2.12 Instantaneous high-current switch-on-to-fault protection (SOTF)
225
7SA522 Manual
C53000-G1176-C155-3
Figure 2-97 Logic diagram of the high current switch on to fault protection
2.12.2 Setting Notes
Requirement A prerequisite for the operation of the switch-onto-fault protection is that in address
627)2YHUFXUU = (QDEOHG was set during the configuration of the device
scope of functions. At address )&7627)2& it can also be switched 21 or
2)).
Pickup Threshold The magnitude of the current which causes pick-up of the switch onto fault function is
set as ,!!! in address . The setting value should be selected large enough to
ensure that the protection under no circumstances picks up due to an overload condi-
tion or due to a current increase resulting from e.g. an automatic reclosure dead time
on a parallel feeder. It is recommended to set at least 2.5 times the rated current of the
feeder.
2.12.3 Settings
The table indicates region-specific presettings. Column C (configuration) indicates the
corresponding secondary nominal current of the current transformer.
Addr. Parameter C Setting Options Default Setting Comments
2401 FCT SOTF-O/C ON
OFF
ON Inst. High Speed SOTF-O/C
is
2404 I>>> 1A 1.00 .. 25.00 A 2.50 A I>>> Pickup
5A 5.00 .. 125.00 A 12.50 A
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