-sheathed power cables get used for exposed and concealed wiring in wet and dry conditions. We can install these cables in ventilated, unventilated, and ladder-type cable troughs and ventilated flexible cableways. These cables have single, two, three, or four conductors. The conductors are bare, annealed, and compressed round-stranded copper. The insulated core gets enclosed in a liquid and vapor-tight solid corrugated aluminum sheath covered by a PVC jacket.
Reasons to Use Medium Voltage Cables Across Different Sectors
MV cables are preferable in various sectors for power distribution because of the following reasons.
Gloster Cables Manufactures MV Power Cables for Various Industrial and Domestic Applications
Gloster Cables is an established and leading wires and cables manufacturer for over two decades. The organization brings a range of power cables for industrial, commercial, and domestic applications. The MV cables manufactured by Gloster meet various industrial applications from a submarine, mining, and different industrial setting. Gloster manufactures MV HT XLPE cables, PVC and XLPE MV cables, submarine cables, mining cables, and aluminum sheathed cables of various MV ranges. The MV cables manufactured at Gloster adhere to quality system requirements to provide quality products.
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