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2857-570/024-001
Functions
Product manual | Version: 2.0.0
35
3-Phase Power Measurement Module, 1 A
LF = sign Q
·
|P| / S
• Positive (plus) sign: Positive reactive power
• Negative (minus) sign: negative reactive power
Note
Jump of power factor LF from +1 to −1
The LF value can jump b1 and −1 when reactive power is very low. This behav-
ior occurs as a result of digitalization noise.
The 4-quadrant representation has the following form:
Figure 16: 4-Quadrant Representation of Active and Reactive Pow er
The four-quadrant display is also presented in the Interface Configuration Software. For
more information, see "Configuration with the Interface Configuration Software."
Phase Angle
The phase angle between voltage and current is calculated for each phase using time-
synchronous sampling. The phase angle is indicated in degrees.
Rotary Field Detection
The zero crossings of the voltage characteristics for the three phases are monitored by
rotary field detection. The direction of rotation of a motor or machine can only be deter-
mined when the phase sequence L1–L2–L3 at the power measurement module has been
connected the same way as at the motor and when the motor corresponds to the guide-
lines of VDE 0530-8 or DIN EN 60034-8 with regard to “Terminal designations and direc-
tion of rotation” (L1 on Uengine, L2 on V engine, L3 on W engine). Phase sequence L1–
L2–L3 signals clockwise rotation; a reversed phase sequence signals counterclockwise
rotation. Caution: It is not possible to detect double reversing.
Tamper Detect (fault current detection)
The “Tamper Detect” function can be used to detect fault currents resulting from defective
machines and equipment. In a three-phase supply network, the following holds in the
fault-free state: The sum of the instantaneous values of the line currents corresponds to
the current in the neutral conductor. Therefore, the power measurement module calcu-
lates the sum of the instantaneous values of the line currents: