No. Birds do this all the time. What protects the bird is the fact that it doesn’t complete a circuit. It touches only one wire and nothing else. Although there is a substantial charge on the power line and some of that charge flows onto the bird when it lands, the charge move  ment is self-limiting. Once the bird has enough charge on it to have the same voltage as the power line, charge stops flowing. And even though the power line’s voltage rises and falls 60 times a second (or 50 times a second in some parts of the world), the overall charge movement at 10,000 volts just isn’t enough to bother the bird much. At 100,000 volts or more, the charge movement is uncomfortable enough to keep birds away, so you don’t see them landing on the extremely high-voltage transmission lines that travel across vast stretches of countryside.
   The story wouldn’t be the same if the bird made the mistake of spanning the gap from one wire to another. In that case, current could flow through the bird from one wire to the other and the bird would run the serious risk of becoming a flashbulb. Squirrels occasionally do this trick when they accidentally bridge a pair of wires. Some of the unexpected power flickers that occur in places where the power lines run overhead are caused by squirrels and occasionally birds vaporizing when they let current flow between power lines.

   A super-efficient system that has the potential to power, heat and cool homes across the UK is being developed at Newcastle University. It works by burning vegetable oil to power a generator and provide electricity for the home.

  The waste heat from this process is then used to provide heating and hot water and is also converted to cool a fridge.

  At each step, the waste heat that is produced from engine gases and cooling is used elsewhere to recover the maximum amount of energy from the system.

  In addition to this, the plant producing the fuel absorbs carbon whilst growing – resulting in near zero overall carbon emissions.

  Using these three forms of energy for home use is known as micro-trigeneration and this new design will take the concept of combined heat and power to the next level.

  Led by experts at the Sir Joseph Swan Institute for Energy Research at Newcastle University and drawing on expertise from across the UK and China, the design also includes a unique energy storage system.

  This allows home owners to store the extra electrical energy during ‘off-peak’ times – for example during the night – and efficiently releases it when it is needed most.

  Project leader Professor Tony Roskilly, of Newcastle University, explained: 'The supply of electricity, heating and cooling can be optimized by this one, efficient and sustainable system.

  'The combination of the generator and energy storage provides new ways to respond to changing energy demand in the home.'

  One of the potential oils to be used in the system comes from the seeds of the Croton Megalocarpus plant which grows in East Africa.

  Croton Megalocarpus oil brings with it the advantage of being able to grow on land that is not suitable for traditional farming or food production – providing a fuel without sacrificing land for food crops.

  Drawing on the modelling expertise of scientists at Ulster University, the team will build a full-scale prototype of the system.

  The energy storage system, being developed with Leeds University, will supply electricity and cooling - helping to ensure that the correct form of energy is available at the right time and that the engine operates at its optimum efficiency.

  Newcastle University’s Dr Yaodong Wang, said that this form of energy system for the hme would be highly efficient.

  'In the past, a significant barrier to the take-up of domestic scale micro-trigeneration systems has been the availability of the right energy at the right time,' he explained.

  'A household has varying energy demands depending on the time of day and the time of year.

  'By integrating new energy storage technology with the micro-trigeneration system we have the potential to overcome this barrier and make an impact on future domestic energy supply.'

  The £1.1m project is a joint UK-China research programme funded by the Engineering and Physical Sciences Research Council.

   On January 16, 2008, Xcel Energy announced the Smart Grid Consortium, of which Ventyx is a participant. The Consortium was established in December 2007, bringing together leading technologists, engineering firms, business leaders and IT experts to provide guidance as well as the products and services needed to bring Xcel Energy's vision of a Smart Grid City to life. Within this planned Smart Grid City, Xcel Energy will work in tandem with customers to determine when, where, and how they use their energy; resulting in lower bills, smarter energy management, better grid reliability, and a number of additional benefits.

   For more information, read the Xcel Energy press release and download and view the Xcel Energy Smart Grid City video—both of which are linked from this page.

   "For the first time, we have created proteins that conduct current extremely well but can also function as semiconductors in transistors, for example," says Mahiar Hamedi, who developed the technique together with Anna Herland and associates at the Division for Biomolecular and Organic Electronics. The technology is described in his doctoral dissertation.

  Last year Mahiar Hamedi made headlines with his invention of conductive textile fibers, which can be used to produce electronic cloth. Now he has scaled down that technology by a factor of about a thousand.

