ABB RED615 Technical Manual page 369

1YHT530004D05 D
615 series
Technical Manual
GUID-010E1FF3-D7B0-42C8-9179-09F753D7DFC3 V1 EN
Figure 189: Operation logic of the fail safe function
The function can also be set into "test/blocked" state with the Operation setting.
This can also be utilized during the commissioning.
The BLOCK input is provided for blocking the function with the logic. When the
function is blocked, the monitored data and measured values are still available but
the binary outputs are blocked. When the function is blocked, the direct inter-trip is
also blocked.
The PROT_ACTIVE output is always active when the protection function is
capable of operating. PROT_ACTIVE can be used as a blocking signal for backup
protection functions.
Timer
Once activated, the timer activates the STR_LS_LOC output. Depending on the
value of the set Operating curve type, the timer characteristics are according to DT
or IDMT. When the operation timer has reached the value set with the Operate
delay time in the DT mode or the maximum value defined by the inverse time
curve, the OPR_LS_LOC output is activated. When the operation mode is
according to IDMT, Low operate value is used as reference value (Start 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, LNPLDF has an instantaneous high stage.
The stabilizing is not done with the instantaneous high stage. The instantaneous
Section 4
Protection functions
363