ABB SACE Tmax XT2 User Manual page 58

D Protection Function
D Protection is very similar to S protection plus the ability to recognize current direction during
the malfunction period.
The direction of the current allows detecting if the malfunction is upstream or downstream of the
device controlled by Ekip Touch.
In ring distribution systems, D protection makes it possible to identify the distribution section
where the malfunction occurred and to isolate it without affecting the rest of the system (using
zone selectivity).
Depending on the direction of the malfunction, if the current of one or more phases exceeds the
I7 threshold (fw or bw) for a time greater than t7 (fw or bw), the protection is activated and sends
the TRIP command.
The direction of the malfunction is determined by comparing the direction of the malfunction
current detected with the direction of reference.
Sequence of
phases set
123
123
123
123
321
321
321
321
To verify and simulate the trip times based on all the parameters, see:


Parameters
Parameter
Enable
Trip Enable
Threshold I7
Fw
Threshold I7
Bw
Time t7 Fw
Time t7 Bw
1SDH002031A1002 ECN000092998
NOTE: the direction of reference is calculated by considering the value set for the
power flow direction and the phase sequence (cyclical direction of the phases):
Power flow set
High  Low
Low  High
High  Low
Low  High
High  Low
Low  High
High  Low
Low  High
Protection summary table with the formulas for calculations (page 79)
Chart with tripping curve (page 91)
Description
Enables/disables protection and availability on menu of the parameters
Activates/deactivates the open command: if disabled, the alarm and the
lapsing of the protection time are managed only as information
Defines the value that activates the protection in the event of a forward
direction.
The value is expressed both as an absolute value (Ampere) and as a
relative value (In), settable in a range: 0.6 In .. 10In with 0.1 In step
Defines the value that activates the protection in the event of backward
direction.
The value is expressed both as an absolute value (Ampere) and as a
relative value (In), settable in a range: 0.6 In .. 10In with 0.1 In step
This is the intervention time in the event of a forward direction.
The value is expressed in seconds, which are settable in a range:
0.1 s .. 0.8 s, with 0.01 s step
This is the trip time in a backward direction.
The value is expressed in seconds, settable in a range:
0.1 s .. 0.8 s, with 0.01 s step
Rev. B
Sequence of Reference direction
phases detected (forward direction)
High  Low
123
Low  High
123
Low  High
321
High  Low
321
Low  High
123
High  Low
123
High  Low
321
Low  High
321
SACE Tmax XT2 – XT4 | 58
Default
OFF
ON
2 In
2 In
0.2 s
0.2 s