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4.12.3.4
Analog channel configuration
HCUBPTOC has two analog group inputs which must be properly configured.
Table 1076: Analog inputs
Input
Description
I3P1
Three-phase currents
I3P2
Three-phase unbalance currents
See the preprocessing function blocks in this document for the possible
signal sources.
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.
4.12.3.5
Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are “On” and “Off”.
The three-phase current unbalance protection for shunt capacitor banks operates
on the DFT measurement mode. The operation of HCUBPTOC can be described by
using a module diagram. All the modules in the diagram are explained in the next
sections.
BLOCK
OPERATE
Natural
unbalance
compens-
ation
START
ALARM
Level
detector 1
Level
detector 2
Blocking
logic
Timer 2
t
I3P2
I3P1
I_A
I_UNB_A
I_UNB_B
I_UNB_C
t
Timer 1
t
Figure 633: Function module diagram
Natural unbalance compensation
In the three-phase H-bridge-connected shunt capacitor bank configuration, the
unbalance currents
I_UNB_A
,
I_UNB_B
and
I_UNB_C
are measured at the common
points of the H-bridge.
Protection functions
1MRS759142 F
1132
REX640
Technical Manual