Misplaced Pages

#626373

105-559: The main objective of CEITEC is to provide an incentive to the production of semiconductor components and microelectronics education . This project is part of the technology and industrial development policy of the federal Brazilian government. The initiative is a result of a partnership between governmental entities, universities , research centers and companies it is operating in a facility in Porto Alegre , state of Rio Grande do Sul . On 5 June 2021, president Jair Bolsonaro initiated

210-440: A current requires the flow of electrons, and semiconductors have their valence bands filled, preventing the entire flow of new electrons. Several developed techniques allow semiconducting materials to behave like conducting materials, such as doping or gating . These modifications have two outcomes: n-type and p-type . These refer to the excess or shortage of electrons, respectively. A balanced number of electrons would cause

315-439: A cut-off frequency of one cycle per second, too low for any practical applications, but an effective application of the available theory. At Bell Labs , William Shockley and A. Holden started investigating solid-state amplifiers in 1938. The first p–n junction in silicon was observed by Russell Ohl about 1941 when a specimen was found to be light-sensitive, with a sharp boundary between p-type impurity at one end and n-type at

420-481: A mass-production basis, which limited them to a number of specialised applications. High-voltage cable A high-voltage cable ( HV cable ), sometimes called a high-tension cable ( HT cable ), is a cable used for electric power transmission at high voltage . A cable includes a conductor and insulation . Cables are considered to be fully insulated. This means that they have a fully rated insulation system that will consist of insulation, semi-con layers, and

525-404: A porcelain or silicone insulator for outdoor use, or by contraptions to enter the cable into a power transformer under oil, or switchgear under gas pressure. Connecting two high-voltage cables with one another poses two main problems. First, the outer conducting layers in both cables must be terminated without causing a field concentration, as with the making of a cable terminal. Secondly,

630-513: A common semi-insulator is gallium arsenide . Some materials, such as titanium dioxide , can even be used as insulating materials for some applications, while being treated as wide-gap semiconductors for other applications. The partial filling of the states at the bottom of the conduction band can be understood as adding electrons to that band. The electrons do not stay indefinitely (due to the natural thermal recombination ) but they can move around for some time. The actual concentration of electrons

735-579: A company that was home grown and home funded to reach volume production at a world-class semiconductor manufacturing facility. This IC device is used for cattle tracking – essentially an electronic cow ID. Embedded in an ear ring, the chip can be read within a distance of 50 cm. The chip was designed entirely in Brazil and is competitively priced. This device is being manufactured at X-Fab Silicon Foundries in Germany. This company has been chosen by CEITEC to produce

840-423: A completely full valence band is inert, not conducting any current. If an electron is taken out of the valence band, then the trajectory that the electron would normally have taken is now missing its charge. For the purposes of electric current, this combination of the full valence band, minus the electron, can be converted into a picture of a completely empty band containing a positively charged particle that moves in

945-474: A current to flow throughout the material. Homojunctions occur when two differently doped semiconducting materials are joined. For example, a configuration could consist of p-doped and n-doped germanium . This results in an exchange of electrons and holes between the differently doped semiconducting materials. The n-doped germanium would have an excess of electrons, and the p-doped germanium would have an excess of holes. The transfer occurs until an equilibrium

1050-465: A few μm — is detrimental to the cable. Second, the insulation must be free of inclusions, cavities, or other defects of the same sort of size. Any defect of these types shortens the voltage life of the cable which is supposed to be in the order of 30 years or more. Cooperation between cable makers and manufacturers of materials has resulted in grades of XLPE with tight specifications. Most producers of XLPE-compound specify an "extra clean" grade where

1155-462: A field-free space must be created where the cut-down cable insulation and the connector of the two conductors safely can be accommodated. These problems were solved by NKF in Delft in 1965 by introducing a device called bi-manchet cuff. Figure 10 shows a photograph of the cross-section of such a device. At one side of this photograph, the contours of a high-voltage cable are drawn. Here red represents

SECTION 10

#1732869187627

1260-410: A guide to the construction of more capable and reliable devices. Alexander Graham Bell used the light-sensitive property of selenium to transmit sound over a beam of light in 1880. A working solar cell, of low efficiency, was constructed by Charles Fritts in 1883, using a metal plate coated with selenium and a thin layer of gold; the device became commercially useful in photographic light meters in

1365-525: A leading-edge system to track livestock. Forecasted domestic demand for the chip is as high as 1.5 million units for 2012 with an expected minimum growth rate of 10 percent a year over the next decade. The chip contains all vehicle data, including chassis and national registration numbers, taxes and fines not paid, etc. The chip is embedded in an electronic tag. It ensures the traceability and safety of blood products. The Design House worked on projects funded by FINEP. Semiconductor A semiconductor

1470-450: A low electric field. The crux of this device, invented by NKF in Delft in 1964, is that the bore of the elastic body is narrower than the diameter of the cable. In this way the (blue) interface between cable and stress-cone is brought under mechanical pressure so that no cavities or air pockets can be formed between cable and cone. Electric breakdown in this region is prevented in this way. This construction can further be surrounded by

1575-445: A low-pressure chamber to create plasma . A common etch gas is chlorofluorocarbon , or more commonly known Freon . A high radio-frequency voltage between the cathode and anode is what creates the plasma in the chamber. The silicon wafer is located on the cathode, which causes it to be hit by the positively charged ions that are released from the plasma. The result is silicon that is etched anisotropically . The last process

1680-401: A manhole or building vault. There can also be workmanship concerns with using a torch as the tubes must be fully recovered without scorching and any mastics used must flow into the voids and eliminate any air. Sufficient time and heat must be given. There are also a high number of components that must be placed in the correct order and position relative to the center of the joint. Cold shrink is

1785-407: A metallic shield. This is in contrast to an overhead line , which may include insulation but not fully rated for operating voltage (EG: tree wire). High-voltage cables of differing types have a variety of applications in instruments, ignition systems, and alternating current (AC) and direct current (DC) power transmission. In all applications, the insulation of the cable must not deteriorate due to

1890-626: A non-equilibrium situation. This introduces electrons and holes to the system, which interact via a process called ambipolar diffusion . Whenever thermal equilibrium is disturbed in a semiconducting material, the number of holes and electrons changes. Such disruptions can occur as a result of a temperature difference or photons , which can enter the system and create electrons and holes. The processes that create or annihilate electrons and holes are called generation and recombination, respectively. In certain semiconductors, excited electrons can relax by emitting light instead of producing heat. Controlling

1995-519: A pair is completed. Such carrier traps are sometimes purposely added to reduce the time needed to reach the steady-state. The conductivity of semiconductors may easily be modified by introducing impurities into their crystal lattice . The process of adding controlled impurities to a semiconductor is known as doping . The amount of impurity, or dopant, added to an intrinsic (pure) semiconductor varies its level of conductivity. Doped semiconductors are referred to as extrinsic . By adding impurity to

2100-471: A rigid pipe usually made of steel. With pipe-type cables, the pipes are constructed first, and then at a later date, the cable is pulled through. The cable may feature skid wires to prevent damage during the pulling process. The cross-sectional volume of oil in a pipe-type cable is significantly higher than in an oil-filled cable. These pipe-type cables are oil-filled at nominal low, medium, and high pressures. Higher voltages require higher oil pressures to prevent

2205-474: A sectored style design to reduce skin effect losses. Utility power cables are often designed to run at up to 75C, 90C, and 105C conductor temperatures. This temperature is limited by the construction standard and jacket selection. The conductor shield is always permanently bonded to the EPR or XLPE cable insulation in the solid dielectric cable. The semi-conductive insulation shield can be bonded or removable depending on

SECTION 20

#1732869187627

2310-437: A short period of popularity prior to 1960 in the low and medium voltage markets but was not widely used by most utilities. Existing PILC feeders are often considered to be near the end of life by most utilities and subject to replacement programs. Vulcanized rubber was patented by Charles Goodyear in 1844, but it was not applied to cable insulation until the 1880s when it was used for lighting circuits. Rubber-insulated cable

2415-501: A silicon atom in the crystal, a vacant state (an electron "hole") is created, which can move around the lattice and function as a charge carrier. Group V elements have five valence electrons, which allows them to act as a donor; substitution of these atoms for silicon creates an extra free electron. Therefore, a silicon crystal doped with boron creates a p-type semiconductor whereas one doped with phosphorus results in an n-type material. During manufacture , dopants can be diffused into

2520-461: A terminal or bi-manchet cuff is skilled work. The technical steps of removing the outer semiconducting layer at the end of the cables, placing the field-controlling bodies, connecting the conductors, etc., require skill, cleanliness, and precision. Hand taped joints are the old-school method of splicing and terminating cable. The construction of these joints involves taking several types of tape and manually building up appropriate stress relief. Some of

2625-773: A theory of solid-state physics , which developed greatly in the first half of the 20th century. In 1878 Edwin Herbert Hall demonstrated the deflection of flowing charge carriers by an applied magnetic field, the Hall effect . The discovery of the electron by J.J. Thomson in 1897 prompted theories of electron-based conduction in solids. Karl Baedeker , by observing a Hall effect with the reverse sign to that in metals, theorized that copper iodide had positive charge carriers. Johan Koenigsberger  [ de ] classified solid materials like metals, insulators, and "variable conductors" in 1914 although his student Josef Weiss already introduced

2730-472: A vacuum, though with a different effective mass . Because the electrons behave like an ideal gas, one may also think about conduction in very simplistic terms such as the Drude model , and introduce concepts such as electron mobility . For partial filling at the top of the valence band, it is helpful to introduce the concept of an electron hole . Although the electrons in the valence band are always moving around,

