跟讀練習: How Do Substations Work? - 通過影片學習英語口語
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131 句
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When you plug in an electric device, it's easy not to even consider where the electricity actually comes from.
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The simple answer is a power generating station, also known as a power plant, usually someplace far away.
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But the reality is much more complicated than that.
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Generation is only the first of many steps our power takes on its nearly instantaneous journey from production to consumption.
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The behavior of electricity doesn't always follow our intuitions, which means the challenges associated with constructing,
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operating, and maintaining the power grid are often complicated and sometimes unexpected.
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Many of those challenges are overcome at a facility which, at first glance, often looks like a chaotic and dangerous mess of wires and equipment,
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but which actually serves a number of essential roles in our electrical grid.
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The substation.
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I'm Grady and this is Public Works, my video series on infrastructure and the human-made world around us.
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More on that later.
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As simple as it is to imagine, the power grid isn't just an interconnected series of wires to which all power producers and users collectively connect.
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In reality, the electricity normally makes its way through a series of discrete steps on the grid, normally divided into three parts.
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Generation, or production of electricity.
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Transmission, or moving that electricity from centralized plants to populated areas.
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And distribution, or delivering the electricity to every individual customer.
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If you consider the power grid a gigantic machine, and many do, substations are the linkages that connect the various components together.
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One of the cool parts about our electrical infrastructure is that most of it is out in the open, so anyone can have a look.
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I'm somewhat of an infrastructure tourist, a regular beholder of the constructed environment, and my goal is for you to be able to mentally untangle this maze of modern electrical engineering
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so that the next time you feast your eyes on a substation, you will be able to appreciate it as much as I do.
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Originally named for smaller power plants that were converted for other purposes,
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substation is now a general term for a facility that can serve a wide variety of critical roles on the power grid.
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Those roles depend on which parts of the electrical grid are being connected together.
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and the types, number, and reliability requirements of the eventual customers downstream.
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And the first and often simplest of these roles is switching.
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The general layout of a substation consists of some number of electric lines called conductors
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if you want to fit in with the electrical engineers coming into the facility.
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These high voltage conductors connect to a series of some
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or many pieces of equipment before heading out to their next step in the power grid.
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As a junction point in the grid, a substation often serves as the termination of many individual power lines.
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This creates redundancy, making sure that the substation stays energized even if one transmission line goes down.
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But it also creates complexity.
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The connections to these various devices are called buses, often rigid overhead conductors that run along the entire substation.
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The arrangement of the bus is a critical part of the design of any substation
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because it can have a major impact on the overall reliability.
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Like all equipment, substations occasionally have malfunctions or things that simply require regular maintenance.
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To avoid shutting down the entire substation, we need switches that can isolate equipment, transfer load, and control the flow of electricity along the bus.
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This may seem obvious, but turning on and off high voltage lines isn't as simple as flipping a light switch.
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At high voltages, even air can act like a conductor, which means even if you create a break in the line, electricity can continue flowing in a phenomenon known as an arc.
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Not only does arcing defeat the purpose of the switch, it is incredibly dangerous and damaging to equipment.
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So switching in a substation is a carefully controlled procedure with specially designed equipment to handle high voltages.
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Switches are often just called switchgear, in addition to the equipment that serves another important role in a substation, protection.
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I mentioned earlier that much of our electrical infrastructure is exposed and out in the open.
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That's nice for people like me who enjoy having a look, but it also means being vulnerable to an endless number of things that can go wrong.
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From lightning strikes to rogue tree limbs, wind storms to squirrels, grid operators contend with so many threats to their infrastructure on a day by day basis.
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When something causes a short circuit on the power grid, also called a fault, it can severely damage power lines and other equipment.
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Not only that, because of the overwhelming complexity of the power grid, faults can and do cascade in unexpected and sometimes uncontrollable ways,
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leaving huge populations without power for hours or days.
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Many of the ways we protect equipment from faults are handled at a substation.
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One of the most common types of electrical fault is a short circuit to ground.
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This type of fault creates a low resistance path for current to flow
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and leads to an overload of power lines and equipment.
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The simplest way to protect against this type of fault is with a fuse, a device that physically burns out at a certain current threshold.
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Fuses are dead simple and don't require much maintenance but they do have some disadvantages too.
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They are one time use, and they can't be used to interrupt current for other types of faults.
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On the other hand, circuit breakers are a class of devices that serve similar roles as fuses, but provide more sophistication for dealing with a wide variety of faults.
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Like disconnect switches, circuit breakers need to be carefully designed to interrupt huge voltages and currents without damage.
