Power Engineering Guide Transmission and Distribution4th EditionPower Engineering Guide Transmission and DistributionYour local representative:Sales locations worldwide (EV): http://www.ev.siemens.de/en/pages/salesloc.htmDistributed by: Siemens Aktiengesellschaft Power Transmission and Distribution Group International Business Development, Dept. EV IBD P.O. Box 3220 D-91050 Erlangen Phone: ++ 49 - 9131-73 45 40 Fax: ++ 49-9131-73 45 42 Power Transmission and Distribution group online: http://www.ev.siemens.deSiemens Power Engineering Guide Transmission and Distribution 4th EditionForewordThis Power Engineering Guide is devised as an aid to electrical engineers who are engaged in the planning and specifying of electrical power generation, transmission, distribution, control, and utilization systems. Care has been taken to include the most important application, performance, physical and shipping data ofthe equipment listed in the guide which is needed to perform preliminary layoutand engineering tasks for industrial and utility-type installations. The equipment listed in this guide is designed, rated, manufactured and tested in accordance with the International Electrotechnical Commission (IEC) recommendations. However, a number of standardized equipment items in this guide are designed to take other national standards into account besides the above codes, and can be rated and tested to ANSI/ NEMA, BS, CSA, etc. On top of that, we manufacture a comprehensive range of transmission and distribution equipment specifically to ANSI/NEMA codes and regulations. Two thirds of our product range is less than five years old. For our customers this means energy efficiency, environmental compatibility, reliability and reduced life cycle cost. For details, please see the individual product listings or inquire. Whenever you need additional information to select suitable products from this guide, or when questions about their application arise, simply call your local Siemens office. Sales locations worldwide: http://www.ev.siemens.de/en/pages/ salesloc.htmSiemens AG is one of the worlds leading international electrical and electronicscompanies. With 416 000 employees in more than 190 countries worldwide, the company is divided into various Groups. One of them is Power Transmission and Distribution. The Power Transmission and Distribution Group of Siemens with 24 700 employees around the world plans, develops, designs, manufactures and markets products, systems and complete turn-key electrical infrastructure installations. Thegroup owns a growing number of engineering and manufacturing facilities in morethan 100 countries throughout the world. All plants are, or are in the process of being certified to ISO 9000/9001 practices. This is of significant benefit forour customers. Our local manufacturing capability makes us strong in global sourcing, since we manufacture products to IEC as well as ANSI/NEMA standards in plants at various locations around the world. Siemens Power Transmission and Distribution Group (EV) is capable of providing everything you would expect from an electrical engineering company with a global reach. The Power Transmission and Distribution Group is prepared and competent, to perform all tasks and activitiesinvolving transmission and distribution of electrical energy.Siemens Power Transmission and Distribution Group offers intelligent solutions for the transmission and distribution of power from generating plants to customers. The Group is a product supplier, systems integrator and service provider, andspecializes in the following systems and services: s High-voltage systems s Medium-voltage systems s Metering s Secondary systems s Power systems control and energy management s Power transformers s Distribution transformers s System planning s Decentralized power supply systems. Siemens service includes the setting upof complete turnkey installations, offers advice, planning, operation and training and provides expertise and commitment as the complexity of this task requires. Backed by the experience of worldwide projects, Siemens can always offer itscustomers the optimum cost-effective concept individually tailored to their needs. We are there wherever and whenever you need us to help you build plants better, cheaper and faster.Dr. Hans-Jrgen Schlo Vice President Siemens Aktiengesellschaft Power Transmissionand DistributionSiemens Power Engineering Guide Transmission and Distribution 4th EditionQuality and Environmental PolicyQuality and Environmental Our first priority Transmission and distribution equipment from Siemens means worldwide activities in engineering, design, development, manufacturing and service. The Power Transmission and Distribution Group of Siemens AG, with all of its divisions and relevant locations, has been awarded andmaintains certification to DIN EN ISO 9001 and DIN EN ISO 14001. Certified quality Siemens Quality Management and Environmental Management System gives our customers confidence in the quality of Siemens products and services. Certified tobe in compliance with DIN EN ISO 9001 and DIN EN ISO 1400, it is the registeredproof of our reliabilty.Siemens Power Engineering Guide Transmission and Distribution 4th EditionContentsGeneral Introduction Energy Needs Intelligent SolutionsPower Transmission Systems1High Voltage2Medium Voltage3Low Voltage4Transformers5Protection and Substation Control6Power Systems Control and Energy Management7Metering8Services9System Planning10Conversion Factors and Tables Contacts and Internet Addresses Conditions of Sales and DeliverySiemens Power Engineering Guide Transmission and Distribution 4th EditionGeneral IntroductionEnergy management systems are also important, to ensure safe and reliable operation of the transmission network. Distribution In order to feed local medium-voltage distribution systems of urban, industrial or rural distribution areas, HV/MVmain substations are connected to the subtransmission systems. Main substationshave to be located next to the MV load center for reasons of economy. Thus, thesubtransmission systems of voltage levels up to 145 kV have to penetrate even further into the populated load centers. The far-reaching power distribution system in the load center areas is tailored exclusively to the needs of users with large numbers of appliances, lamps, motor drives, heating, chemical processes, etc. Most of these are connected to the low-voltage level. The structure of the low-voltage distribution system is determined by load and reliability requirementsof the consumers, as well as by nature and dimensions of the area to be served.Different consumer characteristics in public, industrial and commercial supplywill need different LV network configurations and adequate switchgear and transformer layout. Especially for industrial supply systems with their high number ofmotors and high costs for supply interruptions, LV switchgear design is of great importance for flexible and reliable operation. Independent from individual supply characteristics in order to avoid uneconomical high losses, however, the substations with the MV/LV transformers should be located as close as possible tothe LV load centers. The compact load center substations should be installed right in the industrial production area near to the LV consumers. The superposed medium-voltage system has to be configured to the needs of these substations and the available sources (main substation, generation) and leads again to differentsolutions for urban or rural public supply, industry and large building centers.In addition distribution management systems can be tailored to the needs, fromsmall to large systems and for specific requirements.Main substation with transformers up to 63 MVAHV switchgear MV switchgearLocal medium-voltage distribution systemRing type Public supplyFeeder cable Connection of large consumerSpot system Industrial supply and large buildingsMedium voltage substationsMV/LV substation looped in MV cable by load-break switchgear in different combinations for individual substation design, transformers up to 1000 kVA LV fuses Circuitbreaker Loadbreak switch Consumer-connection substation looped in or connected to feeder cable with circuitbreaker and load-break switches for connection of spot system in different layoutMV/LV transformer levelLow-voltage supply systemPublic supply with pillars and house connections internal installation Large buildings with distributed transformers vertical LV risers and internal installation per floor Industrial supply with distributed transformers with subdistributionboard and motor control centerConsumersFig. 2: Distribution: Principle configuration of distribution systemsSiemens Power Engineering Guide Transmission and Distribution 4th EditionGeneral IntroductionDespite the individual layout of networks, common philosophy should be an utmostsimple and clear network design to obtain s flexible system operation s clear protection coordination s short fault clearing time and s efficient system automation. The wide range of power requirements for individual consumers from a few kW to some MW, together with the high number of similar network elements, are themain characteristics of the distribution system and the reason for the comparatively high specific costs. Therefore, utmost standardization of equipment and use of maintenance-free components are of decisive importance for economical system layout. Siemens components and systems cater to these requirements based on worldwide experience in transmission and distribution networks. Protection, operation, control and metering Safe, reliable and economical energy supply is also amatter of fast, efficient and reliable system protection, data transmission andprocessing for system operation. The components required for protection and operation benefit from the rapid development of information and communication technology. Modern digital relays provide extensive possibilities for selective relaysetting and protection coordination for fast fault clearing and minimized interruption times. Remote Terminal Units (RTUs) or Substation Automation Systems (SAS) provide the data for the centralized monitoring and control of the power plants and substations by the energy management system. Siemens energy management systems ensure a high supply quality, minimize generation and transmission costs and optimally manage the energy transactions. Modularity and open architecture offer the flexibility needed to cope with changed or new requirements originating e.g. from deregulation or changes in the supply area size. The broad range of applications includes generation control and scheduling, management of transmissionand distribution networks, as well as energy trading. Metering devices and systems are important tools for efficiency and economy to survive in the deregulatedmarket. For example, Demand Side Management (DSM) allows an electricity supplyutility from a control center to remotely control certain consumers on the supply network for load control purposes. Energy meters are used for measuring the consumption of electricity, gas, heat and water for purposes of billing in the fields of households, commerce, industry and grid metering.Power system substationPower system switchgear Bay protection Overcurrent Distance Differential etc. Other bays Bay coordination level Bay switching interlocking Control Other baysSubstation coordination level BB and BF (busbar and breaker failure) protectionSwitchgear interlocking Substation control Data processing Automation MeteringData and signal input/outputOther substationsPower network telecommunication systemsOther substationsPower line carrier communicationFiber-optic communicationSystem coordination levelSCADA functions Distribution management functions Grafical information systems Network analysisPower and scheduling applicationsTraining simulatorControl room equipmentFig. 