Category Archives: Electrical

Uninterruptible Power Supply (UPS) – Technological Overview

(UPS) Uninterruptible Power Supply or flywheel/battery backup is that electrical apparatus which provide emergency powers to loads when failure typically of input power sources or mains power is there. UPS differs from emergency or auxiliary power systems or standby generators. In this there is provision of near instantaneous protections from interruptions of input powers. This is by supplying stored energy in flywheels, batteries or super capacitors. On battery runtimes of most UPS’s are short relatively for few minutes only. But there is sufficient starting of standby power sources or proper shutting down of equipment protected. Typically UPS has been used for protecting hardware like data centres, telecommunication equipment, computers and different electrical equipment. In this there is power disruption unexpected which causes data loss, injuries, fatalities, and business disruption serious. UPS units range in sizes from designed units for protecting single computers with no video monitors, being 200 volt-ampere rating. There are large units which powers entire buildings or data centres. World’s most large UPS is 46- megawatt (BESS) Battery Electric Storage System in Alaska, Fairbanks, in turn power entire cities and nearby communities rurally since times of outages.

Technologies: Standby or Offline: This UPS (SPS) only offers very basic features. It provides battery backup and surge protection. Equipment protected is connected normally directly to utility power incoming. The incoming voltage fall below or rise above level predetermined. SPS turn on DC-AC internal inverter circuitry. It is powered from storage internal battery. UPS switches mechanically equipment connected to its DC-AC output inverter. A switchover time is 25 milliseconds long whilst depending on time amount. It takes UPS standby for detecting utility lost voltage. UPS is designed for powering some equipment like personal computer, with no objectionable brownout or dip for devices. Line-interactive: This UPS is same in operation to UPS standby. This is with addition of multi-tap auto transformer variable-voltage. It is special transformer type which subtracts or adds wire coils powered. It decreases or increases output voltage and magnetic field f transformer. It is called also Buck-boost Transformer. UPS type has ability of tolerating under voltage continuous brownout and surges over voltage. There is no consumption of reserve limited battery power. It is instead compensated by automatic selection of various auto transformers’ power taps. Whilst depending on designs, change of auto transformer taps causes too much brief power output disruption. It causes UPSs being equipped with alarm power-loss for “chirping” for moments. Double-conversion/online: In this UPS, batteries are connected always to inverter such that no switches of power transfer are needed. When there is occurrence of power loss, rectifier drops simply out of circuit. Batteries keep powers unchanged and steady. When there is restoration of power, rectifiers resume carrying most loads. Batteries begin charging though currents charging are limited. This prevents high power rectification from battery overheating and electrolyte boiling off. Important benefit of online UPS is abilities of providing “electrical firewall” in between electronic sensitive equipment and utility power incoming. Application: N+1: In business large environments where reliabilities are of importance too much, single UPS hugely also could be single failure points which disrupts lots of different systems. For providing great reliabilities, lots of small UPS batteries and modules are together integrated for providing redundant power protections being equivalent to 1 too much large UPS. “N+1” meaning is that is loads are supplied by N modules, installation contains N+1 module. By this process, 1 module failure shall not have impact on operation of system. Numerous redundancies: Computer servers many offer power supplies redundant options. In event of 1 power supply failure, 1 or more varied different power supplies have abilities of powering loads.

Vector Control of Induction Motor: Technical Overview and Application

Vector Control of Induction Motor is called also (FOC) field-oriented control. It is (VFD) variable frequency drive controlling way. In this stator current of 3 phase AC electric motor is identified as 2 components orthogonally being visualized with vectors. 1 component defines motor’s magnetic flux. Other component defines torque. Control systems of drive calculate from torque and flux reference. This is provided by speed controls of drives which correspond to references of current components. (PI) Proportional-integral controllers typically have been used for keeping current measured components at reference values. Pulse width modulations of variable frequency drives thereby defines transistor switching as per stator reference voltage which are output of PI current controller. FOC has been used for controlling induction motors and AC synchronous motors. It was developed originally for high performance motor applications. It is needed for smooth operation over full speeded ranges, generating full torques at zero speeds and having high dynamic performances. This includes deceleration and fast acceleration. It is, however, increasingly becoming attractive for low performance applications. It is due to FOC’s power consumption, cost and motor size superiority reduction. It has been expected that together with increased computational microprocessor powers it shall nearly eventually universally displace scalar single variable volts-per-hertz (V/f) controls.

