Operation Principle - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.5.10.5
832
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 PHVPTOV can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
U_A_AB
U_B_BC
U3P
U_C_CA
INITIALIZE
RESET
BLOCK
GUID-491566D5-7710-4599-BE4E-A823FC02814B V1 EN
Figure 453: 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 value.
• Refresh values are aggregated over a time period T
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
Average Level
selection
calculation detector
Blocking
logic
1MRS759142 C
Timer
Phase
t
logic
refresh
to get the average RMS
average
Technical Manual
OPERATE
START
to get the
REX640