There are three possible causes for power flow limitations to a transmission line. These causes are thermal overload, voltage instability, and rotor angle instability. Thermal overload is caused by excessive current flow in a circuit causing overheating. Voltage instability is said to occur when the power required to maintain voltages at or above acceptable levels exceeds the available power. Rotor angle instability is a dynamic problem that may occur following faults, such as short circuit, in the transmission system. It may also occur tens of seconds after a fault due to poorly damped or undamped oscillatory response of the rotor motion.
Assignment 1. Match the words with their definitions.
1.transmission | a) an automatically operated electrical switch designed to protect an electrical circuit from damage |
2. circuit breaker | b) put too great a demand on (an electrical system) |
3. overload | c) passing or sending of something to a different place |
4. voltage | d) be greater in number or size than (a quantity, number, or other measurable thing) |
5. exceed | e) an electromotive force or potential difference expressed in volts |
Assignment 2. Mark the following statements as true (T) or false (F).
1. ______ The functions of the bulk transmission are to interconnect generators, to interconnect various areas of the network, and to transfer electrical energy.
2. ______ The electricity is transported from a railway station to a transmission subsystem.
3. _____ This portion of the system is called "bulk" because it delivers energy only to bulk loads.
4. ______ With adequate contact protection, the occurrence of undesired electric arcing causes significant degradation of the contacts.
5. ______ Voltage instability occurs when the power required to maintain voltages at or above acceptable levels exceeds the available power.
Assignment 3. Match heads and tails of the following sentences.
1.We may think of the transmission system | a) to interconnect the bulk power system with the distribution system. |
2.The function of the sub-transmission system is | b) to reduce the power loss which is dissipated on the way. |
3. Transformers are used to step up the voltage on the transmission line | c) as providing the medium of transportation for electric energy. |
4. Thermal overload is caused by | d) excessive current flow in a circuit causing overheating. |
5. Rotor angle instability is | e) a dynamic problem that may occur following faults in the transmission system. |
Assignment 4. Fill in the gaps using the given words.
areas | transmission | overhead | expensive | underground |
Transmission circuits may be built either ______(1) or overhead. Underground cables are used predominantly in urban ______(2) where acquisition of overhead rights of way are costly or not possible. They are also used for ______(3) under rivers, lakes and bays. _______(4) transmission is used otherwise because, for a given voltage level, overhead conductors are much less ______(5) than underground cables.
Вариант 4. Systems Engineers
Systems engineers design and coordinate large and complex projects known as systems. There are many kinds of systems, and although all are large, they vary in their complexity. A system has many parts that all interact extensively with one another. Often small systems can be part of larger systems. For example, a jet airliner can be a system. So, too, can all of the airplanes owned by one airline. All of the airplanes in a country make up a more extensive system. An even larger and more complex system includes all of a nation's transportation facilities. Systems engineers can work at various levels in the design and coordination of these systems.
Some other examples of systems are water and food distribution networks, experimental manned space flights, and military defense programs. Systems engineers also work on telephone systems, electric power systems, and sewage systems.
Systems engineers are responsible for coordinating the work of many engineers, each of whom is an expert in one part of a system. For instance, in the building of a jet airliner, electronics specialists are responsible for the guidance and control systems. Structural engineers design the body of the plane. Other experts decide on a power source for the jet. Still others design landing and takeoff methods. Each specialist concentrates on one area. The systems engineer coordinates all of these specialized efforts in order to produce the jet airliner.
Both government and private industry employ systems engineers to solve complex scientific and engineering problems, such as the development of new transportation systems, the design of rockets, or the improvement of communications systems. Systems engineers first gather all the necessary information about what is needed in a system. They select several possible ways of designing the system. Then they use a problem-solving method called systems analysis to break down the possible solutions into smaller parts.
Systems engineers use systems analysis to make a diagram of all the parts of a system. They use computers and such mathematical methods as algebra, probability theory, and statistics to convert their diagrams into mathematical equations. They develop theoretical models that will help them choose the best way to design a system. They can use a computer to test these models. For example, systems engineers may want to know whether a mass-transit system will meet future needs. They can feed information on population growth and other data into a computer. The computer will process the data and provide the engineers with information about the usefulness of the system.
Systems engineers can also test a possible system by using small-scale models or actual-size models of parts of a system. Once a system has been designed, further testing is done. Systems engineers generally stay with a system and coordinate all parts of it until it is working smoothly. They coordinate the work of many specialists during the development of a system. Sometimes systems engineers are called on to make improvements in existing systems.
Assignment 1. Match the words with their definitions.
1.system | a) the technology of using transistors and silicon chips, especially in devices such as radios, televisions, and computers. |
2.electronics | b) act in such a way as to have an effect on another; act reciprocally |
3.development | c) a set of things working together as parts of a mechanism or an interconnecting network; a complex whole |
4.interact | d) a mathematical statement saying that two amounts or values are the same |
5.equation | e) gradual growth or formation of something |
Assignment 2. Mark the following statements as true (T) or false (F).