Overview technically: Whilst analysis of AC driving controls is technically involved, such analysis starts invariably with modelling of drive motor circuits being involved through lines of signal flow graphs and equation accompaniment. In vector controls of Induction Motor the motor have been controlled in operating conditions like separate excited DC motors. AC motors behave like DC motors where armature flux linkage and field flux linkage are created by respective fields. Armature currents or torque components are aligned orthogonally. When torque has been controlled, field flux linkages are not affected. This enables dynamic torque responses. Vector controls generate accordingly 3 phase PWM motor output voltages being derived from complex voltage vectors for controlling complex current vectors. This is derived from induction motor’s 3 phase stator current inputs by means of rotations or projections forth and back. This is in between 3 phase time and speed dependent systems. There are vectors rotating reference frames 2 coordinate time invariant system. Complex stator space current vectors of this kind are defined in (d, q) coordinate systems with component orthogonally through q (quadrature) and d (direct) axes. Field flux linkages current components are aligned along d axis. Torque current components are aligned along q axis. Induction motor’s (d, q) coordinate systems are superimposed to instantaneous (a, b, c) 3 phase sinusoidal system of motor. Components of (d, q) system current vectors in turn allow control conventionally like PI control or proportional and integral motor, as with DC motors. There are 2 vector controlling ways: Direct or Feedback vector control (DFOC) and Indirect or Feedforward vector control (IFOC). More commonly being used is IFOC, since in closed loop modes; drives have very easy operation throughout speed ranging from 0 speeds to high speed field weakening. In DFOC, angle feedback and flux magnitude signals are calculated directly by using so called current or voltage models. In IFOC angle feedforward flux magnitude and flux space signals 1st measure stator rotor speeds and currents. It is then deriving of flux spaces angling proper by summing rotor angles. This corresponds to rotor speeds and reference value calculated of slip angles which correspond to slip frequencies.

Application: Phase stator currents are measured and converted to complex space vectors in (a, b, c) coordinate systems. Current vectors are converted to (alpha, beta) coordinate systems.

Flexible Photovoltaic Technology: Its features, benefits and Applications

Flexible Photovoltaic Technology is technology of research levels. It was example of one that had been created at Massachusetts Institute of Technology. In this solar cells were manufactured by deposition of photovoltaic materials on substrates that are flexible like ordinary paper. There is also usage of chemical vapour deposition technologies. Manufacturing technologies of solar cell on paper had been developed by researchers group from National Science Foundation and Eni-MIT Alliance Solar Frontiers Program.

Features: Photovoltaic organic circuit materials have been deposited in 5 layers on substrates of ordinary paper in vacuum chambers. This is done by conformal coating of conductive electrode polymer with chemical oxidative vapours. Process is called chemical vapour deposition. Solar panels of this kind have capabilities of voltage production which exceeds 50 V. This in turn power appliance normally at lighting conditions. Solar cells are shown also being flexible. Conductive solar cells grids are same as inkjet photo printouts with rectangles patterned. When leads have been attached to substrates electrically, it has to be shown to electrical power appliances. “Printing” costs (as described by MIT) is claimed for being same as photo inkjet printing. The technology makes use of vapour deposition temperatures being less than 120 degrees. This becomes easy for manufacturing on ordinary papers. Panel’s current efficiency is nearly 1%. Researchers hope for improvement in near futures. Testing: Circuits were tested also by deposition of photovoltaic materials on (PET) polyethylene terephthalate substrates. PET sheets were unfolded and folded 1000 times. No over ting performance deterioration had been observed. There are photovoltaic materials common being deposited on deteriorated PET with only 1 fold. Solar cell was passed also by means of laser printing for demonstrating performance continued after exposures to temperatures somewhat high. It still retains procedural characteristics.