  These nano fibers are produced in ordinary test tubes. One component is amyloid fibers, long, stable protein fibers that occur naturally in living organisms and can cause, among other things, nerve disorders in humans and animals. The other component is a conjugated polymer (PEDOT-S), a plastic material that conducts current. When the two are mixed in water, the plastic attaches to the fibers and forms a conductive shell that is merely a handful of atoms thick.

  "The beauty of the self-assembly process is the ease under which PEDOT-S binds onto the amyloid fibrils directly in water without the need of any heat, and in a matter of a few minutes" Hamedi writes in his dissertation.

  By providing the fibers with charged outgrowths, it is possible to get the molecules themselves to form desired structures. This can be an inexpensive and effective way to create extremely tiny three-dimensional electronic circuits.

  Using their nano fibers as a channeling material, Mahiar Hamedi and his associates have constructed fully functional electrochemical transistors that work in the area of 0-0.5 volts.

  The dissertation also describes a method for creating nano patterns in conductive plastic. As organic material is beginning to be used in more and more advanced electronic circuits, there is a need to fit a huge number of components in a tiny area. The solution is to form the plastic in a mold with structures that are smaller than the wavelength of visible light - and therefore invisible!

  The dissertation Organic electronics on micro and nano fibers - from e-textiles to biomolecular nanoelectronics was publicly defended November 21, 2008. External examiner was George Malliaras, Cornell University, USA.

Want to get off the grid? the Electric grid that is. The QR5, from U.K.-based Quietrevolution, is a residential-scale wind turbine that generates enough electricity to power a standard U.S. home or a small office. It also looks like a piece of wind-powered sculpture. Unlike the shape of a conventional windmill propeller, it’s a Vertical-axis wind turbine.

  Beneath the skin is what Quietrevolution calls the world’s most efficient turbine for capturing air currents near buildings and other structures, with carbon-fiber blades shaped to grab gusty city winds without making much noise. But make sure your checkbook is fully charged: At $48,000, the QR5 costs twice as much as a traditional propeller-style unit that generates the same output. It’ll take 18 years to pay back your cost.

More ways to save

Computers: When not being actively used,turning off the computer is most economical,however; if the computer must be left on,turning off the monitor will cut the electricity consumption in half.

Aquariums: Keep aquariums covered to reduce the amount of moisture escaping.Elevated humidity levels in the home increase human discomfort.

Fireplace/Wood burnng stove: Check to make sure the damper is closed when the fireplace is not in use and keep wood stove doors closed.

In the kitchen: Do not use the oven or stove for heating the house.In general when cooking, using a microwaveoven instead will be less expensive.A dishwasher uses the same amount of electricity whether it is fully loaded or only contains a few items. Therefore, run full loads to save energy.Clean off freezer and refrigerator coils every six months. The dust that accumulates on the coils reduces efficiency. Also, a full freezer runs less, even if that means filling up water jugs and freezing them. Place these containers beneath food so that they’re not in the way.

Hot Water: Turn off the water heater if you will be away from home for two or more days. The thermostat should be set between 120 and 140 degrees. The lower this setting,the more energy it will save.

Around the house…

Lighting: Fluorescent lights are ideal for use in place of incandescent lights that are used frequently (more than about 3 hours a day). But, whether you use fluorescent lights or not, remember to turn off lights in unoccupied rooms.

Windows: Keep windows closed while heating the house. Also keep curtains closed during hours of extreme cold temperatures. If using venetian blinds, adjust them so that they reflect sun rays inward. Also, awning and jalousie windows should be closed as tight as possible to reduce air leaks. Open windows for natural ventilation only during mild weather.

Heating, Ventilation and Air Conditioning (HVAC): the largest electricity consumer in the house

Basic maintenance will go a long way to enhance the system’s efficiency and prolong the life of the HVAC unit. Heating units should be serviced annually. Clean filters monthly and replace when needed. A dirty filter restricts airflow and causes the unit to lose efficiency. Throughout the house, it’s important to keep all air supply registers to all rooms open and the return air pathways free from obstructions (furniture). Also, doors should be kept open to any room that has a supply air register but no return air vent within the room.Outside, it is wise to keep plants and other obstructions at least three feet away from the outside unit to prevent interference with air circulation.Temperature settings play a significant role in a home’s energy consumption. For each degree you set the heating thermostat below 68 degrees,you will see up to a 4% savings per degree.With this thought in mind, consider lowering the thermostat a few degrees and usingblankets during sleeping hours. Also, lowering the thermostat by five degrees when away from your home will generate a savings. While you can adjust the settings manually, you might also consider installing an electronic programmable thermostat to manage your temperature setting throughout the day and night.Many of these are suitable for the do-ityourselfer to easily install.