3: System Automation: Principle configuration of protection, control and communication systemsSiemens Power Engineering Guide Transmission and Distribution 4th EditionGeneral IntroductionOverall solutions System planning Of crucial importance for the quality of powertransmission and distribution is the integration of diverse components to formoverall solutions. Especially in countries where the increase in power consumption is well above the average besides the installation of generating capacity, construction and extension of transmission and distribution systems must be developed simultaneously and together with equipment for protection, supervision, control and metering. Also, for the existing systems, changing load structures, changing requirements due to energy market deregulation and liberalization and/ or environmental regulations, together with the need for replacement of aged equipment will require new installations. Integral power network solutions are far morethan just a combination of products and components. Peculiarities in urban development, protection of the countryside and of the environment, and the suitability for expansion and harmonious integration in existing networks are just a fewof the factors which future-oriented power system planning must take into account. Outlook The electrical energy supply (generation, transmission and distribution) is like a pyramid based on the number of components and their widespread use. This pyramid rests on a foundation formed by local expansion of the distribution networks and power demand in the overall system, which is determined solely by the consumers and their use of light, power and heat. These basic applicationsarise in many variations and different intensities throughout the entire private, commercial and industrial sector (Fig. 4). Reliability, safety and quality (i.e. voltage and frequency stability) of the energy supply are therefore absoluteessentials and must be assured by the distribution networks and transmission systems.Generation Transmission Distribution ConsumersApplicationsLightPowerHeatMonitoring, Control, AutomationFig. 4: Industrial applicationsSiemens Power Engineering Guide Transmission and Distribution 4th EditionEnergy Needs Intelligent SolutionsThe changing state of the worlds energy markets and the need to conserve resources is promoting more intelligent solutions to the distribution of mans silent servant, electricity. Change is generally wrought by necessity, often driven by a variety of factors, not least social, political, economic, environmental and technological considerations. Currently the worlds energy supply industries principally gas and electricity are in the process of undergoing radical and crucial change that is driven by a mixture of all these considerations. The collective name given to the factors affecting the electricity supply industry worldwide is deregulation. This is the changing operating scenario the electricity supply industryas a whole faces as it moves inexorably into the 21st century. How can it riseto the challenge of liberalized markets and the opportunities presented by deregulation? One of the answers is the better use of information technology and intelligent control to affect the necessary changes born of deregulation. However, toachieve this utilities need to be very sure of the technical and commercial competence of their systems suppliers. Failure could prove to be very costly not just in financial terms, but also for a utilitys reputation with its consumers in what is becoming increasingly a buyers market. Forming and maintaining close partnerships with long-established systems suppliers such as Siemens is the best way of ensuring success with deregulation into the millennium. Siemens can look backon over 100 years of working in close co-operation with power utilities throughout the world. This accumulated experience allows the companys Power Transmissionand Distribution Group to address not just technical issues, but also better appreciate many of the operational and commercial aspects of electricity distribution. Experience gained over the past decade with the many-and-varied aspects of deregulation puts the Group in an almost unique position to advise utilities as to the best solutions for taking full advantage of the opportunities offered by deregulation. Innovation the issue of change Although todays technology obviouslyplays a very important role in the companys current business, innovation has always been at the vanguard of its activities; indeed it is the common thread that has run through the company since its inception 150 years ago. In future power distribution technology, computer software, power electronics and superconductivity will play increasingly prominent roles in innovative solutions. Scope for newtechnolFig. 5: Superconducting current limiter: lightning fast responseogies is to be found in decentralized energy supply concepts and in meeting theneeds of urban conurbations. Siemens is no longer just a manufacturer of systemsand equipment, it is now much more. Overall concepts are becoming ever more important. All change! Power distribution technology has not changed significantlyover the past forty years indeed, the rules of the game have remained the same fora much longer period of time. A new challenge Recently decentralized power supply systems have cornered a growing share of the market for a number of reasons. In developing and industrializing countries, it has become clear that the energypolicies and systems solutions adopted by nations with well-established energy infrastructures are not always appropriate. Frequently it is more prudent to start with small decentralized power networks and to expand later in a progressive way as demand and economics permit. Much benefit can also be gained if generationmakes use of natural or indigenous resources such as the sun, water, wind or biomass. Countries that struggle with population growth and migration to the townsand cities clearly need to pay close attention to protecting their balance of payments. In such cases, the expansion of power supplies into the countrysideis a crucial factor in the economic and social development of a particular country. In the industrialized countries the concept of the decentralized power supplyis also gaining ground, largely because of environmental concern. This has had its consequences for the generation of electricity: wind power is experiencing arenaissance, more development work is being carried out into photovoltaic devices and combined heat and power cogeneration plants are growing in popularity in many areas for both ecological and economic reasons. These developments are resulting in some entirely new energy network structures. Additional tasks... The scope and purpose of tomorrows distribution systems will no longer be to simply supply electricity. In future they will be required to harvest power and redistribute itmore economically and take into account, among other considerations, environmental needs. In the past it was no easy task to supply precisely the right amountof electricity according to demand because, as is well-known, electricity cannotbe readily stored and the loads were continually changing. Demand scheduling was very much based on statistical forecasting not an exact science and one that cannot by its very nature take into account realtime variations. Demand scheduling problems can become particularly acute when power stations of limited generating capacity are on line.Siemens Power Engineering Guide Transmission and Distribution 4th EditionEnergy Needs Intelligent SolutionsNowadays these and similar problems are not insoluble because of decentralized power supplies and the use of intelligent control. The Power Transmission and Distribution Group has developed concepts for the economic resolution of peak energydemand. One is to use energy stores. Batteries are an obvious choice, for thesecan be equipped with power electronics to enhance energy quality as well as storing electricity. Intelligent energy management One of the options for matching the amount of electricity available to the amount being demanded is, even today, the rarely used technique of load control. Energy saving can mean much more thanjust consuming as few kilowatt-hours as possible. It can also mean achieving theflexibility of demand that can make a valuable contribution to a countrys economy. Naturally, in places such as hospitals, textile factories and electronic chipfabrication plants it is extremely important for the power supply not to fail not even for a second. In other areas of electricity consumption, however, thereis much more room for manoeuvre. Controlled interruptions of a few minutes, andeven a few hours, can often be tolerated without causing very much difficulty tothose involved. There are other applications where the time constant or resilience is high, e.g. cold stores and air-conditioning plants, where energy can be stored for periods of up to several hours. Through the application of intelligent control and with suitable financial encouragement (usually in the form of flexible tariff rates) there is no doubt that very much more could be made of load control. Improving energy quality Power electronics systems, for example SIPCON, canhelp improve energy quality an increasingly important factor in deregulated energy markets. Energy has now become a product. It has its price and a defined quality. Consumers want a definite quality of energy, but they also produce reactioneffects on the system that are detrimental to quality (e.g. harmonics or reactive power). Energy quality first has to be measured and documented, for example with the SIMEAS family of quality recorders. These measurements are important forprice setting, and can serve as the basis for remedial action, such as with active or passive filters. Power electronics development has opened up many new possibilities here, although considerable progress may still be made in this area abreakthrough in silicon carbide technology, for example.Fig. 6: Silicon carbideFig. 