TRIP
Level
detector
1
I_A
I_B
I_C
BLOCK
Level
detector
2
I_G
FLT_ARC
REM_FLT_ARC
ARC_FLT_DET
Operation
mode
selector
t
Dropoff
OPR_MODE
t
Dropoff
A070746-ANSI V2 EN
Figure 371: Functional module diagram
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 residual 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
activated, the operation of the function is based on light information only. When the
OPR_MODE input is deactivated, the operation of the function is based on both light and
current information. When the required criteria are met, the drop-off timer is activated.
Drop-off timer
Once activated, the drop-off timer remains active until the input is deactivated or at least
during the drop-off time. The BLOCK signal can be used to block the TRIP signal or the
light signal output ARC_FLT_DET.
Section 4 1MAC059074-MB A
Protection functions
742 615 series ANSI
Technical Manual
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