Benefits: In solar panels conventionally, panel’s supporting structures like brackets and glass are 2 times more costly as materials of photovoltaic being manufactured on them. Paper in turn costs 1 thousandth of glass approximately. Solar cells use printing process. This is much cheap than solar panels conventionally. Different methods also which involves coating papers along with material includes 1st paper coating with smooth materials for counter acting molecular scale’s paper rough. But in this process, photovoltaic materials are directly coated onto paper untreated.

Applications: In case solar cells achieve in turn sufficient maturity technologically, they are used as window shades and wall papers for electricity production from lighting room. They also can be manufactured on the clothing. This can be used for charging portable devices electronically such as media players and mobile phones. Solar flexible modules are used on roofs curved or on those roofs where there is no sense of installing rack mounting systems.

Disadvantages: For lasting more than 20 years outdoors being having elements exposure, solar cells are finished with front sheets of thermoplastic olefin or UV resistant fluoropolymer instead of glass being used in solar cells conventional. This is less costly comparatively. Solar cells should be sealed such that oxygen and water do not enter and destroy cells by means of oxidative degradation. Photovoltaic solar cell: Solar panels are imagined when one thinks of solar power (polycrystalline and monocrystalline). Flexible photovoltaic technology is composed not of highly silicon refined crystals. But instead it is 1 continuous material. 4 types of (TFPV) thin-film solar photovoltaic being classified by photovoltaic materials are used. TFPV principle is same as crystalline PV. Light strikes material. It excites electrons. Then flow by means of p-n junction permutation, thereby generating electricity’s that is utilized and captured.

There are amorphous silicon (aSi) solar photovoltaic cells: This was developed in seventies. It was made from silicon’s non-crystalline form.

66 kV Switchyards: Scope of Project and Objectives

Scope of Project: Existing 7 MVA replacement (5 MVA and 2 MVA 66 kV: 2.4 kV transformers) switch-yards with novice 66 kV switchyards in turn consisting of 2 new 10 MVA DSC 66 kV: 12.47 kV transformers. There are 2 new 12.47 kV switchgear line-ups, new building of substation and civil work sites. There is installation of 3 new 12.47 kV, 266.8 kcmil lines of transmission being fed out from new substations or switchyards. Financials and schedules of project: Cost controlling budgets and scope definition of project estimates has been completed thereby by AMPS services. Cost controlling budgets were estimated at Dollar 3.59 million. Total actual inclusive project’s completion costs were Dollar 3.62 million. EPCM projects schedules were in turn developed by services of AMPS. Scheduled beginning date was 2010, January 15. Completion date was 2010, September 17. Project completion’s actual date was 2010, September 2. This was with total plant down timing of 14 hours. Project’s beginning schedules and plant’s out aging down timing was reduced both with engineering innovative and effective construction/project management.

Objectives: EPCM’s newly increased capacities switchyards or substations have capabilities to run mining sites from plenty of feeds. This minimizes down time potentially by maintaining high levels of configurability. There is responsibility for all electrical, civil, mechanical and structural design being detailed. Sub-consultants of mechanical, civil and structural engineering are managed, employed and directed by AMPS services. There are responsibilities for nearly all electrical, civil, mechanical and structural management of construction, commissioning or testing, site safety and QC and QA programs. There has to be regulation of line voltages at 12.47 kV because of high incoming voltage variations being supplied from the MB Hydro. There has to be redundancies of control powers by means of using numerous UPS modules and transfer automatic switches. There has to be future expansion capabilities of 3rd DSC transformers and switch gearing with no modification of building. There has to be full customization of data recording and trip settings by means of usages of GE Multilin 750 Feeder Management Relays. There has to be minimization of mined site downstream step stations and hazards of touch by means of usages of grounding of high resistances. There has to be minimization of reduced schedules and out aging times for meeting falls of 2010 plant expansion requirements of power.

66 kV Switch Yards or substations are parts of electrical distribution, generation and transmission systems. Switch yards transforms voltages from high to low or reversed or performing many other crucial functions. In between consumer and generating switch yards, electric powers flow by means of many substations at varied voltage levels. Switch yards are operated and owned by electrical utilities. They may also be owned by large commercial or industrial customer. Switch yards generally are unattended. They rely on SCADA for control and supervision remotely. Switchyards include transformers for changing voltage levels in between low distribution voltage and high transmission’s voltage. This can be at interconnections of 2 varied voltages of transmission. Term switch yard is derived from days before distribution systems became grids. Whilst central generation’s station had become large, small generating plant had been converted to stations of distribution. This receives energy supplies from large plants in place of using own generator. 1st switchyard was connected only to 1 power station. In this generators had been housed with subsidiaries of those power stations. Elements of switch yards: They have generally transformers, switching, and controlling and protection equipment.

In large switchyards, there is usage of circuit breakers for interrupting short circuits or currents overloaded which occurs on network. Small distribution switch yards use recloser circuit fuses or breakers for protecting circuits of distribution.

What do you mean by Quality of Electrical Power?

Quality of Electrical Power determines electric power fitness to consumer devices. Frequency phase and voltage’s synchronization in turn allows functioning of electrical systems. This is in intended manner with no significant life loss or performance loss. Terms are used for describing electric powers. This drives electrical load and ability of load for proper functioning. With no power proper, electrical loads or electrical devices might malfunction, prematurely fail or having no operation at all. There are lots of ways where electrical power is poor quality. There are lots of causes of poor like this power quality. Industry of electric power in turn comprise of AC power, electricity generation, power distribution electrically, and ultimately electric power distribution. This is situated at premises of end users of electrical powers. Electricity moves by means of wiring systems of end users till load is reached. System complexity moves electrical energy from production point to consumption point. It is combined with demand, weather and generation variations and different factors providing lots of opportunities for compromise in supply quality.

Whilst “power quality” is term convenient for many, but it is voltage quality rather than electric current or power which actually is described by terms. Power simply is energy flow and load demanded current which cannot be largely controlled. Quality of Electrical Power is described by parameters values set like harmonic contents in AC power waveforms, service continuity, transient currents and voltages and variation in magnitude of voltages. Power quality is thought as having problem of compatibility. It is equipment being connected to grids. It is compatible with grid events. Power is delivered by grids. This includes events having equipment compatibility with connections. There are 2 solutions at least for compatibility problems. In these cases there is power clean up either or making tougher equipment. Data processing tolerance equipment to variations in voltages is characterized often by CBEMA curves. It gives magnitude and duration of variations in voltages which could be tolerated. AC voltage ideally has been utility supplied as sinusoidal. This has frequency and amplitude provided by standards nationally (in cases of mains) or specifications of system (in cases of power feeds no attached directly to mains). There are impedances of 0 ohms in each and every frequency.

No power source real-life is ideal. It deviates generally in these ways following: Variations in RMS voltage or peak voltage are important both to various equipment types. When RMS voltages exceed nominal voltages by 10% to 80% for 0.5 cycles to 1 minute, event is known as “swell”. “Sag” or a “dip” (equivalent terms) is situation opposite. RMS voltages are below nominal voltages by 10% to 90% for 0.5 cycles to 1 minute. Repetitive or random RMS voltage variation is in between 90% and 110% of nominal. This produces phenomenon called “flicker” in equipment of lighting. This flicker is visible with rapid changes of light levels. Characteristic definition of fluctuation of voltages produces light flicker objectionable being subjected to research on-going. Very briefed abrupt voltage increase known as “surges”, “spikes” or “impulses” caused generally by vast inductive loads. These are turned off or very severely by lighting. Power conditioning is modification of power for improving its quality. Power supply uninterruptible is used for switching off of power mains in case there are temporary or transient conditions on lines. Cheap UPS units, however, creates poor quality power by themselves. This is akin for imposing low amplitude and high frequency square wave atop sine wave. UPS high quality units utilize topologies of double conversions that break down AC incoming power to DC. It charges batteries. Then it re-manufactures AC sine waves.

