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.
4.5.10.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "On" and "Off".
The operation of PHVPTOV can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
Average
calculation
BLOCK
Level
detector
START
OPERATE
Blocking
logic
INITIALIZE
RESET
t
Timer
Phase
selection
logic
U3P
U_A_AB
U_B_BC
U_C_CA
Figure 512: Functional module diagram
Average calculation
The module calculates the average voltage magnitude variation for each of the three
input phase voltages. The calculation is done in three successive aggregations.
• 10/12-cycle voltage input samples are aggregated to calculate the 10/12-cycle
RMS voltage.
• 10/12-cycle RMS voltages are aggregated over a time period of T
refresh
to get the
refresh value.
• Refresh values are aggregated over a time period T
average
to get the average RMS
voltage magnitude.
The
Voltage selection
setting is used for selecting phase-to-earth or phase-to-
phase voltages for protection.
Calculation of 10/12-cycle RMS voltage
The 10/12-cycle RMS voltage is calculated for each of the three input voltages by
applying the standard RMS formula using the voltage samples over a range of 0.2
s. Depending on the
Voltage selection
setting, voltage samples are either phase-to-
earth or phase-to-phase voltage samples.
Calculation of RMS refresh voltage
The RMS refresh voltage is calculated by aggregating the U
10cycles
/ U
12cycles
RMS
voltage over a time period of T
refresh
. The time period T
refresh
depends on the setting
Time interval
.
1MRS759142 F
Protection functions
REX640
Technical Manual
915
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