ABB Relion 650 Series Technical Manual page 170

Section 6
Current protection
6.4.6 Monitored data
Table 81:
Name
DIR_A
DIR_B
DIR_C
IA
IB
IC
6.4.7 Operation principle
The function is divided into three different sub-functions, one for each step. For each step x ,
where x is step 1, 2, 3 and 4, an operation mode is set by
Forward / Reverse .
The protection design can be decomposed in three parts:
• The direction element
• The four step over current function
• The mode selection
The sampled analog phase currents are processed in a pre-processing function block. Using a
parameter setting
protection OC4SPTOC (51_67) function, it is possible to select the type of the measurement used
for all overcurrent stages. It is possible to select either discrete Fourier filter (
filter ( RMS ).
If DFT option is selected then only the RMS value of the fundamental frequency components of
each phase current is derived. Influence of DC current component and higher harmonic current
components are almost completely suppressed. If
is used. The true RMS value in addition to the fundamental frequency component includes the
contribution from the current DC component as well as from higher current harmonic. The
selected current values are fed to OC4SPTOC (51_67).
In a comparator, for each phase current, the DFT or RMS values are compared to the set operation
current value of the function (
than the set operation current, outputs PICKUP, PU_STx, PU_A, PU_B and PU_C are, without delay,
164
OC4SPTOC (51_67) Monitored data
Type Values (Range)
INTEGER
INTEGER
INTEGER
REAL
REAL
REAL
If VT inputs are not available or not connected, setting parameter
shall be left to default value,
MeasType within the general settings for the Four step phase overcurrent
Pickup1 , Pickup2 , Pickup3 or Pickup4 ). If a phase current is larger
© Copyright 2011 ABB Power Grids. All rights reserved
Unit
0=No direction -
1=Forward
2=Reverse
0=No direction -
1=Forward
2=Reverse
0=No direction -
1=Forward
2=Reverse
- A
- A
- A
DirModeSelx : Disabled / Non-directional /
Non-directional .
RMS option is selected then the true RMS values
1MRK 506 326-UUS B
Description
Direction for phase A
Direction for phase B
Direction for phase C
Current in phase A
Current in phase B
Current in phase C
GUID-6270222E-983D-4CFE-9F9D-3DB8F73EE8F3 v2
DirModeSelx
DFT ) or true RMS
Line distance protection REL650
Technical manual
PID-2351-MONITOREDDATA v6