III. Ответьте на следующие вопросы, пользуясь информацией из текста
How is electricity usually transmitted?
How are redundant paths and lines provided?
The conductor material is nearly always an aluminum alloy, isn’t it?
What are improved conductor material and shapes regularly used for?
5. Why does most of the current flow close to the surface of the wire?
IV. Переведите на русский язык цепочки существительных. Обратите внимание, что последнее слово является опорным
Electric power transmission, the power plant, California electricity crisis, sub-transmission voltages, the conductor material, transmission circuits, railway electrification system, system stability considerations, underground power transmission, fuel resources.
V. Выразите свое согласие или несогласие, употребляя следующие слова и выражения. Подтвердите свою точку зрения фактами из текста
That’s exactly what I think, I agree entirely that …, Perhaps, but I don’t think that…, I can’t agree with you there, In my opinion… , Yes, that's true , That's right, I'm sure of that,I'm absolutely certain of that, I quite agree with you , I agree with you 100 percent, I couldn't agree with you more , That's so true , That's for sure, You're absolutely right, I have to side with you on this ,No doubt about it , I don't think so, I'm afraid I disagree , I totally disagree, I beg to differ, I'd say the exact opposite, Not neces-sarily, That's not always true, That's not always the case, No, I'm not so sure about that.
1. Electric power transmission is a process in the delivery of electricity to consumers.
2. Thinner wires would lead to a relatively small increase in capacity due to the skin effect.
3. Conductors are supplied by a few companies worldwide.
4. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line.
5. Transmission normally takes place at high voltage.
VI. Добавьте подходящие предлоги, где необходимо и составьте предложения со следующими инфинитивами
To be connected , to be based, to lead, , to determine, to be powered, to require , to depend
VII. Прокомментируйте ту часть текста, которая показалась вам наиболее интересной
VIII. Прочитайте текст без словаря
а) найдите определение вторичных элементов
Storage batteries are made up of rechargeable cells, often called secondary cells to distinguish them from primary cells. Secondary cells are made up of several different materials but all work on the principle of reversible chemical action between two dissimilar electrodes immersed in an active solution – electrolyte. Particular battery designs are much more complicated and have several plates in parallel , closely packed with insulating separators.
б)Найдите в тексте эквиваленты следующих словосочетаний
Чтобы отличить их от первичных элементов, на основе обратимого химического действия, изоляционные прокладки.
Homereading
Прочитайте текст по той же теме. Укажите общее и разное в их содержании
Bulk power transmission
Engineers design transmission networks to transport the energy as efficiently as feasible, while at the same time taking into account economic factors, network safety and redundancy. These networks use components such as power lines, cables, circuit breakers, switches and transformers.
A transmission substation decreases the voltage of electricity coming in allowing it to connect from long distance, high voltage transmission, to local, lower voltage, distribution. It also rerouts power to other transmission lines that serve local markets. The substation may also "reboost" power allowing it to travel greater distances from the power generation source along the high voltage transmission lines.This is the PacifiCorp Hale Substation, Orem, Utah.
Transmission efficiency is improved by increasing the voltage using a step-up transformer, which reduces the current in the conductors, while keeping the power transmitted nearly equal to the power input. The reduced current flowing through the conductor reduces the losses in the conductor and since, according to Joule's Law, the losses are proportional to the square of the current, halving the current makes the transmission loss one quarter the original value.
A transmission grid is a network of power stations, transmission circuits, and substations. Energy is usually transmitted within the grid with three-phase AC. DC systems require relatively costly conversion equipment which may be economically justified for particular projects. Single phase AC is used only for distribution to end users since it is not usable for large polyphase induction motors. In the 19th century two-phase transmission was used, but required either three wires with unequal currents or four wires. Higher order phase systems require more than three wires, but deliver marginal benefits.
The capital cost of electric power stations is so high, and electric demand is so variable, that it is often cheaper to import some portion of the variable load than to generate it locally. Because nearby loads are often correlated (hot weather in the Southwest portion of the United States might cause many people there to turn on their air conditioners), imported electricity must often come from far away. Because of the economics of load balancing, transmission grids now span across countries and even large portions of continents. The web of interconnections between power producers and consumers ensures that power can flow even if a few links are inoperative.
The unvarying (or slowly varying over many hours) portion of the electric demand is known as the "base load", and is generally served best by large facilities (and therefore efficient due to economies of scale) with low variable costs for fuel and operations, i.e. nuclear, coal, and renewables like hydro, solar, wind, ocean, etc.. Smaller- and higher-cost sources are then added as needed.
Long-distance transmission of electricity (thousands of miles) is cheap and efficient, with costs of US$ 0.005 to 0.02 per kilowatt-hour (compared to annual averaged large producer costs of US$ 0.01 to US$ 0.025 per kilowatt-hour, retail rates upwards of US$ 0.10 per kilowatt-hour, and multiples of retail for instantaneous suppliers at unpredicted highest demand moments). Thus distant suppliers can be cheaper than local sources (e.g. New York City buys a lot of electricity from Canada). Multiple local sources (even if more expensive and infrequently used) can make the transmission grid more fault tolerant to weather and other disasters that can disconnect distant suppliers.
Getting renewables connected into the long-distance transmission grid is critical for energy self-sufficiency and carbon reduction strategies for minimizing global warming impact. Hydro and wind sources can't be moved closer to high population cities, and solar costs are lowest in remote areas where local power needs are the least. Connection costs alone can determine whether any particular renewable alternative is economically sensible, e.g. costs can be prohibitive for redundant transmission lines up to distant mountain ridges where enormous quantities of economically valuable high speed winds blow reliably.
Lesson 8
Electric motors