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THD sliding mean value outputs are
SMNTHD_A
,
SMNTHD_B
and
SMNTHD_C
. Non-
sliding 10-minute mean values LMNTHD_A, LMNTHD_B and LMNTHD_C are seen
in the monitored data. These values are always shown as percentage of the
fundamental frequency current mean value. The 10-minute mean values follow 10
min ticks. See also
and the description for sliding values.
10.1.5.3
Total demand distortion
The total demand distortion TDD is calculated from the measured harmonic
components with the formula
TDD
I
I
h
L
h
n
=
=
∑
2
2
(Equation 391)
I
h
h
th
harmonic component
I
L
Maximum demand load current set with
Demand current setting
n
Number of harmonics
The used reference current is the absolute value of the
Demand current setting. It is
typically set according to the maximum load current of the feeder. The TDD value is
calculated separately for each phase.
TDD sliding mean value outputs are
SMNTDD_A
,
SMNTDD_B
and
SMNTDD_C
. Non-
sliding 10-minute mean values LMNTDD_A, LMNTDD_B and LMNTDD_C are seen in
the monitored data. These values are always shown as percentage of the setting
Demand current. The 10-minute mean values follow 10 min ticks. See also
and the description for sliding values.
10.1.5.4
Harmonic calculation
Harmonic mean values are calculated for each phase. Also, the mean values of the
nominal frequency (fundamental) and direct current component are calculated. The
fundamental frequency mean values are shown as percentage of the nominal phase
current.
The actual harmonic mean values are shown as percentage of the reference current.
By default, the fundamental frequency current is used as reference. This can
be selected by setting
Reference Cur Sel to "fundamental". When amplitude of
fundamental frequency current is very low, below 0.02 xIn, calculation is blocked
internally. As a result, value zero is used in the mean value calculation. Extremely
high harmonic values are limited to 2.0 xIn. This is also used for fundamental mean
value, but not for reference.
The value of Demand current setting can be used as reference by setting
Reference
Cur Sel to "absolute". Typically, it is set according to the maximum demand load
current. That is more typically used when TDD is preferred, but might also be found
useful when THD is monitored.
Settings
Reference Cur Sel and Demand current have no effect in THD
calculation, but setting
Demand current is used in TDD calculation.
Power quality measurement functions
1MRS759142 F
1810
REX640
Technical Manual
Содержание RELION REX640
Страница 1: ... RELION PROTECTION AND CONTROL REX640 Technical Manual ...
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Страница 3: ...Document ID 1MRS759142 Issued 2023 02 07 Revision F Copyright 2023 ABB All rights reserved ...
Страница 167: ...Figure 62 Signal outputs in power supply module 1MRS759142 F Basic functions REX640 Technical Manual 167 ...
Страница 184: ...Figure 84 mA channels working as mA outputs Basic functions 1MRS759142 F 184 REX640 Technical Manual ...
Страница 1868: ...Figure 989 ANSI extremely inverse time characteristics General function block features 1MRS759142 F 1868 REX640 Technical Manual ...
Страница 1869: ...Figure 990 ANSI very inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1869 ...
Страница 1870: ...Figure 991 ANSI normal inverse time characteristics General function block features 1MRS759142 F 1870 REX640 Technical Manual ...
Страница 1874: ...Figure 995 ANSI long time inverse time characteristics General function block features 1MRS759142 F 1874 REX640 Technical Manual ...
Страница 1875: ...Figure 996 IEC normal inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1875 ...
Страница 1876: ...Figure 997 IEC very inverse time characteristics General function block features 1MRS759142 F 1876 REX640 Technical Manual ...
Страница 1877: ...Figure 998 IEC inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1877 ...
Страница 1878: ...Figure 999 IEC extremely inverse time characteristics General function block features 1MRS759142 F 1878 REX640 Technical Manual ...
Страница 1882: ...Figure 1002 RI type inverse time characteristics General function block features 1MRS759142 F 1882 REX640 Technical Manual ...
Страница 1885: ...Figure 1004 UK rectifier inverse time characteristic 1MRS759142 F General function block features REX640 Technical Manual 1885 ...
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