SEL-751A Feeder Protective Relay – Overview and Applications

SEL-751A Feeder Protection Relay is correct solution for utility and industrial feeder protection. This is with easy mountings, fast settings and flexible input-output options. This provides total feeder protections with frequency, overcurrent, undervoltage and overvoltage elements. This is that protection which can be easily upgraded with no drilling or cutting cutouts existing with multiple adapters of mounting and small formed factors. This integrates quickly serial-or Ethernet based communications with MIRRORED BITS, DeviceNet and IEC 61850 and others.

Overview: Feeder Protection completely: There should be maximization of control schemes flexibility by making use of instantaneous- and time- frequency, overcurrent, undervoltage and overvoltage elements with failure breaker protection for one 3 pole breaker. Protection features optional: There must be making use of SEL-751A with one of input voltage options for providing arc flash detection, DC station battery monitoring, demand and power metering elements and synchronism check. Controls conveniently: There are making use of 4 programmable pushbuttons on front panels for personalized quick controls. Communications easy: You can choose and pick multiple sessions of MODBUS TCP, DNP3 LAN/WAN, Modbus Serial or DNP3 serial for configuration customized of various applications. Control equation of expanded SELogic: There is making use of logic and math combinations of digital and analog values for applications customized. There is adapting system’s controls on basis of prefault conditions. Latched momentary inputs and scaled analog values for SCADA retrievals. Controls reclosing: There is making use of programmable 4 shot recloser with synchronism optional by checking matches of varied reclosing practices. Design rugged: There is relying on wide industry’s ambient temperatures with operating ranges from -40 degrees to +85 degrees. Notification automatic: There are alert key personnel to automatic problems with SEL-3010 Event Messenger direct supports. Installation easy: There are easy installations to locations existing being using availability of retrofit kits without drilling or cutting. Design flexibly: There is choosing from lots of integration and installation options with small form factors and slide in expansion cards.

Applications: There has to be customization of pushbutton front-panel operation and LED or using default breaker close/trip functions. There has to be personalization of LCD messages by using display event-driven point settings. There has to be creation of control integrated system with varieties of communication and input-output options. There has to be making use of integration and programmable control logic features with communication links for protection and control of remote substations. There has to be making use of reporting being comprehensive for understanding events, maintenance of schedule, detecting unfavourable trends, modifying loads and satisfying information for needed factors of supervisory systems. There has to be inclusion of RTD inputs becoming part of integration of system or having bias protections. There has to be remediating of arc flash hazards with arc flash detection. There has to be analysis of overcurrent protection system’s performance by making use of built in (SER) Sequential Events Recorder. There has to be making use of SEL-5010 Relay Assistant Software or ACSELERATOR QuickSet SEL-5030 for managing relay settings. There has to be installation of protection where required with no ventilation systems or special enclosures. The Class 1, Division 2 certification thereby allows SEL-751A in those locations which are adjacent to vapours, liquids, or hazardous gases. Options: There has to be flexible input-output for system applications and local controls: Base system in turn includes 2 digital inputs and 3 digital outputs. There are 3 card slots for SELECT I/O optional cards.

There has to be communications integrated: SEL-751A in turn offers lots of protocol options and communication media. There has to be versatile communication options for providing fast integrations in existing and new applications both.