You will find it is less expensive to use a small heater to warm the temperature in one room of the house than it is to heat the whole house to the warmer temperature using the central system.

Fanning up more savings…

Fans: Bathroom exhaust fans play an important role in increasing the comfort of your home and should be run for about 20 minutes to effectively remove excess humidity from the area. To operate most efficiently, if there is an operational window in the bathroom, open the window slightly while the fan is running so that less heated air is pulled from the rest of the house. Do not run the fan longer than about 20 minutes and remember to close the window when you turn off the fan.When cooking, kitchen exhaust fans should likewise be run for about 20 minutes to effectively remove extra humidity added to the room.

   CHEYENNE, Wyo. – A new transmission line connecting the Front Range ofColorado with the wind-rich high plains of eastern Wyoming reached a significant milestone last week. The Wyoming-Colorado Intertie (WCI) Project announced today that a recent Open Season auction was a success, the winning bids have been accepted,and development of the project will continue. It is anticipated that much of the capacity of the transmission line will be committed for delivering Wyoming’s high-quality wind resources to benefit consumers in Colorado.

   “This is another important step in the development of additional transmission capacity so that Wyoming’s world-class wind power can be delivered to regional markets,”Wyoming Gov. Dave Freudenthal said. “This intertie strengthens an already solid working relationship between Wyoming and Colorado."The WCI Project is a public/private development partnership involving the Wyoming Infrastructure Authority (WIA), Trans-Elect Development Company LLC (Trans-Elect),and the Western Area Power Administration (Western), with Trans-Elect leading the development effort. The partnership was first announced September 27, 2005 and the Open Season auction culminates nearly three years of intensive development activity. As part of the Open Season process, the project sponsors had offered up to 850 megawatts of transmission capacity in a public auction. This has resulted in 585 megawatts of capacity purchase commitments from credit-worthy parties. GreenHunter Wind Company, LLC and Duke Energy Ohio, Inc, two wind developers with wind farms under development near Chugwater, Wyoming have secured capacity on the WCI project. The project sponsors are optimistic that the remaining 265 megawatts of Page 2 of 3

  capacity will be sold. The project sponsors expect to complete the siting, permitting, and construction of the line and begin operation by mid-2013.

  The new transmission line will be regulated by the Federal Energy Regulatory Commission (FERC) and the Open Season was designed to comply with federal regulatory policy. CRA International, Inc. was retained by the Project to design and implement the auction and to evaluate bids. The timing of the Open Season was also scheduled to be compatible with the Public Service Company of Colorado’s (PSCo’s) new resource plans, which include purchasing 500 megawatts of wind with deliveries beginning in 2013. PSCo plans to issue a bid for this wind energy later this year after the plan is approved by the Colorado Public Utilities Commission.

  Steve Waddington, WIA executive director, said “the WCI Open Season resulted in a 70 percent subscription to the line. I look forward to seeing more of Wyoming’s robust wind resource being added to Colorado’s resources and delivering benefits to nsumers along the Front Range. This has been a regional effort over several years to eliminate a long-standing transmission constraint between Colorado and Wyoming.”

  Robert Mitchell, CEO of Trans-Elect, stated that “Trans-Elect is pleased with the Open Season results which bring the WCI Project to this critical position. We are optimistic that commitments necessary for the project to proceed will be made soon.”

  Tim Meeks, Western Area Power Administration (Western) administrator, pointed out “Western and Trans-Elect have a proven track record for success in getting transmission built. In a public-private partnership with Pacific Gas & Electric Co., Western and Trans-Elect completed the $250 million, 84-mile transmission expansion project in California known as Path-15. The project was electrified in 2004, ahead of schedule and substantially below budget.”

  Trans-Elect, based in Bethesda, Maryland with regional offices in Denver and Chicago,formed in 1999 as the first independent transmission company in North America to pursue the evelopment of independently owned electric transmission with the twin objectives of increasing the reliability of the system and lowering costs to consumers.

