ABB RELION REX640 Technical Manual page 543

1MRS759142 F
Table 603: Special conditions
Condition
U3P connected to real measurements
URES calculated
UNEUT calculated
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.2.8.5 Operation principle
The function can be enabled and disabled with the
corresponding parameter values are "On" and "Off".
The operation of the third harmonic-based stator earth-fault protection function
can be described using a module diagram. All the modules in the diagram are
explained in the next sections.
GCB_CLOSED
Figure 313: Functional module diagram
3rd harmonic calculation (terminal side)
3rd harmonic calculation calculates the magnitude and phase angle of the third
harmonic voltage at the generator terminal Ū
voltage depends on the availability of terminal side voltage and is specified by the
Voltage selection setting.
Voltage selection setting is set to "No voltage" if phase-to-earth voltages are
•
not available at the terminal side. Even in a situation where only phase-to-phase
voltages are available,
to-phase voltages do not contain a third harmonic component. With
REX640
Technical Manual
U_3H_A
U_3H_B
U3P
U_3H_C
U_3H_RES
URES
U_3H_N
UNEUT
BLOCK
Voltage selection is set to "No Voltage" because phase-
Description
The function can work with at least one volt-
age channel connected.
The function requires that all three voltage
channels from the terminal side are connec-
ted to calculate residual voltage. Setting
connection must be "Wye" in that particular
UTVTR.
The function requires that all three voltage
channels from the neutral side are connec-
ted to calculate residual voltage. Setting
connection must be "Wye" in that particular
UTVTR.
rd
3
Differential
harmonic
calculation
calculation
Bias
calculation
3H_T
Protection functions
Operation setting. The
Timer
Level
t
detector
. Calculation of the third harmonic
VT
VT
OPERATE
START
INT_BLKD
Voltage
543