Beckhoff EL34 Series Documentation page 27

Product overview
Fig. 18: Representation of the power quality factor calculation
As can be seen for the time value 120, the calculation method is chosen in such a way that even very short
voltage drops cause a clear signal deflection.
The value above which the power supply is to be regarded as "sufficiently good" is strongly dependent on the
connected application. The more sensitive the application, the higher the minimum limit value of the PQF
should be.
To adapt the power quality factor to your mains supply, enter the nominal voltage and frequency in CoE
object "0xF801 PMX Total Settings PQF [} 159]". This can also be done via the "Settings" tab, which
summarizes all the important terminal setting options in a user-friendly manner.
Voltage zero crossing
The EL3443 and EL3453 have the ability to determine the exact time of a voltage zero crossing. However, in
order for this to be transmitted to a higher-level controller in a meaningful manner, the controller and the
EtherCAT Terminal must have the same time base. Using distributed clocks technology, an EtherCAT
system provides such a common time base (for details see EtherCAT system description). In order to be able
to use these, the EL3443 must be in "DC synchronous" mode and the EtherCAT master must support the
corresponding function.
Once these basic requirements have been met, the EL3443 and EL3453 provide the DC time of the
penultimate zero crossing. In order to facilitate exact determination of the fundamental wave, the voltage
signal to be evaluated must first be filtered, which inevitably entails a delay. In addition to the time of the
voltage zero crossing, the EL3453 also determines the respective current zero crossings.
Statistical evaluation
In addition to the cyclic data, the EL34xx terminals also produce statistical evaluations over longer periods
(can be set in the CoE: "F803 PMX Time Settings [} 162]"). By default, the "F803:12 Measurement Interval
[} 162]" is set to 15 minutes. The clock available for this purpose in the terminal can not only be read out via
the CoE object "F803:13 Actual System Time [} 162]", it can also be actively influenced. Depending on the
EL34xx Version: 1.5 27