7: GILAlternatives It should be appreciated, however, that decentralized power suppliesare not a panacea. For those places where energy density requirements are high,large power stations are still the answer, and especially when they can supplydistrict heating. Theoretically, it should still be possible to employ conventional technology to transport very large amounts of electricity to the megacitiesof the 21st Century. Even if the use of overhead power lines was not an option,due to say there being insufficient space orresistance from people living nearby, it would be possible to use gas-insulatedlines (GIL), an economical alternative investigated by Siemens. The developmentaim of reducing costs has meanwhile been attained here, and costeffective applications involving distances of serveral kilometres are therefore possible. The system costs for the gas-insulated transmission lines (GIL) developed by Siemens exceed those of overhead lines only by about a factor of 10.Siemens Power Engineering Guide Transmission and Distribution 4th EditionEnergy Needs Intelligent SolutionsEnergy management via satelliteLong-distance DC transmission Wind energy Solar energy Converter stationPower plants Pumping stationBiomass power plantIrrigation systemSwitching station Energy store GIL Distribution stationFuel cellsCooling station (liquid nitrogen)Fig. 8: The mega-cities of the 21st century and the open countryside will need different solutions very high values of connection density in the former and decentralised configurations in the latterThis has been achieved by laying the tubular conductor using methods similar tothose employed with pipelines. Savings were also made by simplifying and standardizing the individual components and by using a gas mixture consisting of sulfurhexafluoride (SF6) and nitrogen (N2). The advantages of this new technology arelow resistive and capacitive losses. The electric field outside of the enclosure is zero, and the magnetic field is negligibly small. No cooling and no phase angle compensation are required. GILs are not a fire hazard and are simple to repair. Energy trade The new rules of the game that are being introduced in power supply business everywhere are demanding more capability from utility IT systems, especially in areas such as energy trading. Siemens has been in the fortunate position of being able to accumulate early practical experience in this field in markets where deregulation is being introduced very quickly such as the United Kingdom, Scandinavia and the USA and so is now able to offer sophisticated systemsand expertise with which utilities can get to grips with the demands of the newcommercial environment. In the past it was always security of supply that took the highest priority for a utility. Now, however, although it remains an important subject, more and more shareholders are demanding a more reasonable return on their investment. Deregulation generally means privatization; profit orientation is therefore clearly going to take over from concern with cost. In addition this means that competition will inevitably produce some concessions in the price of electricity, which will increasethe pressure on energy suppliers. Many power supply companies are striving to introduce additional energy services, thereby making the pure price of energy notthe only yardstick their customers apply when deciding how to make their purchases.nies and independent operating utilities will no longer confine their activitiesto just energy production; they will be expected to become increasingly involved in energy distribution too. Potential for the future The ongoing development of high-temperature superconductors will doubtless enable much to be achieved. Major operational innovations will, nonetheless, come from the more pervasive useof communications and data systems two areas of technology where innovations canbe seen every 18 months. Consequently, it will be from these areas that the enabling impetus for significant advances in power engineering will come.Siemens the energy systems house Siemens is offering solutions to the problems that are governed by the new rules of the game. The company possesses considerableexpertise, mainly because it is a global player, but also because it covers thetotal spectrum of products necessary for the efficient transmission and distribution of electricity. As with other Groups within the company, Power Transmissionand Distribution no longer regards itself as simply a purveyor of hardware. Infuture Siemens will be more of a provider of services and total solutions. Thiswill mean embracing many new disciplines and skills, not least financial controland complete project management. One of the reasons is that in future BOT (Build,Operate & Transfer) compaSiemens Power Engineering Guide Transmission and Distribution 4th EditionHigh VoltageContentsPageIntroduction ...................................... 2/2 Air-Insulated Outdoor Substations ....................... 2/4 Circuit-Breakers General ............................................. 2/10 Circuit-Breakers 72 kV up to 245 kV .......................... 2/12 Circuit-Breakers 245 kV up to 800 kV ........................ 2/14 Live-Tank Circuit-Breakers .......... 2/16 Dead-Tank Circuit-Breakers ........ 2/20 Surge Arresters .............................. 2/24 Gas-Insulated Switchgear for Substations Introduction ..................................... 2/28 Main Product Range ..................... 2/29 Special Arrangements .................. 2/33 Specification Guide ....................... 2/34 Scope of Supply ............................. 2/37 Gas-insulated Transmission Lines (GIL) .............. 2/38 Overhead Power Lines ................. 2/40 High-Voltage Direct Current Transmission .................... 2/49 Power Compensation in Transmission Systems .................. 2/522High-Voltage Switchgear for SubstationsIntroduction 1High-voltage substations form an important link in the power transmission chainbetween generation source and consumer. Two basic designs are possible: Air-insulated outdoor switchgear of open design (AIS) AIS are favorably priced high-voltage substations for rated voltages up to 800 kV which are popular wherever spacerestrictions and environmental circumstances do not have to be considered. Theindividual electrical and mechanical components of an AIS installation are assembled on site. Air-insulated outdoor substations of open design are not completely safe to touch and are directly exposed to the effects of weather and the environment (Fig. 1). Gas-insulated indoor or outdoor switchgear (GIS) GIS compact dimensions and design make it possible to install substations up to 550 kV right in the middle of load centers of urban or industrial areas. Each circuitbreaker bay is factory assembled and includes the full complement of isolator switches, grounding switches (regular or make-proof), instrument transformers, control andprotection equipment, interlocking and monitoring facilities commonly used for this type of installation. The earthed metal enclosures of GIS assure not only insensitivity to contamination but also safety from electric shock (Fig. 2). Gas-insulated transmission lines (GIL) A special application of gas-insulated equipment are gas-insulated transmission lines (GIL). They are used where high-voltageoverhead lines are not suitable for any reason. GIL have a high power transmission capability, even when laid underground, low resistive and capacitive losses and low electromagnetic fields.234Fig. 1: Outdoor switchgear5678910Fig. 2: GIS substations in metropolitan areas2/2Siemens Power Engineering Guide Transmission and Distribution 4th EditionHigh-Voltage Switchgear for SubstationsTurnkey Installations High-voltage switchgear is normally combined with transformers and other equipment to complete transformer substations in order to s Stepup from generator voltage level to high-voltage system (MV/HV) s Transform voltage levels within the high-voltage grid system(HV/HV) s Step-down to medium-voltage level of distribution system (HV/MV) The High Voltage Division plans and constructs individual high-voltage switchgear installations or complete transformersubstations, comprising high-voltage switchgear, medium-voltage switchgear, major components such as transformers, and all ancillary equipment such as auxiliaries, control systems, protective equipment, etc., on a turnkey basis or even as general contractor. The spectrum of installations supplied ranges from basic substations with single busbar to regional transformer substations with multiple busbars or 1 1/2 circuit-breaker arrangement for rated voltages up to 800 kV, ratedcurrents up to 8000 A and short-circuit currents up to 100 kA, all over the world. The services offered range from system planning to commissioning and after-sales service, including training of customer personnel. The process of handlingsuch an installation starts with preparation of a quotation, and proceeds through clarification of the order, design, manufacture, supply and cost-accounting until the project is finally billed. Processing such an order hinges on methodicaldata processing that in turn contributes to systematic project handling. All these high-voltage installations have in common their high-standard of engineering, which covers power systems, steel structures, civil engineering, fire precautions, environmental protection and control systems (Fig. 3). Every aspect of technology and each work stage is handled by experienced engineers. With the aid ofhigh-performance computer programs, e.g. the finite element method (FEM), installations can be reliably designed even for extreme stresses, such as those encountered in earthquake zones. All planning documentation is produced on modern CADsystems; data exchange with other CAD systems is possible via standardized interfaces. By virtue of their active involvement in national and international associations and standardization bodies, our engineers are1Major components, e.g. transformer Substation Control Control and monitoring, measurement, protection, etc. Structural Steelwork Gantries and substructures Civil Engineering Buildings, roads, foundationsEnvFire protection iron pro menta tec tion l23DesignAC/DC es ri auxililiaab les Contro l and signal c ableswerge s Su erter div g in th a r te m E s syAncillary equipment4Lightnion lat n ti Ve frequ. Carrier- ent equipmrcingPo5Fig. 3: Engineering of high-voltage switchgear6Know how, experience and worldwide presence A worldwide network of liaison and sales offices, along with the specialist departments in Germany, support and advise our customers in all matters of switchgear technology. Siemens has for many years been a leading supplier of high-voltage equipment, regardless of whether AIS, GIS or GIL has been concerned. For example, outdoor substations of longitudinal in-line design are still known in many countries under the Siemens registeredtradename Kiellinie. Back in 1968, Siemens supplied the worlds first GIS substation using SF6 as insulating and quenching medium. Gas-insulated transmission lineshave featured in the range of products since 1976.always fully informed of the state of the art, even before a new standard or specification is published. Quality/Environmental Management Our own high-performance, internationally accredited test laboratories and a certified QM system testify to the quality of our products and services. Milestones: s 1983: Introductionof a