Operation Principle - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.5.7.5
802
There are a few special conditions which must be noted with the configuration.
Table 765: Special conditions
Condition
U3P connected to real measurements
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.

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of OEPVPH can be described using a module diagram. All the modules
in the diagram are explained in the next sections.
I_A
I_B
I3P
I_C
I
1
U_A_AB
U_B_BC
U_C_CA
U3P
U
1
F
BLOCK
GUID-2971C04F-FF22-432B-8FA2-526920D24F6D V1 EN
Figure 436: Functional module diagram
U/f calculation
This module calculates the U/f ratio, that is, the excitation level from the internal
induced voltage (E) and frequency. The actual measured voltage (U
the internal induced voltage (E), a value the equipment has to withstand. This voltage
compensation is based on the load current (I
Description
The function can work with at least one voltage
channel connected (A, B or C according to
selection "1", "2" or "3") if Voltage selection is set to
"phase-to-earth".
The function can work with any two voltage
channels connected (AB, BC or CA according to
Phase selection "1", "2" or "3") if Voltage selection
is set to "phase-to-phase".
The function requires that all three voltage
channels are connected if
to "pos sequence".
Level
detector
U/f
calculation
Blocking
logic
) and the leakage reactance (X
L
1MRS759142 C
Phase
Voltage selection is set
Timer
OPERATE
t
START
BLK_RESTART
t
COOL_ACTIVE
) deviates from
m
) of the
leak
REX640
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