文档介绍：Chapter 6
Electric Power Systems
Section 1 Introduction
Text
New Words and Expressions
Exercises
End
Translation of Negative Sentences
Section 1 Introduction
The modern society depends on the electricity supply more heavily than ever before. It can not be imagined what the world should be if the electricity supply were interrupted all over the world. Electric power systems (or electric energy systems), providing electricity to the modern society, have e ponents of the industrial world.
Section 1 Introduction
The plete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison – the historic Pearl Street Station in New York City which began operation in September 1882. This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system. Within a few years similar systems were in
Section 1 Introduction
operation in most large cities throughout the world. With the development of motors by Frank Sprague in 1884, motor loads were added to such systems. This was the beginning of what would develop into one of the largest industries in the world. In spite of the initial widespread use of DC systems, they were pletely superseded by AC systems. By 1886, the limitations of DC systems were ing increasingly apparent. They could deliver power only a short distance from generators. To keep transmission power losses (I2R) and voltage drops
Section 1 Introduction
to acceptable levels, voltage levels had to be high for long-distance power transmission. Such high voltages were not acceptable for generation and consumption of power; therefore, a convenient means for voltage transformation became a necessity.
The development of the transformer and AC transmission by L. Gaulard and . Gibbs of Paris, France, led to AC electric power syst