quality system on the basis of Canadian standard CSA Z 299 Level 1 s 1989:Certification of the SWH quality system in accordance with DIN EN ISO 9001 by the German Association for Certification of Quality Systems (DQS) s 1992: Repetition audit and extension of the quality system to the complete EV H Division s 1992: Accreditation of the test laboratories in accordance with DIN EN 45001 by the German Accreditation Body for Technology (DATech) s 1994: Certification of theenvironmentalsystems in accordance with DIN EN ISO 14001 by the DQS s 1995: Mutual QEM Certificate78910Siemens Power Engineering Guide Transmission and Distribution 4th Edition2/3Design of Air-Insulated Outdoor SubstationsStandards 1Air-insulated outdoor substations of open design must not be touched. Therefore,air-insulated switchgear (AIS) is always set up in the form of a fenced-in electrical operating area, to which only authorized persons have access. Relevant IEC 60060 specifications apply to outdoor switchgear equipment. Insulation coordination, including minimum phaseto-phase and phase-to-ground clearances, is effected in accordance with IEC 60071. Outdoor switchgear is directly exposed to the effects of the environment such as the weather. Therefore it has to be designed based on not only electrical but also environmental specifications. Currently there is no international standard covering the setup of air-insulated outdoor substations of open design. Siemens designs AIS in accordance with DIN/VDE standards, in line with national standards or customer specifications. The German standard DIN VDE 0101 (erection of power installations with rated voltages above 1 kV)demonstrates typically the protective measures and stresses that have to be taken into consideration for airinsulated switchgear. Protective measures23Stresses s Electrical stresses, e.g. rated current, short-circuit current, adequate creepage distances and clearances s Mechanical stresses (normal stressing),e.g. weight, static and dynamic loads, ice, wind s Mechanical stresses (exceptional stresses), e.g. weight and constant loads in simultaneous combination with maximum switching forces or shortcircuit forces, etc. s Special stresses, e.g. caused by installation altitudes of more than 1000 m above sea level, or earthquakesVariables affecting switchgear installationSwitchgear design is significantly influenced by: s Minimum clearances (depending on rated voltages) between various active parts and between active parts and earth s Arrangement of conductors s Rated and short-circuit currents s Clarity for operating staff s Availability during maintenance work, redundancy s Availability of land and topography s Type and arrangement of the busbar disconnectors The design of a substation determines its accessibility, availability and clarity.The design must therefore be coordinated in close cooperation with the customer. The following basic principles apply: Accessibility and availability increasewith the number of busbars. At the same time, however, clarity decreases. Installations involving single busbars require minimum investment, but they offer onlylimited flexibility for operation management and maintenance. Designs involving1 1/2 and 2 circuit-breaker arrangements assure a high redundancy, but they also entail the highest costs. Systems with auxiliary or bypass busbars have provedto be economical. The circuit-breaker of the coupling feeder for the auxiliarybus allows uninterrupted replacement of each feeder circuit-breaker. For busbarsand feeder lines, mostly wire conductors and aluminum are used. Multiple conductors are required where currents are high. Owing to the additional shortcircuitforces between the subconductors (pinch effect), however, multiple conductors cause higher mechanical stressing at the tension points. When wire conductors, particularly multiple conductors, are used higher short-circuit currents cause a rise not only in the aforementioned pinch effect but in further force maxima in the event of swinging and dropping of the conductor bundle (cable pull). This in turn results in higher mechanical stresses on the switchgear components. These effects can be calculated in an FEM (Finite Element Method) simulation (Fig. 4).45678910Protective measures against direct contact, i. e. protection in the form of covering, obstruction or clearance and appropriately positioned protective devices and minimum heights. Protective measures against indirect touching by means of relevant grounding measures in accordance with DIN VDE 0141. Protective measures during work on equipment, i.e. during installation must be planned such that thespecifications of DIN EN 50110 (VDE 0105) (e.g. 5 safety rules) are complied with s Protective measures during operation, e.g. use of switchgear interlock equipment s Protective measures against voltage surges and lightning strike s Protective measures against fire, water and, if applicable, noise insulation.2/4Siemens Power Engineering Guide Transmission and Distribution 4th EditionDesign of Air-Insulated Outdoor SubstationsWhen rated and short-circuit currents are high, aluminum tubes are increasinglyused to replace wire conductors for busbars and feeder lines. They can handle rated currents up to 8000 A and short-circuit currents up to 80 kA without difficulty. Not only the availability of land, but also the lie of the land, the accessibility and location of incoming and outgoing overhead lines together with the number of transformers and voltage levels considerably influence the switchgear design as well. A one or two-line arrangement, and possibly a U arrangement, maybe the proper solution. Each outdoor switchgear installation, especially for step-up substations in connection with power stations and large transformer substations in the extra-highvoltage transmission system, is therefore unique, depending on the local conditions. HV/MV transformer substations of the distribution system, with repeatedly used equipment and a scheme of one incoming and one outgoing line as well as two transformers together with medium-voltage switchgear and auxiliary equipment, are more subject to a standardized design from the individual power supply companies.Preferred designsThe multitude of conceivable designs include certain preferred versions, which are dependent on the type and arrangement of the busbar disconnectors: H arrangement The H arrangement (Fig. 5) is preferrably used in applications for feeding industrial consumers. Two overhead lines are connected with two transformers andinterlinked by a single-bus coupler. Thus each feeder of the switchgear can be maintained without disturbance of the other feeders. This arrangement assures a high availability. Special layouts for single busbars up to 145 kV with withdrawable circuit-breaker and modular switchbay arrangement Further to the H arrangement that is built in many variants, there are also designs with withdrawable circuit-breakers and modular switchbays for this voltage range. For detailed information see the following pages:123456Vertical displacement in m 0.6 0.8 1.0 1.2 1.4 T1 1.6 Q1 M 1.8 2.0 2.2 1.4 Holacement in m 1.0 0.6 0.2 0 0.2 0.6 1.0 1.4 Q0 F1 = T1Fig. 5: Module plan viewM M Q8 Q87 Q0M Q0 Q1 T5 T1 Q1 T5 T1 T1M M8 Q10 Q11 Q1 Q09 F1 = T110Fig. 4: FEM calculation of deflection of wire conductors in the event of short circuitSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/5Design of Air-Insulated Outdoor SubstationsWithdrawable circuit-breaker12General For 123/145 kV substations with single busbar system a suitable alternative is the withdrawable circuit-breaker. In this kind of switchgear busbar- andoutgoing disconnector become inapplicable (switchgear6300 17001700without disconnectors). The isolating distance is reached with the moving of thecircuit-breaker along the rails, similar to the well-known withdrawable-unit design technique of medium-voltage switchgear. In disconnected position busbar, circuit-breaker and outgoing circuit are separated from each other by a good visible isolating dis2500 250037600 2247 =T1 -F1 2530 7000 -Q11 -T1/ 1050 -Q12 -Q9 -T5 -Q0 -Q0 -T1 3100 625 7000 625 3100 2500 4500 14450 21450-Q11-Q1242530 70003000 6400567Fig. 6a: H arrangement with withdrawable circuit-breaker, plan view and sections89tance. An electromechanical motive unit ensures the uninterrupted constant moving motion to both end positions. The circuitbreaker can only be operated if one of the end positions has been reached. Movement with switched-on circuit-breakeris impossible. Incorrect movement, which would be equivalent to operating a disconnector under load, is interlocked. In the event of possible malfunction of theposition switch, or of interruptions to travel between disconnected position and operating position, the operation of the circuitbreaker is stopped. The spacerequired for the switchgear is reduced considerably. Due to the arrangement of the instrument transformers on the common steel frame a reduction in the requiredspace up to about 45% in comparison to the conventional switchgear section is achieved. Description A common steel frame forms the base for all components necessary for reliable operation. The withdrawable circuit-breaker contains: s Circuit-breaker type 3AP1F s Electromechanical motive unit s Measuring transformer for protection and measuring purposes s Local control cubicle All systems are preassembled as far as possible. Therefore the withdrawable CB can be installed quite easily and efficiently on site. The advantages at a glance s Complete system and therefore lower costs for coordination and adaptation. s A reduction in required space by about 45% compared with conventional switchbays s Clear wiring andcabling arrangement s Clear circuit state s Use as an indoor switchbay is also possible.Technical data10Nominal voltage [kV] Nominal current [A] Nominal short time current [kA]123 kV (145 kV) 1250 A (2000 A) 31.5 kA, 1s, (40 kA, 3s) 230/400 V AC 220 V DCAuxiliary supply/ motive unit [V] Control voltageFig. 6b: H arrangement with withdrawable circuit-breaker, ISO view Fig. 7: Technical data[V]2/6Siemens Power Engineering Guide Transmission and Distribution 4th EditionDesign of Air-Insulated Outdoor SubstationsModular switchbayGeneral As an alternative to conventional substations an air-insulated modular switchbay can often be used for common layouts. In this case the functions of several HV devices are combined with each other. This makes it possible to offer astandardized module. Appropriate conventional air-insulated switchbays consist of separately mounted HV devices (for example circuit-breaker, disconnector, earthing switches, transformers), which are connected to each other by conductors/tubes. Every device needs its own foundations, steel structures, earthing connections, primary and secondary terminals (secondary cable routes etc.).3000Description A common steel frame forms the base for all components necessary fora reliable operation. The modul contains: s Circuit-breaker type 3AP1F s Motoroperated disconnecting device s Current transformer for protection and measuringpurposes s Local control cubicle All systems are preassembled as far as possible. Therefore the module can be installed quite easily and efficiently on site.The advantages at a glance s Complete system and therefore lower costs for coordination and adaptation. s Thanks to the integrated control cubicle, upgrading ofthe control room is scarecely necessary. s A modular switchbay can be insertedvery quickly in case of total breakdown or for temporary use during reconstruction. s A reduction in required space by about 50% compared with conventional switchbays is achieved by virtue of the compact and tested design of the module (Fig. 8). s The application as an indoor switchbay is possible.1234Technical data2000 2000Nominal voltage Nominal current8000123 kV (145 kV) 1250 A (2000 A) 31.5 kA, 1s, (40 kA, 3s) 230/400 V AC 220 V DC5Nominal short current Auxiliary supply-Q8 -Q0-Q1 -T1 -Q10/-Q11 -T1 -Q1 -Q0 -F1 -T5 3000 4500 7500 4500 3000 11500 4000=T1Control voltageFig. 