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As soon as contacts within a circuit breaker are moved apart from one another, an electrical arc forms.
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This arc needs to be extinguished as quickly as possible to prevent damage to the breaker or unsafe conditions for workers.
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Extinguishing the arc is accomplished by a material called dielectric that doesn't conduct electricity.
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For lower voltages, the circuit breakers can be located in a sealed container under vacuum to avoid electricity conducting in the air between the contacts.
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For higher voltage, breakers are often submerged in tanks filled with non-conductive oil or dense dielectric gas.
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These breakers give grid operators more control about how and when current gets interrupted.
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Not every fault is the same
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and sometimes operators even know about a disturbance ahead of time and can trigger breakers early to prevent cascading failures.
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Many faults are temporary, like lightning strikes or swaying tree branches.
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A special kind of circuit breaker, called a recloser, can interrupt current for a short period of time
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and re-energize the line to test if the fault has cleared.
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Reclosers usually trip and reclose a few times, depending on their programming, before deciding that a fault is permanent and locking out.
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If electricity demand on the grid gets so high that it can't be met by the utility, substations may also be used to shed load.
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Rolling blackouts are used to lower the total electrical demand to avoid bigger failures on the grid.
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One of the most important parts on the power grid is that different segments flow at different voltages.
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Voltage is a measure of electrical potential, somewhat equivalent to the pressure of a fluid in a pipe.
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At large power plants, electricity is produced at a somewhat low voltage of around 10 to 30 volts or kV.
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From there, the voltages increase much higher so that it can travel along transmission lines.
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Using a higher voltage reduces the losses along the way, making them more efficient, but also much more dangerous.
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This is why overhead transmission lines are so tall, to keep them out of the way of trees and human activities.
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But when transmission lines reach the populated areas which they serve, it's not feasible to keep them so high in the air.
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So prior to distribution, the voltage of the grid needs to be brought back down, using transformers located within a substation.
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A transformer is an extremely simple device that relies on the alternating current of the grid to function.
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It consists of two adjacent coils of wire.
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As the voltage in one coil changes, it creates a magnetic field.
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This field couples with the other coil, inducing a voltage.
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The incredible part of a transformer has to do with the number of loops in each coil.
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The induced voltage will be a function of the ratio of the loops.
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For example, if the transmission side of a transformer has 1000 loops, while the distribution side has 100, the voltage on the distribution side will be 10 times less.
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This simple but incredible fact makes it possible for us to step up
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or down voltage as necessary to balance the safety and efficiency along each part of the power grid.
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The simplicity of transformers is great in a lot of ways, but it also means it can be difficult to make fine adjustments to the power leaving the substation.
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Because of this, many substations include equipment for monitoring and controlling the power on the grid.
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Instrument transformers are small transformers used to measure the voltage or current on the grid or provide power to system monitoring devices.
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Depending on the varying transmission and distribution losses, the voltage on the grid can also swing outside an acceptable range.
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Regulators are devices with multiple taps that can make small adjustments up
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or down to the distribution voltage on feeder lines leaving the substation toward customers.
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If you look closely, you can sometimes see the regulator dial indicating the tap position.
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All that different equipment requires lots of maintenance.
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The final and most important role of a substation is that it'd be safe for electricians and linemen to inspect, repair, and replace equipment.
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Substations are usually the only locations where extra high voltage power lines get close to the ground, so safety is absolutely critical.
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The buswork running along the substation is protected from short circuit by large insulators to avoid arcs to ground.
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Even the connections into each piece of equipment are done through a device called a bushing, which maintains a safe distance between energized lines and the grounded metal housings.
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Some substations have large concrete walls to serve as fire barriers between equipment.
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All substations are built with a grid of grounding rods and conductors buried below the surface.
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In the event of a fault, the substation needs to be able to sink lots of current into the ground to trip the breakers as quickly as possible.
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The grounded grid also makes sure that the entire substation and all its equipment are kept at the same voltage level,
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called an equipotential, so that touching any piece of equipment doesn't create a flow of electricity through a person.
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Finally, substations are surrounded by large fences and warning signs to make absolutely sure that any wayward citizens know to stay out.
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In many ways the grid is a one size fits all system, a gigantic machine to which we all connect, spinning in perfect synchrony across, in some cases, an entire continent.
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On the other hand, our electricity needs, including when we need it, how much we need, and how reliably it should be delivered, vary widely.
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Power requirements are vastly different between a sensitive research facility and a suburban residential neighborhood, between a military base and a country club golf course,
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and between a steel mill and a bowling alley.
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Likewise every electrical substation is customized to meet the needs of the infrastructure it links together.
