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Chapter 4 Electric Machinery
电
机
Section 4
Transformer
变压器
Types and construction of transformer
变压器的种类和结构
A transformer is a device that
changes AC electric energy at one
voltage level into AC electric energy
at another voltage level through
the
action of a magnetic field.
变压器是一种设备，
这种设备通过磁场的作用将一种电压等级的交流电转换成另
一种电压
等级的交流电。
It
consists
of
two
or
more
coils
of
wire
wrapped
around
a
common
ferromagnetic core.
变压器油了两个或多个缠绕公用铁芯上的线圈组成。
These coils are (usually) not directly
connected.
这些线圈通常不是直接连接在一起的。
The
only
connection
between
the
coils
is
the
common
magnetic
flux
present
within the core.
线圈之间唯一的连接时存在于铁芯中的公共的磁通。
One
of
the
transformer
windings
is
connected
to
a
source
of
AC
electric
power,
其中一个变压器的线圈与交流电源连接，
and
the
second
(and
perhaps
third)
transformer
winding
supplies
electric
power to loads.
第二个变压器的线圈（可能是第三个线圈）向负载提供电功率。
The transformer winding connected to
the power source is called the
primary
winding or input winding,
与电源连接的变压器绕组被称为一次绕组或输入绕组，
and the winding connected to the loads
is called the secondary winding
or
output winding.
而与负载直接相连的绕组被称为二次绕组或输入绕组。
If
there
is
a
third
winding
on
the
transformer,
it
is
called
the
tertiary
winding.
如果变压器有第三个绕组，这个然组被称为三次绕组。
Power
transformers are constructed on one of two types
of cores.
电力变压器铁芯的结构分为两类。
One
type
of
construction
consists
of
a
simple
rectangular
laminated
piece
of steel with the
transformer windings wrapped around two sides of
the
rectangle.
一类是由变压器绕组缠绕在一
个简单的矩形钢片叠压成的铁心两边而构成。
This
type of construction is know as core form.
这种变压器的结构称为芯式。
The
other
type
consists
of
a
there-legged
laminated
core
with
the
windings
wrapped around the
center leg.
另一类是由变压器绕组缠绕在一个三柱叠片铁心中间的那个铁
心柱上而构成的。
This type of
construction is know as shell form.
这种类型的结构被称为壳式。
In
either
case,
the
core
is
constructed
of
thin
laminations
electrically
isolated from
each other in other in order to reduce eddy
currents to a
minimum.
无论哪种形
式，铁心都是由彼此间相互电气绝缘的薄叠片构成把涡流
减小到最小程度。
The primary and
secondary windings in a physical transformer are
wrapped one on top of the other with
the low-voltage winding innermost.
实际变压
器的一次绕组和二次绕组在绕的时候把其中的低压绕组绕在铁心的最
里面，然而把另一绕
组绕在外面。
Such an arrangement
serves two purposes:
这样安排绕组的目的有两个：
(i)
It
simplifies
the
problem
of
insulating
the
high-voltage
winding
from
the core.
（<
/p>
1
）这样可以使高压绕组和铁心之间的绝缘问题得到简化。
(ii) It results in much less
leakage flux than would be the two windings
were separated by a distance on the
core.
（
2
）这样可以使产生的
漏磁通比两个绕组隔开一定距离绕在铁心时产生的漏磁
通少得多。
Power
transformers are given a variety of different
names,depending
on their use in power
systems.
电力变压器有各种不同的名称，这取决于它们在电力系统中的作用
。
A transformer connected
to the output of a generator and used to step
its voltage up to the transmission
levels is sometimes called a unit
transformer.
与发电机输出端相连并被用来使输
出电压升高至传输大小的变压器又是被称为
单元变压器。
The transformer at the other end of
the transmission line, which
steps
the
voltage
down
from
transmission
levels
to
distribution
levels, is
called a substation transformer.
和输电线路
另一端相连用来使电压从传输时的大小降低至配电大小的变压器被
称为配电变压器。
Finally, the transformer
that takes the
distribution voltage and
steps
it
down
to
the
final
voltage
at
which
the
power
is
actually
used
is
called
a distribution transformer.
最后，
得到配电电压并把它降低至电力实际被使用的最终电压的变压器被称为配
电变压器。
All these
devices are essentially the same in their
construction,
所有这些设备实质上它们的结构是相同的，
the only difference among them is
their intended use.
它们之间唯一的不同是其预期用途。
In addition to the
various power transformers,
除了不同种类的变压器外，
two
special-purpose transformers are used with
electric machinery and
power systems.
还有两种特殊用途变压器被用来和电机和电力系统一起使用。
The first of these special transformers
is a device specially designed
to
sample a high voltage and produce a low secondary
voltage directly
proportional to it.
第一种变压器是特别设计来取样高电压，
然后产生一个与之成正比的
低的二次电
压。
Such a
transformer is called a potential transformer.
这种变压器被称为电压互感器。
A
power
transformer
also
produces
a
secondary
voltage
directly
proportional to its
primary voltage;
电力变压器也会产生一个正比于其一次侧电压的二次电压；
the difference between a potential
transformer and a power transformer
is
that
the
potential
transformer
is
designed
to
handle
only
a
very
small
current.
电压互感器和电力变压器之间的区别在于电
压互感器只是处理非常小的电流。
The second
type of special transformer is a device designed
to provide
a
secondary
current much smaller
than
but
directly
proportional
to
its
primary current.
第二类特种变压器是专门用于提供比一次侧电流小得多却正比于一次侧电流的
二
次侧电流。
This device is called
a current transformer.
这种器件被称为电流互感器。
Equivalent
circuit of transformer
变压器的等效电路