9: Technical data678000 95008190003000A A99500 8000107500 19000Fig. 8: Plan view and side view of H arrangement with modular switchbays11500Siemens Power Engineering Guide Transmission and Distribution 4th Edition2/7Design of Air-Insulated Outdoor Substations1In-line longitudinal layout, with rotary disconnectors, preferable up to 170 kVThe busbar disconnectors are lined up one behind the other and parallel to the longitudinal axis of the busbar. It is preferable to have either wire-type or tubular busbars located at the top of the feeder conductors. Where tubular busbarsare used, gantries are required for the outgoing overhead lines only. The systemdesign requires only two conductor levels and is therefore clear. If, in the case of duplicate busbars, the second busbar is arranged in U form relative to thefirst busbar, it is possible to arrange feeders going out on both sides of thebusbar without a third conductor level (Fig. 10).Section A-A R1 S1 T1 T2 S2 R2Dimensions in mm 2500 80002205008400 4830019400 Top view6500 End bay 4500 Normal 9000 bay A A 900034Central tower layout with rotary disconnectors, normally only for 245 kV The busbar disconnectors are arranged side by side and parallel to the longitudinal axis of the feeder. Wire-type busbars located at the top are commonly used; tubularbusbars are also conceivable. This arrangement enables the conductors to be easliy jumpered over the circuit-breakers and the bay width to be made smaller thanthat of in-line designs. With three conductor levels the system is relatively clear, but the cost of the gantries is high (Fig. 11).Fig. 10: Substation with rotary disconnector, in-line design5Dimensions in mm 3000 12500 9000 7000 18000 17000 1700067160008Fig.11: Central tower designDiagonal layout with pantograph disconnectors, preferable up to 245 kVSection Bus system 1330010000 8000 28000 48000910The pantograph disconnectors are placed diagonally to the axis of the busbars and feeder. This results in a very clear, spacesaving arrangement. Wire and tubular conductors are customary. The busbars can be located above or below the feederconductors (Fig. 12).Dimensions in mm Bypass bus1000010400 Top view 5000 18000 4000 4000 5000Fig. 12: Busbar area with pantograph disconnector of diagonal design, rated voltage 420 kV2/8Siemens Power Engineering Guide Transmission and Distribution 4th EditionDesign of Air-Insulated Outdoor Substations1 1/2 circuit-breaker layout, preferable up to 245 kV The 1 1/2 circuit-breakerarrangement assures high supply reliability; however, expenditure for equipmentis high as well. The busbar disconnectors are of the pantograph, rotary and vertical-break type. Vertical-break disconnectors are preferred for the feeders. Thebusbars located at the top can be of wire or tubular type. Of advantage are theequipment connections, which are very short and enable (even in the case of multiple conductors) high short-circuit currents to be mastered. Two arrangements are customary: s External busbar, feeders in line with three conductor levels s Internal busbar, feeders in H arrangement with two conductor levels (Fig. 13).Planning principles 1For air-insulated outdoor substations of open design, the following planning principles must be taken into account: s High reliability Reliable mastering of normal and exceptional stresses Protection against surges and lightning strikes Protection against surges directly on the equipment concerned (e.g. transformer, HVcable)s Good clarity and accessibility23Dimensions in mm 4000 Clear conductor routing with few conductor levels Free accessibility to all areas (no equipment located at inaccessible depth) Adequate protective clearances for installation, maintenance and transportation work Adequately dimensioned transport routess Positive incorporation into surroundings451750085004800029000 As few overhead conductors as possible Tubular instead of wire-type busbars Unobtrusive steel structures Minimal noise and disturbance levels EMC grounding system618000for modern control and protections Fire precautions and environmental7Fig.13 : 1 1/2 Circuit-breaker designprotection Adherence to fire protection specifications and use of flame-retardant and nonflammable materials Use of environmentally compatible technology and products For further information please contact: Fax: ++ 49 - 9131- 73 18 58 e-mail: Gerda.Friedel@erls04.siemens.de8910Siemens Power Engineering Guide Transmission and Distribution 4th Edition2/9Circuit-Breakers for 72 kV up to 800 kVGeneral 1Circuit-breaker for air-insulated switchgearCircuit-breakers are the main module of both AIS and GIS switchgear. They have to meet high requirements in terms of: s Reliable opening and closing s Consistent quenching performance with rated and short-circuit currents even after many switching operations s High-performance, reliable maintenancefree operating mechanisms. Technology reflecting the latest state of the art and years of operating experience are put to use in constant further development and optimization of Siemens circuitbreakers. This makes Siemens circuitbreakers able to meet all the demands placed on high-voltage switchgear. The comprehensive quality system, ISO 9001 certified, covers development, manufacture, sales, installation and aftersales service. Test laboratories are accredited to EN 45001 and PEHLA/STL.2345Main construction elements 6Each circuit-breaker bay for gas-insulated switchgear includes the full complement of isolator switches, grounding switches (regular or proven), instrument transformers, control and protection equipment, interlocking and monitoring facilities commonly used for this type of installation (See chapter GIS, page 2/30 and following). Circuit-breakers for air-insulated switchgear are individual components and are assembled together with all individual electrical and mechanical components of an AIS installation on site. All Siemens circuit-breaker types, whether air or gas-insulated, are made up of the same range of components, i.e.: s Interrupter unit s Operating mechanism s Sealing system s Operating rod s Control elements.Control elementsOperating mechanismInterrupter unit78910Circuit-breaker in SF6-insulated switchgearFig. 14: Circuit-breaker parts2/10Siemens Power Engineering Guide Transmission and Distribution 4th EditionCircuit-Breakers for 72 kV up to 800 kVInterrupter unit two arc-quenching principlesThe Siemens product range includes highvoltage circuit-breakers with self-compression interrupter chambers and twin-nozzle interrupter chambers for optimum switching performance under every operating condition for every voltage level. Selfcompression breakers 3AP high-voltage circuit-breakers for the lower voltage range ensure optimum use of the thermal energy of the arc in the contact tube. Thisis achieved by the selfcompression switching unit. Siemens patented this arc-quenching principle in 1973. Since then, we have continued to develop the technology of the selfcompression interrupter chamber. One of the technical innovationsis that the arc energy is being increasingly used to quench the arc. In short-circuit breaking operations the actuating energy required is reduced to that needed for mechanical contact movement. That means the operating energy is truly minimized. The result is that the selfcompression interrupter chamber allows the useof a compact stored-energy spring mechanism with unrestrictedly high dependability. Twin-nozzle breakers On the 3AQ and 3AT switching devices, a contact systemwith graphite twin-nozzles ensures consistent arc-quenching behavior and constant electric strength, irrespective of pre-stressing, i.e. the number of breaks and the switched current. The graphite twin-nozzles are resistant to burning andthus have a very long service life. As a consequence, the interrupter unit of the twin-nozzle breaker is particularly powerful. Moreover, this type of interrupter chamber offers other essential advantages. Generally, twin-nozzle interrupterchambers operate with low overpressures during arcquenching. Minimal actuatingenergy is adequate in this operating system as well. The resulting arc plasma has a comparatively low conductivity, and the switching capacity is additionally favourably influenced as a result.The twin-nozzle system has also proven itself in special applications. Its specific properties support switching without restriking of small inductive and capacitive currents. By virtue of its high arc resistance, the twin-nozzle system isparticularly suitable for breaking certain types of short circuit (e.g. short circuits close to generator terminals) on account of its high arc resistance.Specific use of the electrohydraulic mechanism The actuating energy required forthe 3AQ and 3AT high-voltage circuit-breakers at higher voltage levels is provided by proven electrohydraulic mechanisms. The interrupter chambers of these switching devices are based on the graphite twin-nozzle system. Advantages of the electrohydraulic mechanism at a glance:s Electrohydraulic mechanisms provide the12Operating mechanism two principles for all specific requirementsThe operating mechanism is a central module of the high-voltage circuit-breakers. Two different mechanism types are available for Siemens circuit-breakers: s Stored-energy spring actuated mechanism, s Electrohydraulic mechanism, depending on the area of application and voltage level, thus every time ensuring the best system of actuation. The advantages are trouble-free, economical and reliable circuit-breaker operation for all specific requirements. Specific use of the stored-energy spring mechanism The actuation concept of the 3AP high-voltage circuit-breaker is based on the storedenergy spring principle. The use of such an operating mechanism in the lower voltage range became appropriate as a result of development of a self-compression interrupter chamber that requires only minimal actuation energy. Advantages of the stored-energy spring mechanism at a glance:s The stored-energy spring mechanism of3high actuating energy that makes it possible to have reliable control even oververy high switching capacities and to be in full command of very high loads in the shortest switching time. s The switch positions are held safely even in the event of an auxiliary power