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Why is the Theoretical Calculated Power Factor and Phase Angle Different Than the Measured Values?

When measuring input signals of distorted waves, signals that are DC-offset or signals that include superimposed harmonic components, will result in different values for power factor and phase angle than those expected with sine waves. 
  1. When a single phase is being measured, the WT performs calculations as follows:
           Power factor = active power/apparent power (apparent power = voltage x current)
           Phase angle = cos-1 (active power/apparent power)

    Therefore, the power factor and phase angle of input signals of distorted, DC-offset, or superimposed harmonic component inclusive waves will differ from the power factor and phase angle of the fundamental wave. Also, on other measuring instruments, the measuring or calculation method may differ from that of the WT, so the power factor and phase angle values may also differ.
    Additionally, for a power factor close to 0 (phase angle of voltage and current is close to 90°), slight measurement error in the measured values of voltage, current, and power will affect the power factor and phase angle values.
    Check that the measuring range is set appropriately, and check that the calculation error attributable to the error in voltage, current, and power is within that range.

  2. On the WT, the following calculations are used for three-phase three-wire or 3V3A configurations:
           Σpower factor = Σactive power/Σapparent power
           Σphase angle = cos-1 (Σactive power/Σapparent power)

    Therefore, the source of error in the Σapparent power value is the source of error in the value of Σpower factor or Σphase angle. The power factor (value calculated as active power/apparent power) in the case of a distorted waveform is called the total power factor.
    The apparent power increases with distortion of the waveform, and the power factor (calculated value) becomes less accurate.
    "Phase compensation" (or "power-factor improvement") can be thought to mean, in addition to resolving phase differences in the voltage and current, improving the waveform distortion.

相关产品和解决方案

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PZ4000设计用于高频功率测量以及瞬时功率测量。此仪器的实时采集系统可执行按周期的功率测量。一到四个输入单元提供0.2%的基本精度,具备2MHz的带宽和5MS/秒的数字化速率。

高性能功率分析仪 WT1800系列

高端WT1800是WT1600的升级产品,可应用于从节能到高负载应用在内的各种应用领域。WT1800拥有6单元输入能力,可提供最大的灵活性和5MHz带宽下0.1%的基本功率精度。

高精度功率分析仪 WT3000

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数字功率分析仪

功率计或称瓦特计,可以测量产生、转换或消耗电能的设备各项特征,包括设备的各项参数,如:功率(瓦特)、功率因数、谐波和效率等等。

YOKOGAWA数字功率分析仪,性能优越、测量可靠,支持各种应用,非常值得拥有。尤其是YOKOGAWA WT300E功率计,已经在全球功率计市场份额上遥遥领先。

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