  Trans-Elect is affiliated with The AES Corporation, a global power company.Created in 2004 by the State of Wyoming, the WIA's mission is to diversify and expand the state’s economy through improvements in Wyoming’s electric transmission Page 3 of 3

  infrastructure to facilitate the consumption of Wyoming energy. The Authority can participate in planning, financing, constructing, developing, acquiring, maintaining and operating electric transmission facilities and their supporting infrastructure. Legislati onprovided the WIA with bonding authority, and other powers, to promote transmission development in the state and throughout the region. It also provided the State Treasurer,with the approval of the State Loan and Investment Board, the authority to invest in WIA bonds.

  Part of the U.S. Department of Energy, Western annually markets and transmits more than 10,000 megawatts of power from hydroelectric power plants owned and operated by   the Bureau of Reclamation and the Army Corps of Engineers in 15 central and western states. Western is the operator of the transmission lines that currently link Colorado and Wyoming.

October 1, 2008

Taking charge of your household's electricity use makes good sense. You'll be getting more use out of every kilowatt-hour of electricity you're paying for, but did you know you'll be contributing to a more reliable electricity system too? And, by using electricity, or any energy, more efficiently, you'll also be doing your part to help protect the environment for everyone.

Energy-Saving Programs and Services

Where to start? Your electric company. America's electric companies have many ways to help you use electricity more efficiently. Electric companies always have expert advice.  And, often, they have a variety of low- or no-cost programs to help you make your home more energy efficient.

With average heating costs expected to increase by nearly 20 percent from last year, homeowners are looking for ways to put money back in their wallets while promoting a cleaner planet. To help address this challenge, a group of utilities, trade associations and nonprofits have joined together to launch the 2 Degree Pledge initiative.

Electric Company Success Stories

Since the early 1970s, electric company programs and services have helped residential, commercial, and industrial customers to use their electricity more wisely.  These efficiency efforts are making a difference.

Energy-Saving Tips and Products

A hundred years ago, electricity was a luxury. Today we cannot live without it. But even though we take electricity for granted, we need to remember to use it wisely. Using electricity wisely is good for the environment, saves money in your home and business, and keeps our nation's electricity supply more reliable.

You can take simple steps to make your home and business more energy efficient. The following links provide a number of low- or no-cost energy saving tips to help you become a wise energy consumer.

Federal and State Government Energy Assistance

    The federal government is another resource for saving energy. 

• The U.S. Department of Energy has a wide variety of information on using energy more wisely.
  
  

• The government also is offering tax credits for buying efficient appliances and for making homes and businesses more energy-efficient. 
  
  

• Your state also may have energy saving rebates and other incentives. 
  
  

• Finally, by partnering together, we can do even more. Be a part of a growing national effort to lower energy use by changing out one of your regular light bulbs for a compact fluorescent bulb. These have earned the government's ENERGY STAR® label for excellence in energy efficiency. Every ENERGY STAR®  qualified light bulb uses about two-thirds less energy than a standard bulb, lasts up to 10 times longer and can save about $30 or more in energy costs. 
   

  Confusing standards and conflicting opinions have plagued the field of grounding. One of the most important, but least understood considerations in designing and maintaining electrical systems is the grounding of all components. Low resistance earth grounding is essential for safety and protection of sensitive electronic equipment. It is the basis for any facility's power quality assurance program.

  Effective earth grounding is essential for grounded AC and DC electrical equipment and distribution systems. Effective grounding provides the level of safety required to protect personnel and equipment from shock and fire hazard. The understanding and evaluation of a facility ground system should be part of any power quality assurance program.

Some of the basic requirements of an effective ground system include:

• Limits voltage in a electrical distribution system to definite fixed values
• Limits voltage to within insulation ratings
• Provides a more stable system with a minimum of transient over voltage and electrical noise
• Provides a path to ground in fault conditions for quick isolation of equipment with operation of ground fault protection
• Provides grounding of all conductive enclosures that may be touched by personnel, thereby eliminating shock hazards
• Reduces static electricity that may be generated within facilities
• Provides protection from large electrical disturbances (such as lightning) by creating a low resistive path to earth

1 线路中励磁涌流问题

1.1 线路中励磁涌流对继电保护装置的影响

励磁涌流是由于变压器空载投运时，铁芯中的磁通不能突变，出现非周期分量磁通，使变压器铁芯饱和，励磁电流急剧增大而产生的。变压器励磁涌流最大值，可以达到变压器额定电流的6～8倍，并且跟变压器的容量大小有关，变压器容量越小，励磁涌流倍数越大。励磁涌流存在很大的非周期分量，并以一定时间系数衰减，衰减的时间常数同样与变压器容量大小有关，容量越大，时间常数越大，涌流存在时间越长。10 kV线路装有大量的配电变压器，在线路投入时，这些配电变压器是挂在线路上，在合闸瞬间，各变压器所产生的励磁涌流在线路上相互迭加、来回反射，产生了一个复杂的电磁暂态过程，在系统阻抗较小时，会出现较大的涌流，时间常数也较大。二段式电流保护中的电流速断保护，由于要兼顾灵敏度，动作电流值往往取得较小，特别在长线路或系统阻抗大时更明显。励磁涌流值可能会大于装置整定值，使保护误动。这种情况在线路变压器个数少、容量小以及系统阻抗大时并不突出，因此容易被忽视，但当线路变压器个数及容量增大后，就可能出现。贵阳市北供电局就曾经在变电所增容后出现10 kV线路由于涌流而无法正常投入的问题。

1.2 防止涌流引起误动的方法

励磁涌流一明显的特征，就是它含有大量的二次谐波，在主变压器主保护中就利用这个特性，来防止励磁涌流引起保护误动作，但如果用在10 kV线路保护，必须对保护装置进行改造，会大大增加装置的复杂性，因此实用性很差。励磁涌流的另一特征就是它的大小随时间而衰减，一开始涌流很大，一段时间后涌流衰减为零，流过保护装置的电流为线路负荷电流，利用涌流这个特点，在电流速断保护加入一短时间延时，就可以防止励磁涌流引起的误动作，这种方法最大优点是不用改造保护装置(或只作简单改造)，虽然会增加故障时间，但对于像10 kV这种对系统稳定运行影响较小之处还是适用。为了保证可靠地躲过励磁涌流，保护装置中加速回路同样要加入延时。通过几年的摸索，在10 kV线路电流速断保护及加速回路中加入了0.15～0.2 s的时限，就近几年运行来看，运行安全，并能很好的避免由于线路中励磁涌流造成保护装置误动作。

2 TA饱和问题

2.1 TA饱和对保护的影响

10 kV线路出口处短路电流一般都较小，特别是农网中的变电所，往往远离电源，系统阻抗较大。对于同一线路，出口处短路电流大小会随着系统规模及运行方式不同而不同。随着系统规模的不断扩大，10 kV系统短路电流会随着变大，可以达到TA一次额定电流的几百倍，系统中原有一些能正常运行的变比小的TA就可能饱和；另一方面，短路故障是一个暂态过程，短路电流中含大量非周期分量，又进一步加速TA饱和。在10 kV线路短路时，由于TA饱和，感应到二次侧的电流会很小或接近于零，使保护装置拒动，故障由母联断路器或主变压器后备保护切除，不但延长了故障时间，会使故障范围扩大，影响供电可靠性，而且严重威胁运行设备的安全。

2.2 避免TA饱和的方法

TA饱和，其实就是TA铁芯中磁通饱和，而磁通密度与感应电势成正比，因此，如果TA二次负载阻抗大，在同样电流情况下，二次回路感应电势就大，或在同样的负载阻抗下，二次电流越大，感应电势就越大，这两种情况都会使铁芯中磁通密度大，磁通密度大到一定值时，TA就饱和。TA严重饱和时，一次电流全部变成励磁电流，二次侧感应电流为零，流过电流继电器的电流为零，保护装置就会拒动。避免TA饱和主要从两个方面入手，一是在选择TA时，变比不能选得太小，要考虑线路短路时TA饱和问题，一般10 kV线路保护TA变比最好大于300/5。另一方面要尽量减少TA二次负载阻抗，尽量避免保护和计量共用TA，缩短TA二次电缆长度及加大二次电缆截面；对于综合自动化变电所，10 kV线路尽可能选用保护、测控合一的产品，并在控制屏上就地安装，这样能有效减小二次回路阻抗，防止TA饱和。