failure. s A number of autoreclosing operations are possible without the need for recharging. s Energy reserves can be reliably controlled at any time. s Electrohydraulic mechanisms are maintenance-free, economical and have a long service life. s They satisfy the most stringent requirements regarding environmental safety. This has been proven by electrohydraulic mechanisms in Siemens high-voltage circuit-breakers over many years of service.45678fers the highest degree of operational safety. It is of simple and sturdy design with few moving parts. Due to the self-compression principle of the interrupterchamber, only low actuating forces are required. s Stored-energy spring mechanisms are readily available and have a long service life: Minimal stressing of thelatch mechanisms and rolling-contact bearings in the operating mechanism ensurereliable and wear-free transmission of forces. s Stored-energy spring mechanisms are maintenance-free: the spring charging gear is fitted with wear-free spur gears, enabling load-free decoupling.910Siemens Power Engineering Guide Transmission and Distribution 4th Edition2/11Circuit-Breakers for 72 kV up to 245 kV1Siemens circuit-breakers for the lower voltage levels 72 kV up to 245 kV, whether for air-insulated or gas-insulated switchgear, are equipped with self-compression switching units and spring-stored energy operating mechanisms.Breaking operating currents During the opening process, the main contact (4) opens first and the current commutates on the still closed arcing contact. If thiscontact is subsequently opened, an arc is drawn between the contacts (5). At thesame time, the contact cylinder (6) moves into the base (7) and compresses thequenching gas there. The gas then flows in the reverse direction through the contact cylinder (6) towards the arcing contact (5) and quenches the arc there. Breaking fault currents In the event of high short-circuit currents, the quenchinggas on the arcing contact is heated substantially by the energy of the arc. Thisleads to a rise in pressure in the contact cylinder. In this case the energy for creation of the required quenching pressure does not have to be produced by the operating mechanism. Subsequently, the fixed arcing contact releases the outflow through the nozzle (3). The gas flows out of the contact cylinder back into the nozzle and quenches the arc.Major features:s s s sSelf-compression interrupter chamber Use of the thermal energy of the arc Minimized energy consumption High reliability for a long time2The interrupter unitSelf-compression system3The current path The current path is formed by the terminal plates (1) and (8),the contact support (2), the base (7) and the moving contact cylinder (6). In closed state the operating current flows through the main contact (4). An arcing contact (5) acts parallel to this.45Closed position61 2 3 4 5Opening Main contact openOpening Arcing contact openOpen position71 2 3 4 5 686Terminal plate Contact support Nozzle Main contact Arc contact Contact cylinder7 Base 8 Terminal plate97108Fig. 15: The interrupter unit2/12Siemens Power Engineering Guide Transmission and Distribution 4th EditionCircuit-Breakers for 72 kV up to 245 kVThe operating mechanismSpring-stored energy type Siemens circuit-breakers for voltages up to 245 kV areequipped with spring-stored energy operating mechanisms. These drives are basedon the same principle that has been proving its worth in Siemens low and medium-voltage circuit-breakers for decades. The design is simple and robust with fewmoving parts and a vibration-isolated latch system of highest reliability. All components of the operating mechanism, the control and monitoring equipment and all terminal blocks are arranged compact and yet clear in one cabinet. Dependingon the design of the operating mechanism, the energy required for switching is provided by individual compression springs (i.e. one per pole) or by springs thatfunction jointly on a triple-pole basis. The principle of the operating mechanism with charging gear and latching is identical on all types. The differences between mechanism types are in the number, size and arrangement of the opening andclosing springs. Major features at a glances Uncomplicated, robust construction11 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1823 94 5 6 71011 12 13 14 15 16 17Corner gears Coupling linkage Operating rod Closing release Cam plate Charging shaft Closing spring connecting rod Closing spring Hand-wound mechanism Chargingmechanism Roller level Closing damper Operating shaft Opening damper Opening release Opening spring connecting rod Mechanism housing Opening spring123456with few moving partss Maintenance-free s Vibration-isolated latches s Load-free uncoupling of charging7mechanisms Ease of access s 10,000 operating cycles8 188Fig. 16910Fig. 17: Combined operating mechanism and monitoring cabinetSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/13Circuit-Breakers for 245 kV up to 800 kV1Siemens circuit-breakers for the higher voltage levels 245 kV up to 800 kV, whether for air-insulated or gas-insulated switchgear, are equipped with twin-nozzleinterrupter chambers and electrohydraulic operating mechanisms.Arc-quenching assembly The fixed tubes (2) are connected by the contact tube (3)when the breaker is closed. The contact tube (3) is rigidly coupled to the blast cylinder (4), the two together with a fixed annular piston (5) in between forming the moving part of the break chamber. The moving part is driven by an operating rod (8) to the effect that the SF6 pressure between the piston (5) and the blast cylinder (4) increases. When the contacts separate, the moving contact tube(3), which acts as a shutoff valve, releases the SF6. An arc is drawn between one nozzle (6) and the contact tube (3). It is driven in a matter of millisecondsbetween the nozzles (6) by the gas jet and its own electrodynamic forces and issafely extinguished. The blast cylinder (4) encloses the arcquenching arrangement like a pressure chamber. The compressed SF6 flows radially into the break bythe shortest route and is discharged axially through the nozzles (6). After arcextinction, the contact tube (3) moves into the open position. In the final position, handling of test voltages in accordance with IEC 60000 and ANSI is fully assured, even after a number of short-circuit switching operations.Major featuress Erosion-resistant graphite nozzles s Consistently high dielectric strength s Consistent quenching capability acrossthe entire performance ranges High number of short-circuit breaking2 The interrupter unit 3Twin-nozzle system Current path assembly The conducting path is made up of the terminal plates (1 and 7), the fixed tubes (2) and the spring-loaded contact fingers arranged in a ring in the moving contact tube (3).operationss High levels of availability s Long maintenance intervals.4567Breaker in closed position 1PrecompressionGas flow during arc quenchingBreaker in open position82 3 6 4 51 Upper terminalplate2 Fixed tubes 3 Moving contacttube Arc94 Blast cylinder 5 Blast piston 6 Arc-quenchingnozzles102 87 Lower terminalplate8 Operating rod7Fig. 18: The interrupter unit2/14Siemens Power Engineering Guide Transmission and Distribution 4th EditionCircuit-Breakers for 245 kV up to 800 kVThe operating mechanismElectrohydraulic type All hydraulically operated Siemens circuitbreakers have auniform operating mechanism concept. Identical operating mechanisms (modules) are used for single or triple-pole switching of outdoor circuitbreakers. The electrohydraulic operating mechanisms have proved their worth all over the world. Thepower reserves are ample, the switching speed is high and the storage capacitysubstantial. The working capacity is indicated by the permanent self-monitoringsystem. The force required to move the piston and piston rod is provided by differential oil pressure inside a sealed system. A hydraulic storage cylinder filled with compressed nitrogen provides the necessary energy. Electromagnetic valvescontrol the oil flow between the high and low-pressure side in the form of a closed circuit. Main features:s Plenty of operating energy s Long switching sequences s Reliable check of energy reserves ss Tripping:The hydraulic valve is changed over electromagnetically, thus relieving the larger piston surface of pressure and causing the piston to move onto the OFF position. The breaker is ready for instant operation because the smaller piston surface is under constant pressure. Two electrically separate tripping circuits are available for changing the valve over for tripping.123456s s s sat any time Switching positions are reliably maintained, even when the auxiliarysupply fails Excessive strong foundations Low-noise switching No oil leakage and consequently environmentally compatible Maintenance-free.Fig. 19: Operating unit of the Q range AIS circuit breakersFig. 20: Operating cylinder with valve block and magnetic releases7Description of functions Closing:Monitoring unit and hydraulic pump with motorPPPPOil tank Hydraulic storage cylinder N2M8The hydraulic valve is opened by electromagnetic means. Pressure from the hydraulic storage cylinder is thereby applied to the piston with two different surfaceareas. The breaker is closed via couplers and operating rods moved by the forcewhich acts on the larger surface of the piston. The operating mechanism is designed to ensure that, in the event of a pressure loss, the breaker remains in theparticular position.M9Operating cylinder Operating piston Main valve Auxiliary switch Pilot control ReleasesFig. 21: Schematic diagram of a Q-range operating mechanism10OnOffSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/15Live-Tank Circuit-Breakers for 72 kV up to 800 kV1Circuit-breakers for air-insulated switchgear Standard live-tank breakersThe construction All live-tank circuit-breakers are of the same general design,as shown in the illustrations. They consist of the following main components: 1)Interrupter unit 2) Closing resistor (if applicable) 3) Operating mechanism 4)Insulator column (AIS) 5) Operating rod 6) Breaker base 7) Control unit The uncomplicated design of the breakers and the use of many similar components, such asinterrupter units, operating rods and control cabinets, ensure high reliabilitybecause the experience of many breakers in service has been applied in improvement of the design. The twin nozzle interrupter unit for example has proven its reliability in more than 60,000 units all over the world. The control unit includes all necessary devices for circuit-breaker control and monitoring, such as: sPressure/SF6 density monitors s Gauges for SF6 and hydraulic pressure (if applicable) s Relays for alarms and lockout s Antipumping devices s Operation counters(upon request) s Local breaker control (upon request) s Anticondensation heaters. Transport, installation and commissioning are performed with expertise and efficiency. The tested circuit-breaker is shipped in the form of a small number ofcompact units. If desired, Siemens can provide appropriately qualified personnel for installation and commissioning.234Fig. 22: 145 kV circuit-breaker 3AP1FG with triple-pole spring stored-energy operating mechanismFig. 