Beckhoff EL34 Series - Basic Function Principles; Fig. 14 Voltage U and Current I Curves

Product overview
EL34xx 23Version: 1.5
3.3 Basic function principles
Measuring principle
The EL3443 works with 6 analog/digital converters for recording the current and voltage values of all 3
phases.
Recording and processing is synchronous and identical for the 3 phases. The signal processing for one
phase is described below. This description applies correspondingly for all 3 phases.
Fig.14: Voltage u and current i curves
RMS value calculation
The RMS value for voltage and current is calculated during the period T. The following equations are used:
u
(t)
: instantaneous voltage value
i
(t)
: instantaneous current value
n:number of measured values
The instantaneous values for current and voltage are low-pass filtered with a cut-off frequency of 2.5 kHz for
the EL3443, EL3423 and EL3483.
Active power measurement
The EL34xx measures the active power P according to the following equation
P: active power
n: number of samples
u
(t)
: instantaneous voltage value
i
(t)
: instantaneous current value