相位安装（Ur
=400 V），吸收300 kW的平均功率。
根据表2，在与终
功率因数（0.93），以及与启动功率因数对应的行
（0.8），Kc的值
（0.355）可以读取。无功功率Qc
这必须
本地生成的应为：
质量控制
=千卡
. P=0.355。300=106.5 Kvar
由于功率因数校正的影响，吸收的电流减少
从540 A到460 A（减少约15%）。
功率因数校正电容器组的特性
提高功率因数的经济方法，尤其是对于
已经存在的装置正在安装电容器。
电容器具有以下优点：
-与同步补偿器和电子功率相比成本低
变流器；
-易于安装和维护；
-减少损耗（在低压下小于0.5 W/kvar）；
-可能涵盖广泛的功率和不同的负荷曲线，
简单地并行提供不同的组件组合，每个组件具有
相对较小的功率。
缺点是对过电压和非线性负载的存在很敏感。
适用于功率因数校正电容器的标准如下
跟随：
-IEC 60831-1“交流自愈型并联电力电容器。
额定电压1000V及以下的系统.1部分：总则
-性能、试验和额定值.安全要求.安装指南
和操作”；
-IEC 60931-1“交流用非自愈型并联电力电容器。
额定电压1000V及以下的系统.1部分：一般性能、试验和额定值.安全要求.安装指南
和操作”。
428电气设备| ABB
3功率因数校正
3.1一般方面
Ur=线路电压系统
铭牌上给出的电容器特性为：
•额定电压Ur
，电容器必须无限期承受；
•额定频率f
r
（通常等于网络）；
•额定功率Qc
，通常表示为kvar（电容器的无功功率
银行）。
根据这些数据，可以通过以下方式找到电容器的尺寸特性：
使用以下公式（5）：
在三相系统中，为了提供相同的无功功率，星形连接需要一个电容器，其电容比
三角形连接电容器。
此外，具有星形连接的电容器将受到
a电压√3降低并通过电流√3高于电容器
插入并三角形连接。
通常为电容器提供连接放电电阻，其计算目的是在3分钟内将端子处的残余电压降至75 V，
如参考标准所述。
3.2功率因数校正方法
单功率因数校正
通过连接
将正确值的电容器直接连接到设备的端子
吸收无功功率。
安装简单且经济：电容器和负载可以使用相同的
过载和短路保护，以及连接和断开
同时
cosν的调整是系统和自动的，不仅有利于
能源分配权限，也要向整个内部分配
用户的系统。
这种功率因数校正适用于具有
恒定负载和功率因数，连接时间长。
单个PFC通常应用于电机和荧光灯。电容器
装置或小型照明电容器直接连接到负载。
1SDC01005F0901
单相
联系
电容器组的容量
三相星形连接三相三角形连接
部件的额定电流
线路电流
2 r r r
c
f.U
Q C⋅ = ≠ 2 r r r
c
f.U
Q C⋅ = ≠ 2 f 3 2⋅ ⋅ =
r r
c
U
Q C≠
rc 2 r C Ur I=≠f⋅ ⋅
I=l Irc I=l Irc I l=Irc⋅ 3.

phase installation (Ur = 400 V) which absorbs an average power of 300 kW. From Table 2, at the intersection of the column corresponding to the final power factor (0.93), and the row corresponding to the starting power factor (0.8), the value of Kc (0.355) can be read. The reactive power Qc which must be generated locally shall be: Qc = Kc . P = 0.355 . 300 = 106.5 Kvar Due to the effect of power factor correction, the current absorbed decreases from 540 A to 460 A (a reduction of approximately 15%). Characteristics of power factor correction capacitor banks The most economical means of increasing the power factor, especially for an installation which already exists, is installing capacitors. Capacitors have the following advantages: - low cost compared with synchronous compensators and electronic power converters; - ease of installation and maintenance; - reduced losses (less than 0.5 W/kvar in low voltage); - the possibility of covering a wide range of powers and different load profiles, simply supplying in parallel different combinations of components, each with a relatively small power. The disadvantages are sensitivity to overvoltages and to the presence of nonlinear loads. The Standards applicable to power factor correction capacitors are as follows: - IEC 60831-1 “Shunt power capacitors of the self-healing type for a.c. systems having a rated voltage up to and including 1000 V - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation”; - IEC 60931-1 “Shunt power capacitors of the non-self-healing type for a.c. systems having a rated voltage up to and including 1000 V - Part 1: GeneralPerformance, testing and rating - Safety requirements - Guide for installation and operation”. 428 Electrical devices | ABB 3 Power factor correction 3.1 General aspects Ur = line voltage system The characteristics of a capacitor, given on its nameplate, are: • rated voltage Ur , which the capacitor must withstand indefinitely; • rated frequency f r (usually equal to that of the network); • rated power Qc , generally expressed in kvar (reactive power of the capacitor bank). From this data it is possible to find the size characteristics of the capacitors by using the following formulae (5): In a three-phase system, to supply the same reactive power, the star connection requires a capacitor with a capacitance three times higher than the delta-connected capacitor. In addition, the capacitor with the star connection results to be subjected to a voltage √3 lower and flows through by a current √3 higher than a capacitor inserted and delta connected. Capacitors are generally supplied with connected discharge resistance, calculated so as to reduce the residual voltage at the terminals to 75 V in 3 minutes, as stated in the reference Standard. 3.2 Power factor correction method Single PFC Single or individual power factor correction is carried out by connecting a capacitor of the correct value directly to the terminals of the device which absorbs reactive power. Installation is simple and economical: capacitors and load can use the same overload and short-circuit protection, and are connected and disconnected simultaneously. The adjustment of cosϕ is systematic and automatic with benefit not only to the energy distribution authority, but also to the whole internal distribution system of the user. This type of power factor correction is advisable in the case of large users with constant load and power factor and long connection times. Individual PFC is usually applied to motors and fluorescent lamps. The capacitor units or small lighting capacitors are connected directly to loads. 1SDC010005F0901 Single-phase connection Capacity of the capacitor bank Three-phase star-connection Three-phase delta-connection Rated current of the components Line current 2 2 r r c f U Q C ⋅ = ≠ 2 2 r r c f U Q C ⋅ = ≠ 2 f 3 2 ⋅ ⋅ = r r c U Q C ≠ rc 2 r C Ur I = ≠f ⋅ ⋅ I =l Irc I =l Irc I l = Irc ⋅ 3