23: 800 kV circuit-breaker 3AT55678910Fig. 24: 245 kV circuit-breaker 3AQ22/16Siemens Power Engineering Guide Transmission and Distribution 4th EditionLive-Tank Circuit-Breakers for 72 kV up to 800 kV11 2 7 3 5 612825 1 2 3 4Interrupter unit Closing resistor Valve unit Electrohydraulic operating mechanism 5 Insulator columns 6 Breaker base 7 Control unit39 13 12 10 11 443 4 7 6Fig. 25: Type 3AT4/551 2 3 4 5 6 7 8 9 10 11 12 13Interrupter unit Arc-quenching nozzles Moving contact Filter Blast piston Blastcylinder Bell-crank mechanism Insulator column Operating rod Hydraulic operatingmechanism ON/OFF indicator Oil tank Control unit6718Fig. 27: Type 3AQ2293 5 4 1 2 3 4Interrupter unit10Post insulator Circuit-breaker base Operating mechanism and control cubicle5 PillarFig. 26: Type 3AP1FGSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/17Live-Tank Circuit-Breakers for 72 kV up to 800 kV1Technical data234Type Rated voltage Number of interrupter units per pole Rated power-frequency withstand voltage 1 min. Rated lightning impulse withstand voltage 1.2 / 50 s Ratedswitching impulse withstand voltage Rated current up to Rated short-time current (3 s) up to Rated peak withstand current up to Rated short-circuit-breaking current up to Rated short-circuit making current up to Rated duty cycle Break timeFrequency Operating mechanism type Control voltage Motor voltage Design data ofthe basic version: Clearance Phase/earth in air across the contact gap Minimumcreepage Phase/earth distance across the contact gap Dimensions Height Width Depth Distance between pole centers Weight of circuit-breaker Inspection afterFig. 28a3AP1/3AQ1 [kV] [kV] [kV] [kV] [A] [kA] [kA] [kA] [kA]72.5 1 140 325 4000 40 108 40 108 123 1 230 550 4000 40 108 40 108 145 1 275 650 4000 40 108 40 108 170 1 325 750 4000 40/50 135 40/50 135 245/300 1 460 1050 /850 4000 50 135 50 135 or3AP2/3AQ2362 2 520 1175 950 4000 63 170 63 170 CO - 15 s - CO 3 50/60 3 50/60 420 2 610 1425 1050 4000 63 170 63 170567O - 0.3 s - CO - 3 min - CO8[cycles] [Hz] [V, DC] [V, DC] [V, DC] [mm] [mm] [mm] [mm] [mm] [mm] [mm] [mm] [kg]333 50/603 50/603 50/6050/60 50/60Spring-stored energy mechanism/Electrohydraulic mechanism 60250 60250 120240, 50/60Hz 700 1200 2248 3625 2750 3200 660 1350 1350 1250 1200 3625 3625 3300 3900 6601700 1500 1250 1200 3625 3625 3300 3900 660 1700 1500 1500 1400 4250 4250 40304200 660 1850 1600 2200 1900/2200 6150/7626 6125/7500 5220/5520 6600/7000 800 2800/3000 3000 25 years 2750 2700 7875 9050 4150 8800 3500 3800 4700 3400 3200 10375 10500 4800 9400 4100 4100 50009102/18Siemens Power Engineering Guide Transmission and Distribution 4th EditionLive-Tank Circuit-Breakers for 72 kV up to 800 kV1233AT2/3AT3*245 2 460 1050 4000 80 216 80 216 300 2 460 1050 8500 1175 950 4000 63 170 63 170 420 2 610 1425 1050 4000550 1175 4000 63 170 63 170 or 362 4 520 1175 950 4000CO 2 50/60 2 50/60 420 4 610 1425 1050 4000 80 200 804000 63 170 63 170 362 2 5263 170 63 170 550 2 800 180 200 80 200 CO - 15 s 2003AT4/3AT5*550 4 800 1550 1175 4000 63 160 63 160 800 4 1150 2100 14254564000 63 160 63 1607O - 0.3 s - CO - 3 min - CO 2 50/60 2 50/60 2 50/60 2 50/60 2 50/602 50/602 50/608Electrohydraulic mechanism 48250 48250 or 208/120500/289 50/60 Hz 2200 2000 6050 6070 4490 7340 4060 3000 5980 2200 2400 6050 8568 4490 8010 4025 3400 6430 2700 2700 7165 9360 6000 9300 4280 3900 9090 3300 3200 9075 11390 6000 10100 4280 43008600 3800 3800 13750 13750 6700 13690 5135 5100 12500 25 yearsFig. 28bSiemens Power Engineering Guide Transmission and Distribution 4th Edition * withclosing resistor92700 4000 7165 12140 4990 10600 6830 4350 14400 3300 4000 9075 12140 6000 114006830 4750 14700 3800 4800 10190 17136 6550 16600 7505 7200 19200 5000 6400 1386022780 8400 22200 9060 10000 23400102/19Dead-Tank Circuit-Breakers for 72 kV up to 245 kV1Circuit-breakers in dead-tank designFor certain substation designs, dead-tank circuit-breakers might be required instead of the standard live-tank breakers. For these purposes Siemens can offer the dead-tank circuit breaker types.2Main features at a glance 3Reliable opening and closings Proven contact and arc-quenchingsystem4s Consistent quenching performancewith rated and short-circuit currents even after many switching operations s Similar uncomplicated design for all voltages High-performance, reliable operatingmechanismss Easy-to-actuate spring operating5mechanismss Hydraulic operating mechanisms with6on-line monitoring Economys Perfect finish s Simplified, quick installation process Fig. 29a: SPS-2 circuit-breaker 72.5 kV7s Long maintenance intervals s High number of operating cycles s Long service lifeIndividual service8s Close proximity to the customer s Order specific documentation s Solutions tailored to specific problems s After-sales service available promptlyworldwide9The right qualificationss Expertise in all power supply matters s 30 years of experience with SF6-insulated circuit breakers10s A quality system certified to ISO 9001,covering development, manufacture, sales, installation and after-sales service sTest laboratories accredited to EN 45001 and PEHLA/STLFig. 29b: SPS-2 circuit-breaker 170 kV2/20Siemens Power Engineering Guide Transmission and Distribution 4th EditionDead-Tank Circuit-Breakers for 72 kV up to 245 kVSubtransmission breaker Type SPS-2 and 3AP1-DTType SPS-2 power circuit-breakers (Fig. 29a/b) are designed as general, definite-purpose breakers for use at maximum rated voltages of 72.5 and 245 kV. The construction The type SPS-2 breaker consists of three identical pole units mounted on a common support frame. The opening and closing force of the FA2/4 spring operating mechanism is transferred to the moving contacts of the interrupter througha system of connecting rods and a rotating seal at the side of each phase. Thetanks and the porcelain bushings are charged with SF6 gas at a nominal pressureof 6.0 bar. The SF6 serves as both insulation and arc-quenching medium. A control cabinet mounted at one end of the breaker houses the spring operating mechanism and breaker control components. Interrupters are located in the aluminum housings of each pole unit. The interrupters use the latest Siemens puffer arcquenching system. The spring operating mechanism is the same design as used with the Siemens 3AP breakers. This design has been in service for years, and has a well documented reliability record. Customers can specify up to four (in some cases, upto six) bushing-type current transformers (CT) per phase. These CTs, mounted externally on the aluminum housings, can be removed without disturbing the bushings.Operating mechanism The type FA2/4 mechanically and electrically trip-free spring mechanism is used on type SPS-2 breakers. The type FA2/4 closing and opening springs hold a charge for storing open-close-open operations A weatherproof controlcabinet has a large door, sealed with rubber gaskets, for easy access during inspection and maintenance. Condensation is prevented by units offering continuousinside/outside temperature differential and by ventilation.Included in the control cabinet are necessary auxiliary switches, cutoff switch,latch check switch, alarm switch and operation counter. The control relays andthree control knife switches (one each for the control, heater and motor) are mounted on a control panel. Terminal blocks on the side and rear of the housing are available for control and transformer wiring. For non US markets the control cabinet is also available similar to the 3AP cabinet (3AP1-DT).123Technical data4567Type Rated voltage Rated power-frequency withstand voltage Rated lighting impulse withstand voltage Rated switching impulse withstand voltage Rated nominal current up to [kV] [kV] [kV] [kV]38 80 200 48.3 105 250 4000 40SPS-2/3AP1-DT72.5 160 350 4000 40 121 260 550 4000 63 145 310 650 4000 63 169 365 750 4000 63242 425 900/105089/850 4000 63[A] 400040Rated breaking current up to [kA] Operating mechanism typeFig. 3010Spring-stored-energy mechanismSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/21Dead-Tank Circuit-Breakers for 550 kV1Circuit-breaker Type 3AT2/3-DTComposite insulators The 3AT2/3-DT is available with bushings made from composite insulators this has many practical advantages. The SIMOTEC composite insulatorsmanufactured by Siemens consist of a basic body made of epoxy resin reinforcedglass fibre tubes. The external tube surface is coated with vulcanized silicon.As is the case with porcelain insulators, the external shape of the insulator has a multished profile. Field grading is implemented by means of a specially shaped screening electrode in the lower part of the composite insulator. The bushings and the metal tank of the circuit-breaker surround a common gas volume. The composite insulator used on the bushing of the 3AT2/3-DT is a onepiece insulatingunit. Compared with conventional housings, composite insulators offer a wide range of advantages in terms of economy, efficiency and safety. Interrupter unit The 3AT2/3-DT pole consists of two breaking units in series impressive in the sheer simplicity of their design. The proven Siemens contact system with double graphite nozzles assures faultless operation, consistently high arc-quenching capacity and a long operating life, even at high switching frequencies. Thanks to constant further development, optimization and consistent quality assurance, Siemensarc-quencing systems meet all the requirements placed on modern high-voltage technology.Hydraulic drive The operating energy required for the 3AT2/3-DT interrupters isprovided by the hydraulic drive, which is manufactured inhouse by Siemens. The functional principle of the hydraulic drive constitutes a technically clear solution which offers certain fundamental advantages. Hydraulic drives provide high amounts of energy economically and reliably. In this way, even the most demandingswitching requirements can be mastered in short opening times. Siemens hydraulic drives are maintenancefree and have a particulary long operating life. They meet the strictest criteria for enviromental acceptability. In this respect, too,Siemens hydraulic drives have proven themselves throughout years of operation.For further information please contact: Fax: ++ 49 - 3 03 86 - 2 58 67234Technical data5678Type Rated voltage [kV] [kV] [kV] [kV] [A] [kA]3AT 2/3-DT550 860 1800 1300 4000 50/63 Electrohydraulic mechanism9Rated power-frequency withstand voltage Rated lighting impulse withstand voltage10Rated switching impulse withstand voltage Rated nominal current up to Rated breaking current up to Operating mechanism typeFig. 