Beckhoff EL3773 - Technology; Fig. 10 Voltages in Three-Phase Mains Supply of Central Europe

Product overview
EL377316 Version: 2.5
3.3 Technology
Measurement of AC variables with the EL3773
Normal three-phase mains supply
The normal 3-phase low-voltage grids in Central Europe are characterized by the following interrelationship:
rated voltage is usually the effective voltage U
RMS
, e.g. 230 V
RMS
, as a star voltage between one of the three
live conductors (L1, L2 or L3) and neutral N.
Fig.10: Voltages in three-phase mains supply of Central Europe
With a pure sinusoidal oscillation (unloaded grid) a maximum peak voltage (max. amplitude) of approx.
±325V
peak
to N is calculated from the then valid crest factor from in the star voltage.
A phase-to-phase voltage of (RMS) can be measured between the live
conductors.
RMS value specifications
Note
RMS value (
rms
) specifications
All AC value specifications in this documentation such as RMS specifications (
rms
) refer to a
50/60Hz 3-phase mains network with a sinusoidal waveform.
The EL3773 EtherCAT Terminal is a power monitoring terminal for state monitoring of a 3-phase AC voltage
system. The following properties are characteristic of the EL3773:
• 3 channels measure -410 to +410V to N through analog-to-digital converters in 16-bit resolution as
amplitude value
• 3 channels measure -1.5 to +1.5A to N through analog-to-digital converters in 16-bit resolution as
amplitude value
• all 6 analog input channels are measured simultaneously
• the EL3773 is an oversampling terminal and can therefore record not just 1, but up to 100 samples
(amplitude values) per channel in each PLC/EtherCAT cycle. These are sent as a data packet to the
controller via the cyclic process data.
The minimum sampling time is 100µs, corresponding to 10,000 samples/second.