Basics of PFC
功率補償系統的基本知識
 
 Active power P
Power in an electrical installation that is converted to mechanical work or
thermal energy.
有功功率 P: 在電器安裝中轉換為機械能或熱能的功率。
 
 Apparent power S The power drawn by an electrical installation during operation. It consists of the active power P and the reactive power Q.
 
 
視在功率 S: 在電器安裝中操作時所產生的功率，分為有功功率 P 和無功
功率 Q。
 
 Reactive power Q
The power drawn by an electrical installation for operation without being consumed. It is mainly due to the power needed to build up magnetic fields in inductive loads (e.g. in motors).
無功功率 Q: 在電器安裝中操作時沒有被消耗的功率，主要是由于電機等
建立磁場感性負荷所產生的功率。
 
Power factor
The power factor is the ratio of active power P to apparent power S under sinusoidal conditions. 
功率因數：在正弦曲線條件下，有功功率P 和視在功率 S 的比值。 
 
Frequency of the supply voltage
The repetition rate of the fundamental wave of the supply voltage Is measured over a given interval of time. Usually 50 or 60 Hz.
電源電壓的頻率：在一定區間內，電源電壓基波的重復率，通常是 50HZ
或 60HZ。 
 Detuned PFC
A PFC application in which a reactor/capacitor combination is used to Reduction of harmonics by intentionally creating minima in the impedance spectrum at specified frequencies and to protect the capacitors. In contrast to tuned PFC, the LC filter frequency is set at a comfortable distance to the resonant frequencies of the harmonics to avoid overload due to resonance. The filter effect achieved is thus smaller than for tuned PFC, but still sufficient for most applications. Note
that the 3rd harmonic and its multiples cannot be filtered this way. In PFC, the filter frequency is usually expressed in percent as a detuning factor p. Common standard factors are 7% (189 Hz) and 14% (134 Hz). 7% detuning is effective for the 5th, 7th and 11th harmonics. 14% detuning, although often called filtering, actually increases the impedance for the 5th harmonic and upward. The capacitors are protected from harmonic currents in this way, and while no big filter effect is obtained for the power network, the capacitors are not
overloaded and can therefore correct the power factor.
去諧功率補償系統: 在功率補償系統內，電抗器與電容器配合的作用是在
一定頻率內產生最小阻抗值以減少諧波，保護電容器。與調諧功率補償系
統相反，濾波頻率根據諧波的共振頻率設定在一個理想值以減少共振帶來
的負荷過大。濾波所產生的效果小于調諧功率補償系統，但對于大多數應
用來講是有效的。注意3 次諧波以上的倍數不能這樣過濾。在功率補償系
統內，濾波的頻率通常用去諧系數p 表示。普通的標準系數為 7%(189Hz)和 14% (134 Hz)。7%的去諧系數對于 5 次，7 次，和 11 次諧波是有效的。但14%的系數，盡管也稱作濾波，實際上是增加了 5 次以上諧波的阻抗。電容器通過這種方式避免諧波電流。當電力系統內沒有大的濾波時，電容器就不會負荷過大，因而能夠校正功率系數。
Detuning factor p Ratio of the impedances of areactor/capacitor combination in detuned PFC. 
去諧系數 p: 在去諧功率補償系統內，電抗器與電容器之間的阻抗比值.
 
PFC
Abbreviation for Power Factor Correction. Any method to achieve  The abbreviations THD-U and THD-V are commonly used for the voltage terms, which are calculated in the same way as THD-I. Harmonics cause numerous problems in power networks and are increasing because they represent a growing problem for modern electrical and electronic equipment. The 3rd, 5th and 7th harmonics, and odd ones up to the 50th harmonic, are most common.
諧波（電流/電壓）：是指基本頻率的積分倍數。當疊加時，會使正常的正
弦曲線發生畸變。他們通常是對電網基本頻率倍數的(過時)電流和電壓弧
線進行傅立葉級數分解得來的，是其基波電流和電壓的方均根值之比，也
稱為總諧波畸變率（見以上公式）。THDU,THDV 和 THDI 的計算方式相
同。由于現代電力和電子設備問題的日益突出，諧波在電網中所產生的問
題也在增加。3 次，5次，7 次,以及50 次以內的諧波很普遍。 
 IPxx degree of protection A measure of the degree of protection: the first digit refers to electric shock hazards and the second one to the intrusion of unwanted substances.
保護等級 IPXX： 第一個數值是指電力有害物質，第二個數值是指干擾
物質。  
Insulation class Permissible application temperature for the insulation class used in the reactor.
絕緣等級: 是指電抗器產品所允許的應用溫度范圍。 
 Capacitor voltage Uc
Required voltage strength of the capacitor. The series connection of capacitor and reactor causes a voltage rise at the capacitor terminals as described by the following formula which must be considered when selecting a capacitor for the application.

Uc = Un
�1− P
100%
 
電容器電壓 Uc: 是指電容器所需的電壓強度。電容器和電抗器的串聯方式，引起電容器端子的電壓升高。當選擇電容器配合時，應按以上公式考慮電容器的電壓。