2835-567: A variety of proportions. These compounds share with better-known semiconductors the properties of intermediate conductivity and a rapid variation of conductivity with temperature, as well as occasional negative resistance . Such disordered materials lack the rigid crystalline structure of conventional semiconductors such as silicon. They are generally used in thin film structures, which do not require material of higher electronic quality, being relatively insensitive to impurities and radiation damage. Almost all of today's electronic technology involves

2940-450: Is PILC or paper insulation lead-covered cable. Some utilities still install this for distribution circuits as new construction or replacement. Sebastian Ziani de Ferranti was the first to demonstrate in 1887 that carefully dried and prepared kraft paper could form satisfactory cable insulation at 11,000 volts. Previously paper-insulated cable had only been applied for low-voltage telegraph and telephone circuits. An extruded lead sheath over

3045-415: Is a combination of processes that are used to prepare semiconducting materials for ICs. One process is called thermal oxidation , which forms silicon dioxide on the surface of the silicon . This is used as a gate insulator and field oxide . Other processes are called photomasks and photolithography . This process is what creates the patterns on the circuit in the integrated circuit. Ultraviolet light

3150-547: Is a critical element for fabricating most electronic circuits . Semiconductor devices can display a range of different useful properties, such as passing current more easily in one direction than the other, showing variable resistance, and having sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by doping and by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion . The term semiconductor

3255-467: Is a function of the temperature, as the probability of getting enough thermal energy to produce a pair increases with temperature, being approximately exp(− E G / kT ) , where k is the Boltzmann constant , T is the absolute temperature and E G is bandgap. The probability of meeting is increased by carrier traps – impurities or dislocations which can trap an electron or hole and hold it until

CEITEC - Misplaced Pages Continue

3360-453: Is a material that is between the conductor and insulator in ability to conduct electrical current. In many cases their conducting properties may be altered in useful ways by introducing impurities (" doping ") into the crystal structure . When two differently doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers , which include electrons , ions , and electron holes , at these junctions

3465-428: Is also used to describe materials used in high capacity, medium- to high-voltage cables as part of their insulation, and these materials are often plastic XLPE ( Cross-linked polyethylene ) with carbon black. The conductivity of silicon is increased by adding a small amount (of the order of 1 in 10 ) of pentavalent ( antimony , phosphorus , or arsenic ) or trivalent ( boron , gallium , indium ) atoms. This process

3570-404: Is called diffusion . This is the process that gives the semiconducting material its desired semiconducting properties. It is also known as doping . The process introduces an impure atom to the system, which creates the p–n junction . To get the impure atoms embedded in the silicon wafer, the wafer is first put in a 1,100 degree Celsius chamber. The atoms are injected in and eventually diffuse with

3675-776: Is inert, blocking the passage of other electrons via that state. The energies of these quantum states are critical since a state is partially filled only if its energy is near the Fermi level (see Fermi–Dirac statistics ). High conductivity in material comes from it having many partially filled states and much state delocalization. Metals are good electrical conductors and have many partially filled states with energies near their Fermi level. Insulators , by contrast, have few partially filled states, their Fermi levels sit within band gaps with few energy states to occupy. Importantly, an insulator can be made to conduct by increasing its temperature: heating provides energy to promote some electrons across

3780-418: Is known as doping, and the resulting semiconductors are known as doped or extrinsic semiconductors . Apart from doping, the conductivity of a semiconductor can be improved by increasing its temperature. This is contrary to the behavior of a metal, in which conductivity decreases with an increase in temperature. The modern understanding of the properties of a semiconductor relies on quantum physics to explain

3885-841: Is neither a very good insulator nor a very good conductor. However, one important feature of semiconductors (and some insulators, known as semi-insulators ) is that their conductivity can be increased and controlled by doping with impurities and gating with electric fields. Doping and gating move either the conduction or valence band much closer to the Fermi level and greatly increase the number of partially filled states. Some wider-bandgap semiconductor materials are sometimes referred to as semi-insulators . When undoped, these have electrical conductivity nearer to that of electrical insulators, however they can be doped (making them as useful as semiconductors). Semi-insulators find niche applications in micro-electronics, such as substrates for HEMT . An example of

3990-415: Is often polymeric. The function of the jacket is to provide mechanical protection as well as prevent moisture & chemical intrusion. Jackets can be semiconducting or non-conducting depending on soil conditions and desired grounding configuration. Semiconducting jackets can also be employed on cables to help with a jacket integrity test. Some types of jackets are LLDPE, HDPE, polypropylene, PVC (bottom end of

4095-404: Is reached by a process called recombination , which causes the migrating electrons from the n-type to come in contact with the migrating holes from the p-type. The result of this process is a narrow strip of immobile ions , which causes an electric field across the junction. A difference in electric potential on a semiconducting material would cause it to leave thermal equilibrium and create

4200-413: Is the basis of diodes , transistors , and most modern electronics . Some examples of semiconductors are silicon , germanium , gallium arsenide , and elements near the so-called " metalloid staircase " on the periodic table . After silicon, gallium arsenide is the second-most common semiconductor and is used in laser diodes , solar cells , microwave-frequency integrated circuits , and others. Silicon