1._____ A system has many parts that all interact extensively with one another.
2. _____ Systems engineers cannot work on telephone systems, electric power systems, and sewage systems.
3. ______ Both government and private industry employ systems engineers to solve complex scientific and engineering problems.
4. _____ Systems engineers use maps to make a diagram of all the parts of a system.
5. _____ Systems engineers rarely use computers and mathematical methods.
Assignment 3. Match heads and tails of the following sentences.
1. A larger and more complex system includes | a) at various levels in the design and coordination of these systems. |
2. Systems engineers are responsible | b) all of a nation's transportation facilities. |
3. Systems engineers first gather all the necessary information | c) about what is needed in a system. |
4. Systems engineers can work | d) further testing is done. |
5. Once a system has been designed, | e) for coordinating the work of many engineers. |
Assignment 4. Fill in the gaps using the given words.
develop | engineering | analysis | industries | systems engineers |
Systems engineers work for government agencies, computer companies, and many ______(1) that need to solve large and complex ______(2) problems. Large research projects sponsored by government, industry, or universities also employ teams of scientists and engineers, including ________(3). Sometimes these researchers ______(4) new theories that can be used as the basis for systems and analysis. Workers who use systems ______(5) to solve business problems rather than engineering problems are usually called systems analysts.
Вариант 5. The Internet
The Internet is a worldwide system of interconnected computer networks. When you connect your computer to the Internet via your Internet Service Provider (ISP) you become part of the ISPs network, which is connected to other networks that make up the Internet.
The World Wide Web (WWW or Web for short) is the part of the Internet that you can access using a web browser such as Internet Explorer or Firefox. It consists of a large number of web servers that host websites. Each website will normally consist of a number of web pages. A web page can contain text, images, video, animation and sound.
You can access a website or web page by typing its URL (Uniform Resource Locator) into the address bar of your browser. An example of a URL is http://www. bbc. co. uk. URLs will have the format ‘http’ and a domain (such as. uk). What goes in between is arbitrary, but often has the term “www”, e. g. http://www. bbc. co. uk, but it doesn’t have to, e. g. http://news. bbc. co. uk).
Https is the secure version of http. When you use https, any data you send or receive from the web server is encrypted. For example, when banking online, https is used to keep your account details safe.
Most sites have a page that links the user to the other main areas of the site. This is called the homepage.
Web pages are connected by hypertext links. When a link is clicked you will be taken to another page which could be on another server in any part of the world.
What is an intranet?
An intranet is a network that works like the Internet but is only available within a particular organisation, not to the public. An intranet may have web pages used to share company specific data within that company, such as internal telephone numbers or details of employee benefits.
Assignment 1. Match the words on the left with their definitions on the right.
1.interconnect | a) the means or opportunity to approach or enter a place |
2. access | b) if one thing is connected with another, there is a link or relationship between them. |
3. homepage | c) convert (information or data) into a cipher or code, esp. to prevent unauthorized access |
4. encrypt | d) a local or restricted communications network, especially a private network created using World Wide Web software |
5. intranet | e) is the main page of information about them, which often contains links to other pages about them. |
Assignment 2. Mark the following statements as true (T) or false (F)
1. ______ The Internet is a worldwide system of interconnected computer networks.
2. _______ When you connect your computer to the Internet via your Internet Service Provider (ISP) you become part of the ISPs network, which is not connected to other networks that make up the Internet.
3. ______ The World Wide Web (WWW or Web for short) is the part of the Internet that you can access using a web browser such as Opera and Mozilla Firefox.
4. ______ A web page can contain messages, poems, songs, and dictionaries.
5. ______ An intranet may have web pages used to share company specific data within that company, such as internal telephone numbers or details of employee benefits.
Assignment 3. Match heads and tails of the following sentences.
1. When you connect your computer to the Internet via your Internet Service Provider (ISP) | a) that you can access using a web browser such as Internet Explorer or Firefox. |
2. The World Wide Web (WWW or Web for short) is the part of the Internet | b) into the address bar of your browser. |
3. You can access a website or web page by typing its URL (Uniform Resource Locator) | c) you become part of the ISPs network, which is connected to other networks that make up the Internet |
4. When you use https, any data you send or receive from the web server is encrypted. For example, | d) such as internal telephone numbers or details of employee benefits. |
5. An intranet may have web pages used to share company specific data within that company | e) when banking online, https is used to keep your account details safe. |
Assignment 4. Fill in the gaps using the given words.
hypertext | worldwide | clicked | benefits | network |
The Internet is a ______(1) system of interconnected computer networks. When you connect your computer to the Internet via your Internet Service Provider (ISP) you become part of the ISPs _______(2), which is connected to other networks that make up the Internet. Web pages are connected by ______(3) links. When a link is ______(4) you will be taken to another page which could be on another server in any part of the world. An intranet may have web pages used to share company specific data within that company, such as internal telephone numbers or details of employee _______.
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