Тема: Electrical Engineering Materials (Электротехнические материалы)

·    Conductive materials include metals, electrolytes, superconductors, semiconductors, plasmas and some nonmetallic conductors such as graphite and conductive polymers.

·    Copper has a high conductivity. Annealed copper is the international standard to which all other electrical conductors are compared; the International Annealed Copper Standard conductivity is 58 MS/m. The main grade of copper used for electrical applications, such as building wire, motor windings, cables is electrolytic-tough pitch (ETP) copper .

·    If high conductivity copper must be welded or used in a reducing atmosphere, then oxygen-free high conductivity copper may be used. Because of its ease of by soldering or clamping connection, copper is still the most common choice for most light-gauge wires.

·     Silver is 6% more conductive than copper, but due to cost it is not practical in most cases. However, it is used in specialized equipment, such as satellites.

·     Aluminum wire is the most common metal in electric power transmission and distribution. Although only 61% of the conductivity of copper by cross-sectional area, its lower density makes it twice as conductive by mass. As aluminum is about one-third the cost of copper by weight, the economic advantages are considerable when large conductors are required.

·    The disadvantages of aluminum wiring lie in its mechanical and chemical properties. It readily forms an insulating oxide, making connections heat up.. Aluminum can slowly deform under load, and loosen connections.

·    Pure water is not an electrical conductor, even a small portion of ionic impurities, such as salt, can rapidly transform it into a conductor.

2. Найдите и запишите перевод терминов:

1.electrical applications               a) соединения             

2.Copper                                     b) обмотки двигателей

3.building wire                           c)бескислородная медь

4. motor windings                       D) размеры

5.Cables                                        e)специализированное оборудование

6.light-gauge wires                     f)электрооборудование

7.oxygen-free copper                 g)строительный провод

8.specialized equipment                          h)Медь

9.to heat up                                 i)нагревать

10.dimensions                               j)провода малого диаметра

3. Переведите словосочетания: