Page 58 - MCCB-XT2-XT4

ABB | SACE Tmax XT

D Protection Function
D protection is very similar to S protection, with the additional capability of recognizing the direction of
t the current during a fault.
I7 D The current direction allows the user to find out whether the fault is on the supply side or load side of the
t7bw device controlled by Ekip Touch.
t7fw In ring type distribution systems, D protection allows the distribution section in which the fault has
occurred to be identified and disconnected without affecting the rest of the installation (using zone
selectivity).
I
Depending on the direction of the fault, if the current of one or more phases exceeds threshold I7 (I7fw or
I7bw) for longer than time t7 (t7fw or t7bw), the protection activates and sends a TRIP command.
The fault direction is established by comparing the detected fault current with the reference direction.
NOTE: the reference direction is calculated considering the set value of the power flow
direction and the phase sequence (cyclic direction of the phases):
Phase sequence (de- Reference direction
Phase sequence (set) Power flow (set)
tected) (forward direction)
123 High-->Low 123 High-->Low
123 Bottom --> Top 123 Bottom --> Top
123 High-->Low 321 Bottom --> Top
123 Bottom --> Top 321 High-->Low
321 High-->Low 123 Bottom --> Top
321 Bottom --> Top 123 High-->Low
321 High-->Low 321 High-->Low
321 Bottom --> Top 321 Bottom --> Top

To check and simulate the trip times in relation to all the parameters, please consult:
• the summary table of the protections with the calculation formulas (page 75)
• the graph with trip curve (page 89)
Parameter Description Default
Activates/deactivates the protection and its availability in the
Enable OFF
parameters menu
Activates/deactivates transmission of the open command: if disabled,
Trip Enable the alarm and exceedance of protection time are only managed as ON
information
Establishes the value that activates the protection with forward
Threshold I7 direction. 2 In
Fw The value is given as both absolute value (amperes) and relative value
(In) and can be set within the range: 0.6 In to 10 In, in 0.1 In steps
Establishes the value that activates the protection with backward
Threshold i7 direction. 2 In
Bw The value is given as both absolute value (amperes) and relative value
(In) and can be set within the range: 0.6 In to 10 In, in 0.1 In steps
This is the trip time in the case of forward direction.
Time t7 Fw The value is given in seconds and can be set within the range: 0.1 s to 0,2 s
0.8 s, in 0.01 s steps
This is the trip time in the case of backward direction.
Time t7 Bw The value is given in seconds and can be set within the range: 0.1 s to 0,2 s
0.8 s, in 0.01 s steps
Activates/deactivates the function and selectivity time availability on
ZoneSelectivity the display.

(1) NOTE: configure selectivities S, S2, I, 2I, MCR and G OFF to ensure OFF
that selectivity D functions correctly
This is the trip time of the protection with the zone selectivity function
Selectivity activated, forward direction and selectivity input Fw not present. 0,13 s
time Fw (1) The value is given in seconds and can be set within the range: 0.1 s to
0.8 s, in 0.01 s steps
This is the trip time of the protection with the zone selectivity function
Selectivity activated, backward direction and selectivity input Bw not present.
time Bw (1) The value is given in seconds and can be set within the range: 0.1 s to 0,13 s
0.8 s, in 0.01 s steps

Continued on the next page
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