312/22Siemens Power Engineering Guide Transmission and Distribution 4th EditionDead-Tank Circuit-Breakers for 550 kV123456789Fig. 32: The 3AT2/3-DT circuit-breaker with SIMOTEC composite insulator bushings10Siemens Power Engineering Guide Transmission and Distribution 4th Edition2/23Surge ArrestersIntroduction 1The main task of an arrester is to protect equipment from the effects of overvoltages. During normal operation, it should have no negative effect on the power system. Moreover, the arrester must be able to withstand typical surges without incurring any damage. Nonlinear resistors with the following properties fulfill these requirements: s Low resistance during surges so that overvoltages are limited s High resistance during normal operation, so as to avoid negative effects onthe power system and s Sufficient energy absorption capability for stable operation With this kind of nonlinear resistor, there is only a small flow of currentwhen continuous operating voltage is being applied. When there are surges, however, excess energy can be quickly removed from the power system by a high discharge current.Nonlinear resistors Nonlinear resistors, comprising metal oxide (MO), have proved especially suitable for this. The nonlinearity of MO resistors is considerablyhigh. For this reason, MO arresters, as the arresters with MO resistors are known today, do not need series gaps. Siemens has many years of experience with arresters with the previous gapped SiC-arresters and the new gapless MO arresters in low-voltage systems, distribution systems and transmission systems. They are usually used for protecting transformers, generators, motors, capacitors, traction vehicles, cables and substations. There are special applications such as the protection of s Equipment in areas subject to earthquakes or heavy pollution s Surge-sensitive motors and dry-type transformers s Generators in power stations with arresters which posses a high degree of short-circuit current strength s Gasinsulated high-voltage metalenclosed switchgear (GIS) s Thyristors in HVDC transmission installations s Static compensators s Airport lighting systems s Electric smelting furnaces in the glass and metals industries s High-voltage cable sheaths s Test laboratory apparatus.234MO arresters are used in medium, high and extra-high-voltage power systems. Here, the very low protection level and the high energy absorption capability provided during switching surges are especially important. For high voltage levels, the simple construction of MO arresters is always an advantage. Another very important advantage of MO arresters is their high degree of reliability when used inareas with a problematic climate, for example in coastal and desert areas, or regions affected by heavy industrial air pollution. Furthermore, some special applications have become possible only with the introduction of MO arresters. One instance is the protection of capacitor banks in series reactive-power compensation equipment which requires extremly high energy absorption capabilities. Arresters with polymer housings Fig. 34 shows two Siemens MO arresters with different types of housing. In addition to what has been usual up to now the porcelain housing Siemens offers also the latest generation of high-voltage surge arresters with polymer housing.567Arrester voltage referred to continuous operating voltage /CRated voltage R Continuous operating voltage C829101 20 C 115 C 150 CFig. 34: Measurement of residual voltage on porcelain-housed (foreground) and polymer-housed (background) arresters010-410-310-210-1110102103104Current through arrester Ia [A]Fig. 33: Current/voltage characteristics of a non-linear MO arrester2/24Siemens Power Engineering Guide Transmission and Distribution 4th EditionSurge ArrestersFig. 35 shows the sectional view of such an arrester. The housing consists of afiberglass-reinforced plastic tube with insulating sheds made of silicon rubber.The advantages of this design which has the same pressure relief device as an arrester with porcelain housing are absolutely safe and reliable pressure reliefcharacteristics, high mechanical strength even after pressure relief and excellent pollution-resistant properties. The very good mechanical features mean that Siemens arresters with polymer housing (type 3EQ/R) can serve as post insulatorsas well. The pollution-resistant properties are the result of the water-repellent effect (hydrophobicity) of the silicon rubber, which even transfers its effects to pollution.The polymer-housed high-voltage arrester design chosen by Siemens and the highquality materials used by Siemens provide a whole series of advantages including long life and suitability for outdoor use, high mechanical stability and ease ofdisposal. Another important design shown in Fig. 36 are the gas-insulated metalenclosed surge arresters (GIS arresters) which have been made by Siemens for more then 25 years. There are two reasons why, when GIS arresters are used with gas-insulated switchgear, they usually offer a higher protective safety margin thanwhen outdoor-type arresters are used (see also IEC 60099-5, 1996-02, Section 4.3.2.2.): Firstly, they can be installed closer to the item to be protected so that traveling wave effects canbe limited more effectively. Secondly, compared with the outdoor type, inductance of the installation is lower (both that of the connecting conductors and thatof the arrester itself). This means that the protection offered by GIS arrestersis much better than by any other method, especially in the case of surges witha very steep rate of rise or high frequency, to which gas-insulated switchgear is exceptionally sensitive. Please find an overview of the complete range of Siemens arresters in Figs. 37 and 38, pages 26 and 27.123For further information please contact: Fax: ++ 49 - 3 03 86 -2 67 21 e-mail: arrester@siemens.de4SF6-SF6 bushing (SF6 -Oil bushing on request)5Flange with gas diverter nozzle SealAccess cover with pressure relief device and filterPressure relief diaphragm Compressing spring Metal oxide resistorsSpring contact Grading hood67Composite polymer housing FRP tube/silicon shedsMetal-oxide resistors Supporting rods Enclosure8910Fig. 36: Gas-insulated metal-enclosed arrester (GIS arrester)Fig. 35: Cross-section of a polymer-housed arresterSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/25Low-Voltage and Medium-Voltage Arresters and Limiters (230/400 V to 52 kV)Type1Low-voltage arresters and limiters 3EA2 3EF1 3EF2 3EF3 3EF4 3EF5Motors, dry-type transformers, airfield lighting systems, sheath voltage limiters, protection of converters for drivesMedium-voltage arresters 3EC3 3EE2 3EH2 3EG5 3EK5 3EK7 3EQ1-B2ApplicationsLowvoltage overhead line systems3DC systems (locomotives, overhead contact lines)4Generators, motors, melting furnaces, 6-arrester connections, power plantsDistribution systems metalenclosed gas-insulated switchgear with plug-in connection 45 52Distribution systems and mediumvoltage switchgearDistribution systems and mediumvoltage switchgearDistribution systems and mediumvoltage switchgearAC and DC locomotives, overhead contact lines5Nom. syst. [kV] voltage (max.) Highest [kV] voltage for equipment (max.)110 123 430 3630 3660 72.530 3625 306Maximum rated voltage Nominal discharge current[kV]1154455245754537 (AC) 4 (DC) 10[kA]5110101010101078Maximum [kJ/kV] energy absorbing capability (at thermal stability) Maximum longduration current impulse, 2 ms Maximum shortcircuit rating Housing material [A]3EF1/2 3EF3 3EF4 3EF50.8 9 12.5 810101.3353101 x 380 20 x 2503EF4 3EF51500 12001200120020030050030012009[kA]10Line disconnection Polymer40403001620202040PolymerPorcelainPorcelainMetalPorcelainPorcelainPolymerPolymerFig. 37: Low and medium-voltage arresters2/26Siemens Power Engineering Guide Transmission and Distribution 4th EditionHigh-Voltage Arresters (72.5 to 800 kV)Type 3EP1 ApplicationsMediumand highvoltage systems, outdoor installations3EP4Mediumand highvoltage systems, outdoor installations3EP2Highvoltage systems, outdoor installations3EP3Highvoltage systems, outdoor installations, HVDC, SC & SVC applications 7653EQ1Mediumand highvoltage systems, outdoor installationsMetal-oxide surge arresters 3EQ4 3EQ3 3EP2-K 3ER3Highvoltage systems, outdoor installations Highvoltage systems, outdoor installations, HVDC, SC & SVC applications 765 Highvoltage systems, metalenclosed gasinsulated switchgear 1503EP2-K3Highvoltage systems, metalenclosed gasinsulated switchgear 1503EP3-KHighvoltage systems, metalenclosed gasinsulated switchgear 500123Nom. syst. voltage (max.)[kV]60150500275500Highest [kV] voltage for equip. (max.) Maximum rated voltage Nominal discharge current Maximum line discharge class Maximum [kJ/kV] energy absorbing capability(at thermal stability) Maximum long duration current impulse, 2 ms Maximum shortcircuit rating [A] [kV]72.51705508003005508001701705504841474686122404686121801804445[kA]10 10 10/20 10/20 10 10/20 20 10/20 10/20 20235535544565812.520812.520101012.5750085015003900850150039001200120015008[kA]4065651005065809Minimum [kNm]2) breaking moment Maximum [MPSL] permissible service load Housingmaterial1)2.12)4.52)12.52)342)1063) 213) 723) Porcelain Porcelain2) Acc.Porcelain Porcelain3)Polymer1) Polymer1) Polymer1)MetalMetalMetalSilicon rubber shedsto DIN 48113Acc. to IEC TC 37 WG5 03.99; > 50% of this value are maintained after pressure reliefFig. 38: High-voltage arrestersSiemens Power Engineering Guide Transmission and Distribution 4th Edition2/27Gas-Insulated Switchgear for SubstationsIntroduction 1Common characteristic features of switchgear installation Because of its small size and outstanding compatibility with the environment, SF6 insulated switchgear(GIS) is gaining constantly on other types. Siemens has been a leader in this sector from the very start. The concept of SF6 - insulated metal-enclosed high-voltage switchgear has proved itself in more than 70,000 bay operating years in over 6,000 installations in all parts of the world. It offers the following outstanding advantages. Minimal space requirementsProtection of the environment The necessity to protect the environment often makes it dif cult to erect outdoor switchgear of conventional design, whereas buildings containing compact SF6-insulated switchgear can almost always be designed sothat they blend well with the surroundings. SF6-insulated metal-enclosed switchgear is, due to the modular system, very flexible and can meet all requirements of con guration given by network design and operating conditions.23Each circuit-breaker bay includes the full complement of disconnecting and grounding switches (regular or make-proof), instrument transformers, control and protection equipment, interlocking and monitoring facilities commonly used for thistype of installation (Fig. 39). Beside the conventional circuit-breaker bay, other arrangements can be supplied such as single-bus, ring cable with load-break switches and circuit-breakers, single-bus arrangement with bypass-bus, coupler and bay for triplicate bus. Combined circuitbreaker and load-break switch feeder,ring cable with load-break switches, etc. are furthermore available for the 145kV level.456The availability and price of land play an important part in selecting the typeof switchgear to be used. Siting problems arise in s Large towns s Industrial conurbations s Mountainous regions with narrow valleys s Underground power stations In cases such as these, SF6-insulated switchgear is replacing conventional switchgear because of its very small space requirements. Full protection against contact with live parts7The all-round metal enclosure affords maximum safety for personnel under all operating and