3 所用变压器保护

3.1 所用变压器保护存在的问题

所用变压器是一比较特殊的设备，容量较小但可靠性要求非常高，而且安装位置也很特殊，一般就接在10 kV母线上，其高压侧短路电流等于系统短路电流，可达十几千安，低压侧出口短路电流也较大。一直对所用变压器保护的可靠性重视不足，这将对所用变压器直至整个10 kV系统的安全运行造成很大的威胁。传统的所用变压器保护使用熔断器保护，其安全可靠性还是比较高，但随着系统短路容量的增大，以及综合自动化的要求提高，这种方式已逐渐满足不了要求。现在新建或改造的变电所，特别是综合自动化所，大多配置所用变压器开关柜，保护配置也跟10 kV线路相似，而往往忽视了保护用的TA饱和问题。由于所用变压器容量小，一次额定电流很小，保护计量共用TA，为确保计量的准确性，设计时TA很小，有的地方甚至选择10/5。这样一来，当所用变压器故障时，TA将严重饱和，感应到二次回路电流几乎为零，使所用变压器保护装置拒动。如果是高压侧故障，短路电流足以使母联保护或主变压器后备保护动作而断开故障，如果是低压侧故障，短路电流可能达不到母联保护或主变压器后备保护的启动值，使得故障无法及时切除，最终烧毁所用变压器，严重影响变压器的安全运行。

3.2 解决办法

解决所用变压器保护拒动问题，应从合理配置保护入手，其TA的选择要考虑所用变压器故障时饱和问题，同时，计量用的TA一定要跟保护用的TA分开，保护用的TA装在高压侧，以保证对所用变压器的保护，计量用TA装在所用变压器的低压侧，以提高计量精度。在定值整定方面，电流速断保护可按所用变压器低压出口短路进行整定，过负荷保护按所用变压器容量整定。

4 配电变压器保护

4.1 10 kV配电变压器保护存在的问题

10 kV配电变压器的保护配置主要有断路器、负荷开关或负荷开关加熔断器等。负荷开关投资省，但不能开断短路电流，很少采用；断路器技术性能好，但设备投资较高，使用复杂，广泛应用不现实；负荷开关加熔断器组合的保护配置方式，既可避免采用操作复杂、价格昂贵的断路器，弥补负荷开关不能开断短路电流的缺点，又可满足实际运行的需要，该配置可作为配电变压器的保护方式。但对于容量比较大的配电变压器，配备有瓦斯继电器，需要断路器可与瓦斯继电器相配合，才能对变压器进行有效的保护，必要时还应有零序保护，这些问题都是值得注意的问题。

4.2 解决办法

无论在10 kV环网供电单元，还是在终端用户高压配电单元中，采用负荷开关加高遮断容量后备式限流熔断器组合的保护配置，既可提供额定负荷电流，又可断开短路电流，并具备开合空载变压器的性能，能有效保护配电变压器。为此，推荐采用负荷开关加高遮断容量后备式限流熔断器组合的配置，作为配电变压器保护的保护方式。标准GB 14285《继电保护和安全自动装置技术规程》规定，选择配电变压器的保护设备时，当容量等于或大于800 kVA，应选用带继电保护装置的断路器。对于这个规定，可以理解为基于以下两方面的需要。

配电变压器容量达到800 kVA及以上时，过去大多使用油浸变压器，并配备有瓦斯继电器，使用断路器可与瓦斯继电器相配合，从而对变压器进行有效地保护。

对于装置容量大于800 kVA的用户，因种种原因引起单相接地故障导致零序保护动作，从而使断路器跳闸，分隔故障，不至于引起变电所的馈线断路器动作，影响其他用户的正常供电。 标准还明确规定，即使单台变压器未达到此容量，但如果用户的配电变压器的总容量达到800 kVA时，亦要符合此要求。

5 线路保护

5.1 10 kV配电线路保护中存在的问题

无论是城市内配网线路，还是农村配网线路，都以10 kV电压等级为主，但是10 kV配电线路结构特点是一致性差，如有的为用户专线，只带1～2个用户，类似于输电线路；有的呈放射状，几十台变压器T接于同一条线路的各个分支上；有的线路短到几百米，有的线路长到几十千米；有的线路由35 kV变电所出线，有的线路由110 kV变电所出线；有的线路上的配电变压器容量很小，最大不过100 kVA，有的线路上却有几千千伏安的变压器。

5.2 解决办法

10 kV配电线路的保护，一般采用电流速断、过电流及三相一次重合闸构成。特殊线路结构或特殊负荷线路保护，不能满足要求时，可考虑增加其它保护，如保护Ⅱ段、电压闭锁等。进行整定计算的过程中，应该考虑特殊情况和常规情况，并进行灵敏度校验。对于10 kV配电线路，保护装置的配置虽然较简单，但由于线路的复杂性和负荷的多变性，常规和特殊情况下，保护定值计算和保护装置的选型还是值得重视的。根据诸城电网保护配置情况及运行经验，利用规范的保护整定计算方法，各种情况均可计算，一般均可满足要求。