ABB SACE Tmax XT7 Operation And Maintenance Manual page 50

G Protection
t
I4
48 | © 2020 ABB | 1SDH001821A1002 - ECN000135670
Function
Ekip Touch calculates the vector sum of the phase currents (L1, L2, L3, Ne) and obtains the internal earth
fault current (Ig): if current Ig exceeds threshold I4, the protection trips and, after a time established by the
G
value read and by the parameter settings, transmits the TRIP command.
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 87)
t4
• the graph with trip curve (page 97)
Parameters
I
Parameter
Enable
Trip Enable
Curve
Threshold I4
Time t4
Prealarm I4
ZoneSelectivity
Selectivity time
StartUp enable
StartUp
Threshold
StartUp Time
Description
Activates/deactivates the protection and its availability in the
parameters menu.
Activates/deactivates transmission of the open command. if disabled,
the alarm and exceedance of protection time are only managed as
information.
Establishes curve dynamics and the threshold or trip time calculation:
• t = k: fixed time trip
• t = k/I : inverse time-delay dynamic trip
2
Establishes the value that activates the protection and contributes
towards calculating the trip time.
The value is given as both absolute value (A) and relative value (In) and
can be set within the range: 0.1 In to 1 In, in 0.001 In steps
It is the trip time or contributes towards timing calculation, depending
on the type of curve selected.
The value is given in seconds and can be set within the range: 0.1 s to
1 s, in 0.05 s steps
NOTE: in the presence of curve: t = k, t4 can also be configured
as: instantaneous; in this mode, the trip time is comparable to
that given for I protection (page 87)
Warns that the measured current is near to the protection activation
threshold.
The value is given in percentage of threshold I1 and can be set within
the range 50% I4 to 90% I4, in 1% steps.
The prealarm condition deactivates in two cases:
• current lower than prealarm threshold I4
• current higher than threshold I4
Activates/deactivates the function and selectivity time availability on
the display (page 75)
NOTE: the function is only available with curve t = k
This is the trip time of the protection with the zone selectivity function
activated and selectivity input not present (page 75)
The value is given in seconds and can be set within the range: 0.04 s
to 0.2 s, in 0.01 s steps
Activates/deactivates the function and availability of the associated
parameters on the display (page 78)
Protection threshold valid during Startup time, in the conditions in
which the function is activated (page 78)
The value is given as both absolute value (A) and relative value (In) and
can be set within the range: 0.2 In to 1 In, in 0.1 In steps
This is the time for which the StartUp threshold remains activated,
as calculated from the moment the activation Threshold is exceeded
(page 78)
The value is given in seconds and can be set within the range: 0.1 s to
30 s, in 0.01 s steps
ABB | SACE Tmax XT
Default
OFF
ON
t = k
0,2 In
0,4 s
90 % I4
OFF
0,04 s
OFF
0,2 In
0.1 s
Continued on the next page
Protections | 7 - Standard Protections