ABB RELION 620 Series Technical Manual page 556

Section 5
Protection-related functions
5.5.4
550
The function contains a blocking functionality. Blocking deactivates all outputs and resets
timers.
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of arc protection can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
I_A
Level
I_B detector
I_C
Level
I_G detector
OPR_MODE
REM_FLT_ARC
FLT_ARC
BLOCK
A070746-ANSI V2 EN
Figure 270: Functional module diagram. I_A, I_B and I_C represent phase currents.
Level detector 1
The measured phase currents are compared phasewise to the set Phase pickup value. If the
measured value exceeds the set Phase pickup value, the level detector reports the
exceeding of the value to the operation mode selector.
Level detector 2
The measured ground currents are compared to the set Ground pickup value. If the
measured value exceeds the set Ground pickup value, the level detector reports the
exceeding of the value to the operation mode selector.
Operation mode selector
Depending on the Operation mode setting, the operation mode selector makes sure that all
required criteria are fulfilled for a reliable decision of an arc fault situation. The user can
select either "Light+current", "Light only" or "BI controlled" operation mode. The
operation is based on both current and light information in "Light+current" mode, on light
information only in "Light only" mode or on remotely controlled information in "BI
controlled" mode. When the "BI controlled" mode is in use and the OPR_MODE input is
1
Operation
mode
selector
2
1MAC504801-IB E
Dropoff
TRIP
t
Dropoff
ARC_FLT_DET
t
620 series ANSI
Technical Manual