DC Arc Furnace – An Overview

DC Arc Furnace comprises typically of cylindrical refractory lined steel shell. This is with cathode (central graphite) electrode being positioned vertically by means of opening in roof centre. Anode connections in furnace’s hearth are in contact directly with molten metal layers. This is covered by molten slag layer. Energy has been supplied through open plasma arc. This is generated in between cathode’s bottom tip and molten slag’s upper surface. Central portion at least of surface of slag is open. Meaning is that, there is no covering by feed materials. Since, furnace is powered electrically there can be attainment of very high temperature (greater than 1500 degrees). Open bath thereby allows feed fine materials being fed to furnaces with no risk of gas blocking emanating by chemical reactions. Fine ores and requirements of too much high temperatures leads one for choosing open arc furnace (DC or AC either). Fine ores allows utilizing bed-fluidized reactor for pre-reduction or pre-heating purposes. These provide energy saving significantly used in conjunction with DC Arc Furnace. In cases of open-arc furnaces, the DC furnaces have lots of benefits over AC furnaces. 1 important benefit in circular furnaces is that there are no arc repulsions in cases of single DC arcs. Whilst in AC cases, arcs repel each other. They flare towards walls. They lead to hot spots on areas of side walls. They are in close proximity to electrodes. DC furnace experiences also low electrode consumption. In DC large furnaces, high currents are carried per electrodes or small electrode is utilized for same current. This is because there is “skin effect” AC in which currents are concentrated in electrodes outer periphery.

Chromite smelting: Chromite has been smelted together with few carbon forms for producing ferrochromium. This is with some CO gas and some slag. DC Arc Furnace operate with open bath, open arc configurations. Therefore, there are no heaped burdens by which reaction gases need escapes. There are molten baths simply to which fine materials are dropped. It immediately almost assimilates molten bath, dissolving and melting into slag phases in which reactions occurs. Furnaces DC arc do not require cokes. There are no burdens above bath. So it does not need porosity which shall otherwise be required. This is benefit very significantly. It allows usage of reductants less costly. This avoids relative coke scarcity and high costs. Power being supplied to furnaces is independent largely of composition of slag. Open electric arcs allows one adjusting power amounts going to furnace without depending on slag’s electrical resistivity. These provide extra freedom degree and extra flexibility of change in unconstrained slag compositions by electrical property. So, chemical activity of important metals changes for achieving high chromium recoveries. Increase typically in recovery of chromium is about 95% in DC Arc Furnace and 85% in AC Furnace. This is very crucial increase. DC Arc Furnace has low electrode consumption. DC Arc process use unagglomerated chromite fines and cheap non-coking coals. This technology of furnace is considered as one of low costly options for ferrochromium production. As natures of power generation change with respect to challenges environmentally more energy renewable are used. There are abilities of swinging furnace loads likely for bringing economic benefits significantly. This is common practice, though it incurs nuisance factors with plant operation. Large furnaces are better than present furnaces with respect to handling powered dips and out aging long times. DC Arc Furnace offers benefits crucial when question of fast and easy load swinging arises. This type of furnace has wonderful features which are proven in industrial practices over past 30 years. They accommodate fine sized feed materials very nicely.

Flexible Alternating Current Transmission System (FACTS) : Technological Overview

(FACTS) meaning Flexible Alternating Current Transmission System or Flexible AC Transmission is a system. This system is composed of static equipment. It is utilized for electrical energy’s transmission AC. It is supposed for enhancing power transfer capabilities and increasing controllability of network. It is power electronic based system generally. FACTS as defined by IEEE are that it is system based on power electronics and different static equipment. It has provision of controlling one or more than one system parameters of AC transmission. It does enhancement of controllability and increasing maximization of power transfer capabilities. FACTS as stated and defined by Siemens are that FACTS increases AC grid’s reliability. This reduces cost of power delivery. This improves power transmission efficiency and quality of transmission. This is by supplying reactive or inductive powers to grids.

Technology: Series compensation: In this series compensation, FACTS are connected with power system in series. It works as voltage controllable source. Inductance series exist in all transmission AC lines. In long lines, when large current flows, then that causes large voltage drops. Capacitors in series are connected for compensation. This decreases inductance effects. By connection of series capacitors being in series with lines, inductive reactance in between sending end and receiving end is reduced. By this system’s power factor is improved. But effects on power factor are too much little as compared with shunt capacitor. Shunt compensation: In this shunt compensation, FACTS are connected with power system in shunt (parallel). This works as controllable sources of current. There are 2 types of shunt compensation: Shunt capacitive compensation: This way has been used for improving power factors. Whenever inductive loads are connected to transmission lines, there is lagging of power factor due to lags in load currents. For compensating this, shunt capacitors are connected. It draws currents being led by source voltages. Net result is power factor improvement. Shunt inductive compensation: This way is either used when transmission line is charged or when low loads are there at receiving end. Since, there is no load or very low load, so very less current flow through transmission lines. Shunt capacitance in transmission lines cause amplification of voltage. This is called Ferranti Effect. Receiving end voltages becomes double of sending end voltage. This is case generally in too much long transmission lines. For compensating this, shunt inductors have been connected through transmission lines. Power transfer capabilities are increased thereby whilst depending on power equations.

