Table 1010: Special conditions
Condition
Description
U3P connected to real meas-
urements
The function can work with any two phase voltage channels
connected but it is recommended to connect all three volt-
age channels.
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.
4.8.3.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of DQPTUV can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Reactive
power
monitoring
Under
voltage
detection
BLOCK
OPERATE
START
U3P
I3P
I
1
U
1
U_AB
U_BC
U_CA
Timer
t
Blocking
logic
Figure 599: Functional module diagram
Under voltage detection
Under voltage detection compares the fundamental frequency component of all
three phase-to-phase voltages with the set
Voltage start value. When all three
phase-to-phase voltages are lower than the set
Voltage start value, the Under
voltage detection module sends an enable signal to the Timer indicating an
undervoltage condition at the grid connection point.
Reactive power monitoring
This module calculates and monitors the reactive power based on positive sequence
current and voltage. The use of a positive sequence component makes the
determination of power insensitive to a possible asymmetry in current and voltages.
1MRS759142 F
Protection functions
REX640
Technical Manual
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