技术与服务热线:400 820 0372

中国CN  

Why is the Theoretical Calulated Three-Phase Apparent Power Values (ΣVA and ΣS) Different From the Measured Values?

This is due to measurement and calculation error, or differences in calculation methods.
 
On the WT, the three-phase apparent power (ΣS) equation is calculated under the assumption of a balanced condition (the absolute value of each phase is the same, and the phase angle is 120°). When balanced, the line to line voltages U1, U2, and U3 in three-phase three-wire or 3V3A configuration result in phase voltages of √3 times UR, US, and UT. Considering the three-phase apparent power, three-phase four wire is simply the sum of each phase:
                        Three-phase four-wire ΣS = S1+S2+S3

For three-phase three-wire and three-phase three-wire (3V3A), the apparent power is, in princicple, not measured. Therefore when balanced, a coefficient is used such that the same value as three-phase four-wire ΣS, and the following equations are used:
                     Three-phase three-wire ΣS = √3/2(S1+S3)
                     3V3AΣS = √3/3(S1+S2+S3).
 
Consequently, when unbalanced, since the phase-to-phase phase angle is not 120°, and the votlage value of each phase is of a different size, the line to line voltages U1, U2, and U3 above do not result in phase voltages of √3 times UR, US, and UT. Therefore, ΣS calculated for three-phase three-wire or 3V3A can differ from the value of ΣS determined in a three-phase four-wire configuration.

相关产品和解决方案

PZ4000功率分析仪

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

WT3000高精度功率分析仪提供最高精度的测量。此产品已成为行业标准,用于变频器、电机驱动器、照明系统和电子镇流器、UPS系统、飞机电力系统、变压器测试和其它电力转换设备的研发。WT3000的基本功率精度达0.02%,带宽为1MHz。

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。

返回顶部
WeChat QR Code
微信扫一扫
获得更多专业服务