4305-610: Is the more rapidly growing area of distribution splices and is thought to have the fewest workmanship issues with the quickest install times. X-ray cables are used in lengths of several meters to connect the HV source with an X-ray tube or any other HV device in scientific equipment. They transmit small currents, in the order of milliamperes at DC voltages of 30 to 200 kV, or sometimes higher. The cables are flexible, with rubber or other elastomer insulation, stranded conductors, and an outer sheath of braided copper wire. The construction has

CEITEC - Misplaced Pages Continue

4410-502: Is the partial discharge test. One needs to distinguish between cable testing and cable diagnosis . While cable testing methods result in a go/no go statement cable diagnosis methods allow judgment of the cable's current condition. With some tests, it is even possible to locate the position of the defect in the insulation before failure. In some cases, electrical treeing (water trees) can be detected by tan delta measurement . Interpretation of measurement results can in some cases yield

4515-635: Is to prevent air-filled cavities and suppress voltage stress between the metal conductors and the dielectric so that little electric discharges cannot arise and endanger the insulation material. The insulation shield is covered by a copper, aluminum, or lead "screen." The metallic shield or sheath serves as an earthed layer and will drain leakage currents. The shield's function is not to conduct faults but that functionality can be designed if desired. Some designs that could be used are copper tape, concentric copper wires, longitudinally corrugated shields, copper flat straps, or extruded lead sheath. The cable jacket

4620-500: Is typically very dilute, and so (unlike in metals) it is possible to think of the electrons in the conduction band of a semiconductor as a sort of classical ideal gas , where the electrons fly around freely without being subject to the Pauli exclusion principle . In most semiconductors, the conduction bands have a parabolic dispersion relation , and so these electrons respond to forces (electric field, magnetic field, etc.) much as they would in

4725-402: Is used along with a photoresist layer to create a chemical change that generates the patterns for the circuit. The etching is the next process that is required. The part of the silicon that was not covered by the photoresist layer from the previous step can now be etched. The main process typically used today is called plasma etching . Plasma etching usually involves an etch gas pumped in

4830-551: Is used at all voltage levels from the 600V class and up. Sometimes EAM insulation is marketed, however, market penetration remains fairly low. Solid, extruded insulation cables such as EPR and XLPE account for the majority of distribution and transmission cables produced today. However, the relative unreliability of early XLPE resulted in a slow adoption at transmission voltages. Cables of 330, 400, and 500 kV are commonly constructed using XLPE today, but this has occurred only in recent decades. An increasingly uncommon insulation type

4935-690: Is very difficult. Pre-molded joints are injection molded bodies created in two or more stages. Due to automation, the faraday cage will have a precise geometry and placement not achievable in taped joints. Pre-molded joints come in many different body sizes that much be matched up to the cable Semicon's outside diameter. A tight joint interface is required to ensure waterproofing. These joints are often pushed on and can cause soft tissue injuries among craftsmen. Heat shrink joints consist of many different heat shrink tubes: insulating and conducting. These kits are less labor-intensive than taping but more than pre-molded. There can be concerns about having an open flame in

5040-527: The Annalen der Physik und Chemie in 1835; Rosenschöld's findings were ignored. Simon Sze stated that Braun's research was the earliest systematic study of semiconductor devices. Also in 1874, Arthur Schuster found that a copper oxide layer on wires had rectification properties that ceased when the wires are cleaned. William Grylls Adams and Richard Evans Day observed the photovoltaic effect in selenium in 1876. A unified explanation of these phenomena required

5145-429: The Pauli exclusion principle ). These states are associated with the electronic band structure of the material. Electrical conductivity arises due to the presence of electrons in states that are delocalized (extending through the material), however in order to transport electrons a state must be partially filled , containing an electron only part of the time. If the state is always occupied with an electron, then it

5250-450: The Siege of Leningrad after successful completion. In 1926, Julius Edgar Lilienfeld patented a device resembling a field-effect transistor , but it was not practical. R. Hilsch  [ de ] and R. W. Pohl  [ de ] in 1938 demonstrated a solid-state amplifier using a structure resembling the control grid of a vacuum tube; although the device displayed power gain, it had

5355-445: The band gap , be accompanied by the emission of thermal energy (in the form of phonons ) or radiation (in the form of photons ). In some states, the generation and recombination of electron–hole pairs are in equipoise. The number of electron-hole pairs in the steady state at a given temperature is determined by quantum statistical mechanics . The precise quantum mechanical mechanisms of generation and recombination are governed by

SECTION 50

#1732869187627

5460-470: The conservation of energy and conservation of momentum . As the probability that electrons and holes meet together is proportional to the product of their numbers, the product is in the steady-state nearly constant at a given temperature, providing that there is no significant electric field (which might "flush" carriers of both types, or move them from neighbor regions containing more of them to meet together) or externally driven pair generation. The product

