Operation Principle - ABB RELION REX640 Technical Manual

1MRS759142 C
6.2.5
REX640
Technical Manual

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "on" and "off".
The operation of CCSPVC can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
I_A
I_B
I3P
I_C
Io
IRES
BLOCK
GUID-86A61FFF-4A55-443B-98A1-B6A805774A21 V1 EN
Figure 656: Functional module diagram
Differential current monitoring
Differential current monitoring supervises the difference between the summed phase
currents I_A, I_B and I_C and the reference current I_REF.
The current operating characteristics can be selected with the Start value setting.
When the highest phase current is less than 1.0 × In, the differential current limit is
defined with Start value. When the highest phase current is more than 1.0 × In, the
differential current limit is calculated with the equation.
MAX I A I B I C Start value ( _ , _ , _ ) ⋅
GUID-16BDABDB-5739-4301-B245-A80973EED4E3 V1 EN
The differential current is limited to 1.0 × In.
Timer
Differential
t
current
monitoring
Section 6
Supervision functions
FAIL
ALARM
(Equation 280)
1207