Series compensation examples: There is (SSSC) Static synchronous series compensator. There has to be (TCSC) Thyristor-controlled series capacitor: This is where series capacitor banks are shunted by thyristor-controlled reactors. There has to be (TCSR) Thyristor-controlled series reactor: This is where series reactor banks are shunted by thyristor-controlled reactors. There has to be (TCSC) Thyristor-controlled series capacitor: This is where series capacitor banks are shunted by thyristor-controlled reactors. There has to be (TSSC) Thyristor-switched series capacitor: This is where series capacitor banks are shunted by thyristor-switched reactor. There has to be (TSSR) Thyristor-switched series reactor: This is where series reactor banks are shunted by thyristor-switched reactor. Shunt compensation examples: There is (STATCOM) Static synchronous compensator. This was called previously static condenser (STATCON). There has to be (SVC) Static VAR compensator. Common SVC is: (TCR) Thyristor-controlled reactor: This is reactor in series connected with thyristor bidirectional valve. Thyristor valve is controlled by phases. Reactance equivalent is continuously varied. (TSR) Thyristor-switched reactor: It is similar to TCR. But thyristor is in full or zero conduction. Reactance equivalent is in stepwise way varied.

(TSC) Thyristor-switched capacitor: This is capacitor in series connected with thyristor bidirectional valve. But thyristor is in full or zero conduction. Reactance equivalent is in stepwise way varied.

Reactive Power Consumption in Transmission Line

Electric powers have been rates at which electrical energies are transferred by electrical circuits. It could be transformed to different power forms. This is when electrical charge moves by means of electrical potential differences. This occurs in electric circuits in electrical components. In the AC circuits, electrical components that are capacitors and inductors may go under periodical changes in energy flow direction. This thereby gives rise to Reactive power and Active Power. Power portion that was averaged over complete cycles of AC waveforms; result in net energy transfer in one direction. This is called Active Power or Real Power. Power portion that was due to energy stored and that return to sources in all cycles, is called Reactive Power.

When there is passing of electric currents through wires, then there is production obviously of magnetic fields in and around it. When these fields alternate in between peak opposite values in both space and time, then induced voltages are produced. This is in any conductor which lies in path of these fields. These particular fields could react with different magnetic fields being established by different conductors. Mechanical forces are created in between 2 conductors. These alternating fields produce alternating currents. This is on basis to enable us for using extensively the electrical powers. DC currents with non-alternating, steady fields do not offer this benefit. Alternating flux poses lots of problems. One amongst them is reactive power. It is that power which is needed for maintaining and establishing fluctuating AC magnetic flux. This is there with no energy transfers taking place for it. Other than this there is active power. This active power does power delivery in thermal, electrical and mechanical forms and in any other desired forms.

Reactive power Consumption in Transmission Line is necessary thing. Without this system shall not function properly. This is one which poses major problems. Areas of problems linked with fields of AC are hunting torque, reactances, arcs, skin effect, resonances and surges. For overcoming these above mentioned problems, the tool being effective is CAPACITOR. When voltages are placed initially across coils, then magnetic fields are built up. This takes sufficient time for currents for reaching full values. It causes currents lagging behind voltages in phases. Therefore, the devices have been said for being lagging reactive power’s sources. Capacitor in AC devices store energies in forms of electrical fields. When currents are driven by means of capacitors, it takes sufficient time duration for charging. This charging builds up production of full differences of voltages. AC network voltage’s across capacitors changes constantly. Capacitor opposes these changes thereby causing voltages lagging behind currents. Speaking in other words, currents leads voltages in phases. So, the devices are sources of reactive leading powers. Electrical generator supplies reactive power plus active power. This is consumed by loads of customer. Reactive power purposes: Synchronous generators, different types of various (DER) Distributed Energy Resource and SVC equipment are utilized for maintaining voltages all through transmission system. Reactive power injection to system raises voltage. Reactive power absorption lower voltages. Requirements of voltage support are function of magnitudes and location of customer loads, DER configuration transmission system and generator outputs. Requirements substantially differ from one location to other. It rapidly changes as location and magnitude of load and generation changes. At too much lowered levels of system loads, the transmission lines acting as capacitors increases voltages. At load’s high levels, transmission lines lower voltages by absorbing reactive powers. Equipment of transmission system like tap changing transformers is static. But it could be switched for responding to voltage support required changes. Operation of system has some objectives whilst managing voltages and reactive power.

