Table. 5.2.1 - 23. Harmonic current measurements.
Name
Range
Step Default
Description
Harmonics
calculation values
("Harm Abs.or
Perc.")
-
0: Percent
1:
Absolute
-
0:
Percent
Defines whether the harmonics are calculated as percentage or
absolute values.
Harmonics display
-
0: Per unit
1: Primary
A
2:
Secondary
A
-
0: Per
unit
Defines how the harmonics are displayed: in p.u values, as primary
current values, or as secondary current values.
Maximum
harmonics value
("Ixx maximum
harmonic")
A 0.00...100
000.00
0.01
-
Displays the maximum harmonics value of the selected current
input ILx or I0x.
Fundamental
frequency
("Ixx fundamental")
A 0.00...100
000.00
0.01
-
Displays the current value of the fundamental frequency (RMS)
from the selected current input ILx or I0x.
Ixx harmonics
(2
nd
...31
st
harmonic)
A 0.00…100
000.00
0.01
-
Displays the selected harmonic from the current input ILx or I0x.
5.2.2 Frequency tracking and scaling
Measurement sampling can be set to the frequency tracking mode or to the fixed user-
defined frequency sampling mode. The benefit of frequency tracking is that the measurements are
within a pre-defined accuracy range even when the fundamental frequency of the power system
changes.
Table. 5.2.2 - 24. Frequency tracking effect (FF changes from 6 Hz to 75 Hz).
The measurement error with a fixed 50 Hz sampling frequency
when the frequency changes. The constant current is 5 A, the
frequency sweep is from 6 Hz to 75 Hz.
The measurement error with frequency tracking when the
frequency changes. The constant current is 5 A, the
frequency sweep is from 6 Hz to 75 Hz.
As the figures above show, the sampling frequency has a major effect on the relay's measurement
accuracy. If the sampling is not tracked to the system frequency, for example a 10 Hz difference
between the measured and the set system frequency can give a measurement error of over 5 %. The
figures also show that when the frequency is tracked and the sampling is adjusted according to the
detected system frequency, the measurement accuracy has an approximate error of 0.1...- 0.2 % error
in the whole frequency range.
A
AQ
Q-M210
-M210
Instruction manual
Version: 2.04
64