1SDH002031A1002 ECN000092998 Rev. B SACE Tmax XT2 – XT4 | 52
Function
Like the S(V) protection, the S2(V) Protection protects against short circuits, with a threshold
sensitive to the voltage value.
It is independent of S(V) protection and it is therefore possible to program thresholds and
functions of the two protections to take advantage of different system solutions (example:
signaling with S(V) and opening command with S2(V) or vice versa, or S(V) and S2(V) both for
signaling or for tripping).
If the current of one or more phases exceeds the I21 threshold for a time greater than t21, the
protection is activated and sends the TRIP command.
Following a voltage drop, the I21 threshold varies according to two different modes:
Scal (step) provides a step variation based on the parameters Ul2 and Ks2.
Lin (linear) provides a dynamic variation based on the parameters Ul2, Uh2, and Ks2.
To verify and simulate the trip times based on all the parameters, see:
Protection summary table with the formulas for calculations (page 79)
Chart with tripping curve (page 89)
Parameters
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
Enables the operating mode Scal or Lin to be selected:
Defines the value that activates protection and contributes to
calculating trip time.
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 voltage determines the change of the trip threshold 121, with different
behaviour according to the selected mode:
The value is expressed both as an absolute value (Volt) and as a relative
value (Un), settable in a range: 0.2 Un .. 1 Un with 0.01 Un step
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