Electric Locomotive – Technological Overview

Electric Locomotive is that locomotive which is powered in turn by electricity by means of third rail, on-board energy storages like fuel cell or battery or the overhead lines. Electric Locomotives along with on-board prime fueled movers like gas turbines or diesel engines are classified as gas turbine- or diesel- electric locomotives. Reason is that electric motor/ generator combination only serves as system of power transmission. Electricity has been used for eliminating smoke and taking benefits of high efficiency of electric motors. But electrification costs have meaning that only usually heavy used lines are electrified. Electric Locomotive is supplied with powers from ultracapacitor-mining powered locomotives or rechargeable energy storage systems or stationary sources. Designing features distinguishing of Electric Locomotive is: Electrical power types used DC or AC. Storing ways (ultracapacitors, batteries) or transmission (collecting) electrical powers. Means used for coupling traction motors to drivers (driving wheels).

Alternating current and direct current: Most important differences lie in choices of DC or AC. Early systems used DC as AC had not been understood nicely. Insulation materials for high lines of voltage are not available. The DC locomotives run typically at relative low voltages (600 volts to 3000 volts). Equipment is relatively massive therefore since involved currents are large for transmitting power sufficient. Power is supplied at intervals frequently as high current results in system losses of large transmission. AC motors have been developed. They had become predominant types. This is on long routes particularly. High voltages (10s of 1000s of volts) have been used since these allow uses of low currents. Transmission losses have been proportional to square of current, meaning 2 times current means 4 times loss. High powers are conducted over longer distances on light and cheap wires. The transformers in locomotives transform power to low voltages and high currents for motors. Same low current high voltage system is employed with locomotives of DC. There are no easy ways of doing current/voltage transformation for DC. This is efficient as got by AC transformers.

Transmission of power: Electrical circuits need 2 connections or 3 connections for 3 phase AC. From beginning, tracks are used for 1 circuit side. Unlike railroads model track supplies normally 1 side only. Other circuit side is separately provided. Original electrification of Baltimore and Ohio Railroad uses sliding shoe in overhead channels. This system found quickly being unsatisfactory. This was by third rail replaced. In this, “shoe” (pickup) rode on top or underneath of small rail paralleled to main tracks on top of ground level is there. Multiple pickups are there on 2 sides of locomotives for break accommodation in third rail. This is needed by trackwork. System is thereby preferred in the subway since it affords close clearances. Railways prefer overhead lines called often “catenaries” after support system is used for holding wires paralleled to ground. 3 collection ways are possible: Bow collector: It is frame which holds long collecting rods against wires. Pantograph: It is hinged frame which holds collecting shoe against wires in fixed geometries. Trolley Pole: It is flexible long pole that engages line with shoe or wheel. Driving wheels: During developments initially of electrical railroad propulsion, plenty of drive systems had been devised for coupling output of traction motors to wheels. Locomotive early often used jackshaft drives. In arrangement like this, traction motors are mounted inside locomotive body and drives jackshaft by means of gear’s set. System had been employed since 1st traction motors are too heavy and large for direct mountings on axles. Plenty of mechanical parts are involved. Frequent maintenance is necessary. Jackshaft drives are abandoned for all. But small units when light and small motors were developed.


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