User's Manual

PQ Log
Users Manual
50
• The rated current I
A
which is the nominal current the installation is designed for
• The rated apparent power S
A
• The short circuit apparent power S
kV
at the PCC (Point of Common Coupling)
For each harmonic current I
n
there is limit value which can be calculated from these basic
parameters. The PQ Log software is able now to adapt these limits for specific
installations where the measurements were taken.
The mathematical formulae are: calculation of limit values for each current harmonic
with orders of n = 2 up to n = 50.
A
A
kVn
n
I
S
SP
I ⋅⋅=
1000
The parameter p
n
can be found in the following table:
Harmonic order n 3 5 7 11 13 17 19 >19
p
n
6 15 10 5 4 2 1.5 1
The limit value for the thd I in % is also calculated from the installation specific data:
%100
1000
20
∗⋅=
A
kV
S
S
THDI
These values are proposed in several documents such as the ”TOR D2” issued by the
Austrian E-CONTROL as a recommendation for assessing the impact of distorting loads
to the network.
This document is the basis for a common recommendation D.A.CH.CZ 301/004 which
will be mandatory in the following countries: Austria, Germany, Switzerland, and the
Czech Republic.
To use PQ Log:
1. Take the measurements and transfer the data to your PC from the PQ Log.
2. Open the Software Settings – Limit value level file screen.
3. In the dialog box for current harmonics, click the VSE/VEOE/VDN button.
4. Enter the values specific for the installation under test.
5. Click OK. The values are stored in the limit value file temporarily and can be
modified later for other measurements.
6. If required, the list field ”Parameter P
n
” in the same dialog window presents the
actual multipliers P
n
for each single harmonic of order n.
7. Each of them can be modified by selecting them and/or entering the order and the
new value P
n
and pressing the Set button for future requirements.
8. The button Standard allows restoring of the initial values as recommended by
D.A.CH.CZ 301/004.
9. Click OK to confirm and to quit the dialog.
10. PQ Log calculates the limit values for each current harmonic accordingly.