110kv变电站设计外文翻译

General Requirements to Construction of Substation

Substations

are

a

vital

element

in

a

power

supply

system

of

industrial

enterprises

．

They serve to receive

，

convert and distribute electric energy .Depending

on power and purpose ,the substations are divided into central distribution substations

for

a

voltage

of

110-500kV;main

step-down

substations

for110-220/6-10-35kV;deep

entrance

substations

for

110-330/6-10Kv;distribution

substations

for

6-10Kv;shop

transformer substations for 6-10/0.38-0.66kV

.At the main step-down substations, the

energy

received

from

the

power

source

is

transformed

from

110-220kV

usually

to

6-10kV(sometimes

35kV)

which

is

distributed

among

substations

of

the

enterprise

and is fed to high-voltage services.

Central

distribution

substations

receive

energy

from

power

systems

and

distribute it (without or with partial transformation) via aerial and cable lines of deep

entrances at a voltage of 110-220kV over the enterprise territory .Central distribution

substation differs from the main distribution substation in a higher power and in that

bulk of its power is at a voltage of 110-220kV;it features simplified switching circuits

at primary voltage; it is fed from the power to an individual object or region .Low-and

medium-power

shop

substations

transform

energy

from

6-10kV

to

a

secondary

voltage of 380/220 or 660/380.

Step-up

transformer

substations

are

used

at

power

plants

for

transformation

of

energy

produced

by

the

generators

to

a

higher

voltage

which

decreases

losses

at

a

long- distance transmission .Converter substations are intended to convert AC to DC

(sometimes vice versa) and to convert energy of one frequency to another .Converter

substations

with

semiconductor

rectifiers

are

convert

energy

of

one

frequency

to

another

.Converter

substations

with

semiconductor

rectifiers

are

most

economic.

Distribution

substations

for

6-10kV

are

fed

primarily

from

main

distribution

substations

(sometimes

from

central

distribution

substations).With

a

system

of

dividing substations for 110-220kV

, the functions of a switch- gear are accomplished

by switch-gears for 6-10kV at deep entrance substations.

Depending on location of substations their switch-gear may be outdoor or indoor.

The

feed

and

output

lines

at

6-10kV

substations

are

mainly

of

the

cable

type .at

35-220kV

substations

of

the

aerial

type

.When

erecting

and

wiring

the

substations ,major attention is given to reliable and economic power supply of a given

production.

Substations

are

erected

by

industrial

methods

with

the

use

of

large

blocks

and

assemblies

prepared

at

the

site

shops

of

electric

engineering

organizations

and

factories

of

electrical

engineering

industry

.Substations

are

usually

designed

for

operation

without

continuous

attendance

of

the

duty

personnel

but

with

the

use

of

elementary automatic and signaling devices.

When

constructing

the

structural

part

of

a

substation

.it

is

advisable

to

use

light- weight

industrial

structures

and

elements

(panels

,floors

,etc.)

made

of

bent

sections

.These

elements

are

pre-made

outside

the

erection

zone

and

are

only

assembled at site .This considerably cuts the terms and cost of construction.

Basic circuitry concepts of substations are chosen when designing a powersupply

system of the enterprise .Substations feature primary voltage entrances .transformers

and

output

cable

lines

or

current

conductors

of

secondary

voltage .Substations

are

mounted

from

equipment

and

elements

described

below .The

number

of

possible

combinations of equipment and elements is very great .Whenelaborating a substation

circuitry

,it

is

necessary

to

strive

for

maximum

simplification

and

minimizing

the

number

of

switching

devices

.Such

substations

are

more

reliable

and

economic .Circuitry

is

simplified

by

using

automatic

reclosure

or

automatic

change

over

to

reserve

facility

which

allows

rapid

and

faultless

redundancy

of

individual

elements and using equipment.

When designing transformer substations of industrial enterprises for all voltages ,

the following basic considerations are taken into account:

1.