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As the grid gets smarter, as demand patterns change, and as we hopefully continue to replace fossil fuel generation with sources of renewable energy to curb global warming,
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managing our electrical infrastructure will only get more challenging.
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So substations will continue to play a critical role in controlling and protecting the power grid.
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本課的詞彙與口語要點
這節 C1 級別的口語課以影片“How Do Substations Work?”為素材。 影片中反覆出現的詞有：substation, grid, voltage, equipment, electricity。 這段影片共有 131 個句子、2268 個單詞可供跟讀。 講話部分時長為 12:22。 說話人語速較快，每分鐘約 183 個詞，會出現較多連讀和弱讀。 只有 76% 的單詞屬於英語最常用的 3,000 詞，詞彙難度較高。
影片中的重點詞彙
影片中最難的 15 個單詞，附發音和釋義：
| 單詞 | 發音 | 釋義 |
|---|---|---|
| substation 名詞 | /sʌbˈsteɪʃən/ | 變電站 /變電站, 變電所 /變電所 |
| voltage 名詞 | /ˈvəʊltɪd͡ʒ/ | 電壓 /電壓 |
| transformer 名詞 | /tɹænsˈfoɹməɹ/ | 變壓器 /變壓器 |
| conductor 名詞 | /kənˈdʌktɚ/ | 指揮 /指揮, 指揮家 /指揮家 |
| interrupt 動詞 | /ˌɪntəˈɹʌpt/ | 打斷 /打斷, 插嘴 |
| fuse 名詞 | /fjuːz/ | 導火線 /導火線, 導火索 /導火索 |
| coil 名詞 | /kɔɪl/ | 螺線 /螺線, 螺旋 |
| dielectric 名詞 | /ˌdaɪ.ɪˈlɛk.tɹɪk/ | 電介質 /電介質, 電介質材料 /電介質材料 |
| gigantic 形容詞 | /d͡ʒaɪˈɡæntɪk/ | 巨大的 |
| adjustment 名詞 | /əˈd͡ʒʌst.mənt/ | 調整 /調整 |
| overhead 名詞 | /ˈəʊvəˌhɛd/ | 間接費用 /間接費用 |
| consist 名詞 | /kənˈsɪst/ | 編組 /編組 |
| construct 動詞 | /ˈkɑn.stɹʌkt/ | 建造, 建設 /建設 |
| complexity 名詞 | /kəmˈplɛk.sɪ.ti/ | 複雜性 /複雜性 |
| overwhelm 動詞 | /ˌoʊ.vɚˈwɛlm/ | 吞沒 /吞沒 |
影片中出現的短語動詞
| 單詞 | 釋義 |
|---|---|
| come up with 動詞 | 想出, 提出 |
| go down 動詞 | 下降, 下去 |
| go through 動詞 | 通過 /通過 |
影片中的語法
說話人最常用的結構，並附上影片中的原話：
| 結構 | 影片中的用法 |
|---|---|
| 被動語態 be + 過去分詞 — 強調發生了什麼，而不是誰做的 | are overcome · is sponsored · were converted |
| 現在完成時 have/has + 過去分詞 — 過去發生但與現在仍有關聯的事 | has cleared · have come |
| 定語從句 who / which + 從句 — 補充說明人或事物 | intuitions, which means · conductor, which means |
需要注意的發音
說話人用了 17 次縮略和弱讀形式，例如 don't, I'm, doesn't。請按聽到的簡短形式來說。
- “th” 音: bandwidth /ˈbændwɪdθ/, threshold /ˈθɹɛʃ(h)oʊld/
- “sh” 和 “zh” 音: substation /sʌbˈsteɪʃən/, termination /tɚmɪˈneɪʃən/, junction /ˈd͡ʒʌŋkʃən/, specially /ˈspɛʃəli/, threshold /ˈθɹɛʃ(h)oʊld/
- 長單詞——注意重音位置: dielectric /ˌdaɪ.ɪˈlɛk.tɹɪk/, regulator /ˈɹɛɡ.ju.leɪ.tɚ/, complexity /kəmˈplɛk.sɪ.ti/, termination /tɚmɪˈneɪʃən/, eventual /ɪˈvɛn.t͡ʃu.əl/
如何用這段影片練習
- 先完整聽一遍影片，不要開口，記下不認識的單詞。
- 先用 0.75 倍速逐句跟讀，熟練之後再回到正常速度。
- 錄下自己的聲音並與原聲對比，特別注意 substation, voltage, transformer 這類單詞。
什麼是跟讀法？
跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧，最初開發用於專業口譯員的培訓，並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大：您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同，跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性，語調，節奏，連讀，聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。