5565-471: The electric fields at the ends. Without such a construction the electric field will concentrate at the end of the earth-conductor as shown in figure 8. Equipotential lines are shown here, which can be compared with the contour lines on a map of a mountainous region: the nearer these lines are to each other, the steeper the slope and the greater the danger, in this case, the danger of an electrical breakdown . The equipotential lines can also be compared with

5670-404: The isobars on a weather map: The denser the lines, the more wind and the greater the danger of damage. In order to control the equipotential lines (that is to control the electric field) a device is used that is called a stress cone , see figure 9. The crux of stress relief is to flare the shield end along a logarithmic curve. Before 1960, the stress cones were handmade using tape—after the cable

5775-461: The 1930s. Point-contact microwave detector rectifiers made of lead sulfide were used by Jagadish Chandra Bose in 1904; the cat's-whisker detector using natural galena or other materials became a common device in the development of radio . However, it was somewhat unpredictable in operation and required manual adjustment for best performance. In 1906, H.J. Round observed light emission when electric current passed through silicon carbide crystals,

5880-410: The 1980s and 1990s as urban utilities started to install more EPR and XLPE insulated cables. The factors for the decreased use of PILC are the high level of craftsmanship needed to splice lead, longer splicing times, reduced availability of the product domestically, and pressure to stop using lead for environmental and safety reasons. It should also be noted that rubber insulated lead-covered cable enjoyed

5985-661: The Chip for animal identification design at its facilities because X-Fab CMOS 0.6 micron technology is the same that will soon be available in CEITEC’s own factory that will be the first of its kind in Latin America to manufacture RF analog/digital products. It can produce up to 100 million chips per year using 6-inch wafers. CEITEC’s Chip for animal identification is an advanced LF-RFID device designed for use in Brazil’s cattle industry as part of

6090-416: The band gap, inducing partially filled states in both the band of states beneath the band gap ( valence band ) and the band of states above the band gap ( conduction band ). An (intrinsic) semiconductor has a band gap that is smaller than that of an insulator and at room temperature, significant numbers of electrons can be excited to cross the band gap. A pure semiconductor, however, is not very useful, as it

6195-474: The cable will fail due to electrical stress within minutes. This technique was patented by Martin Hochstadter in 1916; the shield is sometimes called a Hochstadter shield and shielded cable used to be called H-Type Cable. Depending on the grounding scheme, the shields of a cable can be connected to the ground at one end or both ends of the cable. Splices in the middle of the cable can be also grounded depending on

6300-406: The concentration and regions of p- and n-type dopants. A single semiconductor device crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behavior. Using a hot-point probe , one can determine quickly whether a semiconductor sample is p- or n-type. A few of the properties of semiconductor materials were observed throughout

6405-489: The concept of band gaps had been developed. Walter H. Schottky and Nevill Francis Mott developed models of the potential barrier and of the characteristics of a metal–semiconductor junction . By 1938, Boris Davydov had developed a theory of the copper-oxide rectifier, identifying the effect of the p–n junction and the importance of minority carriers and surface states. Agreement between theoretical predictions (based on developing quantum mechanics) and experimental results

SECTION 60

#1732869187627

6510-403: The conductor of that cable and blue the insulation of the cable. The black parts in this picture are semiconducting rubber parts. The outer one is at earth potential and spreads the electric field in a similar way as in a cable terminal. The inner one is at high voltage and shields the connector of the conductors from the electric field. The field itself is diverted as shown in figure 11, where

6615-451: The desires of the purchaser. For voltages 69KV and up the insulation shield is generally bonded. A strippable insulation shield is purchased to reduce splicing time and skill. It can be argued that strippable Semicon can lead to fewer workmanship issues at medium voltage. With paper insulated cables the semiconducting layers consist of carbon-bearing or metalized tapes applied over the conductor and paper insulation. The function of these layers

6720-453: The electrical properties of materials. The properties of the time-temperature coefficient of resistance, rectification, and light-sensitivity were observed starting in the early 19th century. Thomas Johann Seebeck was the first to notice that semiconductors exhibit special feature such that experiment concerning an Seebeck effect emerged with much stronger result when applying semiconductors, in 1821. In 1833, Michael Faraday reported that

6825-530: The electrons in the conduction band). When ionizing radiation strikes a semiconductor, it may excite an electron out of its energy level and consequently leave a hole. This process is known as electron-hole pair generation . Electron-hole pairs are constantly generated from thermal energy as well, in the absence of any external energy source. Electron-hole pairs are also apt to recombine. Conservation of energy demands that these recombination events, in which an electron loses an amount of energy larger than

6930-479: The equipotential lines are smoothly directed from the inside of the cable to the outer part of the bi-manchet (and vice versa at the other side of the device). The crux of the matter is here, like in the cable terminal, that the inner bore of this bi-manchet is chosen smaller than the diameter over the cable insulation. In this way a permanent pressure is created between the bi-manchet and the cable surface, and cavities or electrical weak points are avoided. Installing

