ABB 615 series Technical Manual page 486

Section 4
Protection functions
480
(Trip value) in the IDMT equations presented in the Standard inverse-time characteristics
section.
A timer reset state is activated when a drop-off situation happens. The reset is done
according to the DT characteristics.
For a detailed description of the timer characteristics, see the "General
function block features" section in this manual.
Instantaneous high stage
In addition to the stabilized low stage, 87L has an instantaneous high stage. The stabilizing
is not done with the instantaneous high stage. The instantaneous high stage trips
immediately when the differential current amplitude is higher than the set value of the
High trip value setting. If the ENA_MULT_HS input is active, the High trip value setting
is internally multiplied by the High Op value Mult setting.
I_DIFF
(from Differential calculation)
ENA_MULT_HS
High trip value
High trip value Mult
PROT_ACTIVE
(from Fail safe function)
GUID-64B2FA70-1FCC-44D8-83EC-73EA8F880FB4 V1 EN
Figure 233: Operation logic of instantaneous high stage
Direct inter-trip
Direct inter-trip is used to ensure the simultaneous opening of the circuit breakers at both
ends of the protected line when a fault is detected. Both pickup and trip signals are sent to
the remote end via communication. The direct-intertripping of the line differential
protection is included into 87L. The TRIP output is combined to operate the signal from
both stages, local and remote, so that it can be used for the direct inter-trip signal locally.
Charact.
I
AND
ENABLE OPERATION
1MAC059074-MB A
OPR_HS_LOC
615 series ANSI
Technical Manual