ABB XT7, Руководство по эксплуатации и обслуживанию

Страница: 50 / 193

ABB | SACE Tmax XT
48 | © 2020 ABB | 1SDH001821A1002 - ECN000135670 Protections | 7 - Standard Protections
G Protection
G
I4
t
t4
I
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
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)
• the graph with trip curve (page 97)
Parameters
Parameter Description Default
Enable
Activates/deactivates the protection and its availability in the
parameters menu.
OFF
Trip Enable
Activates/deactivates transmission of the open command. if disabled,
the alarm and exceedance of protection time are only managed as
information.
ON
Curve
Establishes curve dynamics and the threshold or trip time calculation:
• t = k: fixed time trip
• t = k/I
2
: inverse time-delay dynamic trip
t = k
Threshold I4
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
0,2 In
Time t4
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)
0,4 s
Prealarm I4
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
90 % I4
ZoneSelectivity
Activates/deactivates the function and selectivity time availability on
the display (page 75)
NOTE : the function is only available with curve t = k
OFF
Selectivity time
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
0,04 s
StartUp enable
Activates/deactivates the function and availability of the associated
parameters on the display (page 78)
OFF
StartUp
Threshold
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
0,2 In
StartUp Time
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
0.1 s
Continued on the next page