7035-514: The fast response of crystal detectors. Considerable research and development of silicon materials occurred during the war to develop detectors of consistent quality. Detector and power rectifiers could not amplify a signal. Many efforts were made to develop a solid-state amplifier and were successful in developing a device called the point contact transistor which could amplify 20 dB or more. In 1922, Oleg Losev developed two-terminal, negative resistance amplifiers for radio, but he died in

7140-437: The formation of voids that would allow partial discharges within the cable insulation. Pipe-type cables will typically have a cathodic protection system driven off voltage where an oil-filled cable circuit would not. Pipe-type cable systems are often protected from forming holidays through an asphaltic coating. There are still many of these pipe-type circuits in operation today. However, they have fallen out of favor due to

7245-412: The high front-end cost and massive O+M budget needed to maintain the fleet of pumping plants. High voltage is defined as any voltage over 1000 volts. Those of 2 to 33 kV are usually called medium voltage cables, those over 50 kV high voltage cables. Modern HV cables have a simple design consisting of a few parts: the conductor, the conductor shield, the insulation, the insulation shield,

7350-669: The high-voltage stress, ozone produced by electric discharges in air, or tracking. The cable system must prevent contact of the high-voltage conductor with other objects or persons, and must contain and control leakage current. Cable joints and terminals must be designed to control the high-voltage stress to prevent the breakdown of the insulation. The cut lengths of high-voltage cables may vary from several feet to thousands of feet, with relatively short cables used in apparatus and longer cables run within buildings or as buried cables in an industrial plant or for power distribution. The longest cut lengths of cable will often be submarine cables under

7455-554: The insulation remains imperative. The semiconducting material can be plastic XLPE ( Cross-linked polyethylene ) with carbon black. Many HVDC cables are used for DC submarine connections , because at distances over approximately 100 km AC can no longer be used. As of 2021 the longest submarine cable is the North Sea Link cable between Norway and the UK which is 720 km (450 mi) long. Terminals of high-voltage cables must manage

7560-428: The length of the circuit and if a semiconducting jacket is employed on direct buried circuits. Since 1960 solid dielectric extruded cables have taken dominance in the distribution market. These medium voltage cables are generally insulated with EPR or XLPE polymeric insulation. EPR insulation is common on cables from 4 to 34kV. EPR is not commonly used over 35KV due to losses, however, it can be found in 69kV cables. XLPE

7665-421: The liquidation of Ceitec. On 2 January 2023, presidente Lula da Silva suspended the process of liquidation. On January 2, 2023 Luciana Santos entered the office of Minister of Science, Technology and Innovations. Among other things, she promised to review the liquidation. Chip for animal identification is CEITEC S.A.’s first commercial product and is the first chip designed in Brazil by Brazilian engineers in

7770-442: The market), LSZH, etc. During the development of high voltage insulation, which has taken about half a century, two characteristics proved to be paramount. First, the introduction of the semiconducting layers. These layers must be absolutely smooth, without even protrusions as small as a few μm . Further, the fusion between the insulation and these layers must be absolute; any fission, air-pocket or other defect — again, even of

7875-543: The material's majority carrier . The opposite carrier is called the minority carrier , which exists due to thermal excitation at a much lower concentration compared to the majority carrier. For example, the pure semiconductor silicon has four valence electrons that bond each silicon atom to its neighbors. In silicon, the most common dopants are group III and group V elements. Group III elements all contain three valence electrons, causing them to function as acceptors when used to dope silicon. When an acceptor atom replaces

7980-499: The metallic shield, and the jacket. Other layers can include water blocking tapes, ripcords, and armor wires. Copper or aluminum wires transports the current, see (1) in figure 1. ( For a detailed discussion on copper cables, see main article: Copper conductor . ) The insulation, insulation shield, and conductor shield are generally polymer-based with a few rare exceptions. Single conductor designs under 2000 KCM are generally concentric. The individual strands are often deformed during

8085-435: The mid-19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector , a primitive semiconductor diode used in early radio receivers. Developments in quantum physics led in turn to the invention of the transistor in 1947 and the integrated circuit in 1958. Semiconductors in their natural state are poor conductors because

8190-505: The movement of charge carriers in a crystal lattice . Doping greatly increases the number of charge carriers within the crystal. When a semiconductor is doped by Group V elements, they will behave like donors creating free electrons , known as " n-type " doping. When a semiconductor is doped by Group III elements, they will behave like acceptors creating free holes, known as " p-type " doping. The semiconductor materials used in electronic devices are doped under precise conditions to control

8295-417: The newest family of joints. The idea is a polymer tube is formed at the correct diameter for the cable. It is then expanded over a form and placed onto a hold-out tube at the factory. Then ready for installation the joint is very easily slipped over the cable end. After the connector is installed the splicer simply needs to center the joint body and then release the holdout. The tube will automatically recover to

8400-462: The number and size of foreign particles are guaranteed. Packing the raw material and unloading it within a cleanroom environment in the cable-making machines is required. The development of extruders for plastics extrusion and cross-linking has resulted in cable-making installations for making defect-free and pure insulations. The final quality control test is an elevated voltage 50 or 60 Hz partial discharge test with very high sensitivity (in