Preferable

employment

of

a

single-bus

system

with

using

two-bus

systems

only to ensure a reliable and economic power supply;

2. Wide use of unitized constructions and busless substations;

1

ntiated employment of automatics and telemetry if the substation design

does not envisage the use of automatics or telemetry ,the circuitry is so arranged as to

allow for adding such equipment in future without excessive investments and re-work.

of

simple

and

cheap

devices-isolating

switches

,short-circuiting

switches ,load-breaking isolators ,fuses ,with due regard for their switching capacity

may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air

switches .Substation and switch-gear circuitries are so made that using the equipment

of each production line is

fed from individual transformers ,assemblies ,the lines to

allow

their

disconnection

simultaneously

with

mechanisms

without

disrupting

operation of adjacent production flows.

When

elaborating

circuitry

of

a

substation,

the

most

vital

task

is

to

properly

choose

and

arrange

switching

devices(switches

,isolators

,current

limiters

,arresters

,high-voltage

fuses).The

decision

depends

on

the

purpose

,power

and significance of the substation.

Many years ago, scientists had very vague ideas about electricity. Many of them

thought of it as a sort of fluid that flowed through wires as water flows through pipes,

but they could not understand what made it flow. Many of them felt that electricity

was

made

up

of

tiny

particles

of

some

kind

,but

trying

to

separate

electricity

into

individual particles baffled them.

Then,

the

great

American

scientist

Millikan,

in

1909,astounded

the

scientific

world by actually weighing a single particle of electricity and calculating its electric

charge.

This

was

probably

one

of

the

most

delicate

weighing

jobs

ever

done

by

man,for a single electric particle weighs only about half of a millionth of a pound. To

make up a pound it would take more of those particles than there are drops of water in

the Atlantic Ocean.

They

are

no

strangers

to

us,

these

electric

particles,

for

we

know

them

as

electrons. When large numbers of electrons break away from their atoms and move

through a wire,we describe this action by saying that electricity is flowing through the

,the

electrical

fluid

that

early

scientists

talked

about

is

nothing

more

than

electrical flowing along a wire.

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But how can individual electrons be made to break away from atoms? And how

can these free electrons be made to along a wire? The answer to the first question lies

in the structure of the atoms themselves. Some atoms are so constructed that they lose

electrons

easily.

An

atom

of

copper,

for

example

,is

continually

losing

an

electron,

regaining it(or another electron),and losing it again. A copper atom normally has 29

electrons,

arranged

in

four

different

orbits

about

its

nucleus.

The

inside

orbit

has

2

electrons. The next larger orbit has third orbit is packed with 18 electrons . And

the outside orbit has only one is this outside electron that the copper atom

is

continually

losing,

for

it

is

not

very

closely

tied

to

the

atom.

It

wanders

off,

is

replaced by another free-roving electron, and then this second electron also wanders

away.

Consequently,in a copper wire free electrons are floating around in all directions

among the copper , even through the copper wire looks quite motionless to

your ordinary eye, there is a great deal of activity going on inside it. If the wire were

carrying electricity to an electric light or to some other electrical device, the electrons

would not be moving around at random. Instead, many of them would be rushing in

the same direction-from one end of the wire to the other.

This brings us to the second question .How can free electrons be made to move

along a wire? Well ,men have found several ways to do that .One way is chemical.

V

olta,s

voltaic

pile,or

battery,

is

a

chemical

device

that

makes

electricity(or

electrons)flow in wires. Another way is magnetic. Faraday and Henry discovered how

magnets could be used to make electricity flow in a wire.

Magnets

Almost

everyone

has

seen

horseshoe

magnets-so

called

because

they

are

shaped

like horseshoes. Probably you have experimented with a magnet, and noticed how it

will

pick

up

tacks

and

nails,

or

other

small

iron

objects.

Men

have

known

about

magnets for thousands of years.

Several thousand years ago, according to legend, a shepherd named Magnes lived

on

the

island

of

Crete,

in

the

Mediterranean

Sea .He

had

a

shepherds

crook

tipped

with

iron.

One

day

he

found

an

oddly

shaped

black

stone

that

stuck

to

this

iron

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