请熟悉电力专业英文的人帮忙翻译一下（全部第二章）

Posted 2023-02-16

2-6. Sources of short-circuit current
All sources of short-circuit current and the impedances of these sources must be considered when designing coordinated power system protection.
a. Synchronous generators . When a short-circuit
occurs downstream of a synchronous generator,
the generator may continue to produce output
voltage and current if the field excitation is maintained
and the prime mover continues turning the
generator at synchronous speed. The flow of short-circuit
current from the generator into the fault is
limited only by the generator impedance and
downstream circuit impedances. The magnitude of
generator fault current depends on the armature
and field characteristics, the time duration of the
fault, and the load on the generator. The ability of
a generator to supply current during a fault is a
function of the excitation system.
(1) Some generator excitation systems do not
have the ability to sustain short-circuit current. The
magnitude of fault current is determined by the
generator reactance, and, for such systems, can be
essentially zero in 1.0 to 1.5 seconds.
(2) Static exciters derive excitation voltage
from the generator terminals. Since static exciters
do not sustain short-circuit current, protective devices
on the system will not operate properly, or at
all. Static exciters, therefore, are not recommended.
Static exciters with current boost should be
specified for applications requiring static excitation.
(3) Round-rotor generators with brushless exciters,
typically above 10 MVA, can sustain short-circuit
current for several seconds. Salient-pole
generators less than 10 MVA, also with brushless
exciters, will typically sustain short-circuit current
at 300 percent of generator full load amperes.
b. Synchronous motors. When a short-circuit
occurs upstream of a synchronous motor, the
system voltage goes to zero, and the motor begins
losing speed. As the motor slows down, the inertia
of the load is actually turning the motor and causing
it to act like a generator. The synchronous motor
has a dc field winding, like a generator, and actually
delivers short-circuit current into the fault until the
motor completely stops. As with a generator, the
short-circuit current is limited only by the
synchronous motor impedance and the circuit
impedance between the motor and the fault.
c. Induction motors. With one slight difference,
a short-circuit upstream of an induction motor
produces the same effect as with a synchronous
motor. Since the induction motor has no dc field
winding, there is no sustained field current in the
rotor to provide flux as is the case with a synchronous
machine. Consequently, the short-circuit current
decays very quickly.
d. Supply transformers. Supply transformers are
not sources of short-circuit current. Transformers
merely deliver short-circuit current from the utility
generators to the fault point. In the process,

参考技术A 2 - 6。来源的短路电流

所有资料和阻抗短路电流的一种来源时必须考虑到电力系统继电保护设计协调。

一个。同步发电机。当一短路

一种同步发电机发生的下游,

发电机可以继续输出结果

如果这一个领域电压和电流励磁得以维持

与原动机继续转

发电机在同步速度。短路流

电流发生器到故障

仅限制于发电机阻抗

下游电路阻抗。巨大的

发电机故障电流依赖于盔甲

和现场特点、停留的时间

故障、负荷的发电机。能力的

一个开关电流发生器在断裂带

励磁系统的功能。

(1)一些发电机励磁系统不

有能力维持短路电流。这

故障电流的大小来确定

发电机电抗引入,这种系统中,即可

基本上在1.0到1.5秒的零。

(2)中静态励磁励磁电压

从发生器出来的终端。因为静态励磁

不要维持短路电流,保护装置吗

对系统不能正常运转,或

所有的人。静态励磁,因此不推荐使用。

用静态励磁电流增强应该的

指定程序需要静态励磁。

(3)和无刷励磁发电机Round-rotor,

通常大于10 MVA,能承受短路

当前了好几秒钟。Salient-pole

发电机小于10 MVA,也无刷

励磁,一般会维持短路电流

在300%的发电机满负荷安培。

同步电动机。b。当一短路

一个同步电动机发生的上游

系统电压到零,电机就开始了

失去了速度。马达减速时,其惯性

负载的实际上是将电机和引起

它像一个发电机。的同步电动机

有一个直流励磁绕组,像一台发电机,而实际上吗

提供短路电流的故障,直到进入

汽车完全停止。作为一个发电机

仅限制短路电流的

同步电动机的电路阻抗

阻抗之间的马达和故障。

c。异步电动机。与一个细微差异,

短路上游感应电机

产生同样的效果如同同步

电机。由于感应电机无直流领域

蜿蜒的,没有持续电流的领域

转子提供流量当同步

机器。因此,短路电流

衰减很快。

d。供应变压器。供应变压器

没有来源的短路电流。变压器

仅仅能帮助短路电流从用途

发电机故障点。在这个过程中,