8505-480: The ocean for power transmission. Like other power cables , high-voltage cables have the structural elements of one or more conductors, an insulation system, and a protective jacket. High-voltage cables differ from lower-voltage cables in that they have additional internal layers in the insulation system to control the electric field around the conductor. These additional layers are required at 2,000 volts and above between conductors. Without these semi-conducting layers,

8610-410: The original size. The only complication is cold shrink has a shelf life of approximately 2–3 years. After that time period, the rubber will form memory and not recover down to the intended size. This can lead to joint failure if not installed before the recommended date. From a utility perspective, this makes it difficult to keep track of stock or retain emergency spares for critical customers. Cold shrink

8715-449: The other. A slice cut from the specimen at the p–n boundary developed a voltage when exposed to light. The first working transistor was a point-contact transistor invented by John Bardeen , Walter Houser Brattain , and William Shockley at Bell Labs in 1947. Shockley had earlier theorized a field-effect amplifier made from germanium and silicon, but he failed to build such a working device, before eventually using germanium to invent

8820-466: The paper cable was required to ensure that the paper remained moisture-free. Mass-impregnated paper-insulated medium voltage cables were commercially practical by 1895. During World War II several varieties of synthetic rubber and polyethylene insulation were applied to cables. Modern high-voltage cables use polymers, especially polyethylene, including cross-linked polyethylene (XLPE) for insulation. The demise of PILC could be considered to be in

8925-508: The point-contact transistor. In France, during the war, Herbert Mataré had observed amplification between adjacent point contacts on a germanium base. After the war, Mataré's group announced their " Transistron " amplifier only shortly after Bell Labs announced the " transistor ". In 1954, physical chemist Morris Tanenbaum fabricated the first silicon junction transistor at Bell Labs . However, early junction transistors were relatively bulky devices that were difficult to manufacture on

9030-399: The possibility to distinguish between new, strongly water treed cable. Unfortunately, there are many other issues that can erroneously present themselves as high tangent delta, and the vast majority of solid dielectric defects can not be detected with this method. Damage to the insulation and electrical treeing may be detected and located by partial discharge measurement . Data collected during

9135-524: The principle behind the light-emitting diode . Oleg Losev observed similar light emission in 1922, but at the time the effect had no practical use. Power rectifiers, using copper oxide and selenium, were developed in the 1920s and became commercially important as an alternative to vacuum tube rectifiers. The first semiconductor devices used galena , including German physicist Ferdinand Braun's crystal detector in 1874 and Indian physicist Jagadish Chandra Bose's radio crystal detector in 1901. In

9240-574: The pure semiconductors, the electrical conductivity may be varied by factors of thousands or millions. A 1 cm specimen of a metal or semiconductor has the order of 10 atoms. In a metal, every atom donates at least one free electron for conduction, thus 1 cm of metal contains on the order of 10 free electrons, whereas a 1 cm sample of pure germanium at 20   °C contains about 4.2 × 10 atoms, but only 2.5 × 10 free electrons and 2.5 × 10 holes. The addition of 0.001% of arsenic (an impurity) donates an extra 10 free electrons in

9345-449: The range of 5 to 10 picocoulombs) This test is performed on every reel of cable before it is shipped. A high-voltage cable for high-voltage direct current (HVDC) transmission has the same construction as the AC cable shown in figure 1. The physics and the test requirements are different. In this case the smoothness of the semiconducting layers (2) and (4) is of utmost importance. Cleanliness of

9450-629: The resistance of specimens of silver sulfide decreases when they are heated. This is contrary to the behavior of metallic substances such as copper. In 1839, Alexandre Edmond Becquerel reported observation of a voltage between a solid and a liquid electrolyte, when struck by light, the photovoltaic effect . In 1873, Willoughby Smith observed that selenium resistors exhibit decreasing resistance when light falls on them. In 1874, Karl Ferdinand Braun observed conduction and rectification in metallic sulfides , although this effect had been discovered earlier by Peter Munck af Rosenschöld ( sv ) writing for

9555-400: The same elements as other HV power cables. There are different causes for faulty cable insulation when considering solid dielectric or paper insulation. Hence, there are various test and measurement methods to prove fully functional cables or to detect faulty ones. While paper cables are primarily tested with DC insulation resistance tests the most common test for solid dielectric cable systems

9660-534: The same volume and the electrical conductivity is increased by a factor of 10,000. The materials chosen as suitable dopants depend on the atomic properties of both the dopant and the material to be doped. In general, dopants that produce the desired controlled changes are classified as either electron acceptors or donors . Semiconductors doped with donor impurities are called n-type , while those doped with acceptor impurities are known as p-type . The n and p type designations indicate which charge carrier acts as

9765-472: The same way as the electron. Combined with the negative effective mass of the electrons at the top of the valence band, we arrive at a picture of a positively charged particle that responds to electric and magnetic fields just as a normal positively charged particle would do in a vacuum, again with some positive effective mass. This particle is called a hole, and the collection of holes in the valence band can again be understood in simple classical terms (as with

9870-591: The scale at which the materials are used. A high degree of crystalline perfection is also required, since faults in the crystal structure (such as dislocations , twins , and stacking faults ) interfere with the semiconducting properties of the material. Crystalline faults are a major cause of defective semiconductor devices. The larger the crystal, the more difficult it is to achieve the necessary perfection. Current mass production processes use crystal ingots between 100 and 300 mm (3.9 and 11.8 in) in diameter, grown as cylinders and sliced into wafers . There

9975-425: The semiconductor body by contact with gaseous compounds of the desired element, or ion implantation can be used to accurately position the doped regions. Some materials, when rapidly cooled to a glassy amorphous state, have semiconducting properties. These include B, Si , Ge, Se, and Te, and there are multiple theories to explain them. The history of the understanding of semiconductors begins with experiments on

10080-1007: The semiconductor composition and electrical current allows for the manipulation of the emitted light's properties. These semiconductors are used in the construction of light-emitting diodes and fluorescent quantum dots . Semiconductors with high thermal conductivity can be used for heat dissipation and improving thermal management of electronics. They play a crucial role in electric vehicles , high-brightness LEDs and power modules , among other applications. Semiconductors have large thermoelectric power factors making them useful in thermoelectric generators , as well as high thermoelectric figures of merit making them useful in thermoelectric coolers . A large number of elements and compounds have semiconducting properties, including: The most common semiconducting materials are crystalline solids, but amorphous and liquid semiconductors are also known. These include hydrogenated amorphous silicon and mixtures of arsenic , selenium , and tellurium in

10185-458: The silicon. After the process is completed and the silicon has reached room temperature, the doping process is done and the semiconducting wafer is almost prepared. Semiconductors are defined by their unique electric conductive behavior, somewhere between that of a conductor and an insulator. The differences between these materials can be understood in terms of the quantum states for electrons, each of which may contain zero or one electron (by

10290-400: The stranding process to provide a smoother overall circumference. These are known as compact and compressed conductors. Compact offers a 10% reduction in conductor outer diameter while the compressed version only offers a 3% decrease. The selection of a compressed or compact conductor will often require a different connector during splicing. 2000 KCM and larger transmission cables often include

10395-403: The tapes involved could be rubber tapes, semiconducting tapes, friction tapes, varnished cambric tapes, etc. This splicing method is incredibly labor and time-intensive. It requires measuring the diameter and length of the layers being built up. Often the tapes must be half-lapped and pulled tight to prevent the formation of windows or voids in the resulting splice. Waterproofing hand taped splicing

10500-407: The term Halbleiter (a semiconductor in modern meaning) in his Ph.D. thesis in 1910. Felix Bloch published a theory of the movement of electrons through atomic lattices in 1928. In 1930, B. Gudden  [ de ] stated that conductivity in semiconductors was due to minor concentrations of impurities. By 1931, the band theory of conduction had been established by Alan Herries Wilson and

10605-406: The use of semiconductors, with the most important aspect being the integrated circuit (IC), which are found in desktops , laptops , scanners, cell-phones , and other electronic devices. Semiconductors for ICs are mass-produced. To create an ideal semiconducting material, chemical purity is paramount. Any small imperfection can have a drastic effect on how the semiconducting material behaves due to

10710-467: The years preceding World War II, infrared detection and communications devices prompted research into lead-sulfide and lead-selenide materials. These devices were used for detecting ships and aircraft, for infrared rangefinders, and for voice communication systems. The point-contact crystal detector became vital for microwave radio systems since available vacuum tube devices could not serve as detectors above about 4000 MHz; advanced radar systems relied on

10815-409: Was installed. These were protected by potheads , so named because a potting compound/dielectric was poured around the tape inside a metal/ porcelain body insulator. About 1960, preformed terminations were developed consisting of a rubber or elastomer body that is stretched over the cable end. On this rubber-like body R a shield electrode is applied that spreads the equipotential lines to guarantee

10920-637: Was sometimes poor. This was later explained by John Bardeen as due to the extreme "structure sensitive" behavior of semiconductors, whose properties change dramatically based on tiny amounts of impurities. Commercially pure materials of the 1920s containing varying proportions of trace contaminants produced differing experimental results. This spurred the development of improved material refining techniques, culminating in modern semiconductor refineries producing materials with parts-per-trillion purity. Devices using semiconductors were at first constructed based on empirical knowledge before semiconductor theory provided

11025-604: Was used for 11,000 volt circuits in 1897 installed for the Niagara Falls Power Generation project. Oil-filled, gas-filled, and pipe-type cables have been largely considered obsolete since the 1960s. Such cables are designed to have significant oil flow through the cable. Standard PILC cables are impregnated with oil but the oil is not designed to flow or cool the cable. Oil-filled cables are typically lead-insulated and can be purchased on reels. Pipe-type cables differ from oil-filled cables in that they are installed in

#626373