Functions
2.1 General
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
38
The assignment of the protection functions to the ground current inputs in special connections is set out in the
following table.
The settings for address 251 are only possible with DIGSI under Additional Settings.
Note
The settings under address 251 CT Connect. affect the time overcurrent protection with regard to the eval-
uation of phase currents only if address 250 50/51 2-ph prot has been set to OFF.
ATEX100 (Power System)
Parameter 235 ATEX100 enables meeting the requirements for protecting explosion-protected motors for
thermal replicas. Set this parameter to YES to save all thermal replicas of the 7SJ61 devices in the event of a
power supply failure. After the supply voltage is restored, the thermal replicas will resume operation using the
stored values. Set the parameter to NO, to reset the calculated overtemperature values of all thermal replicas
to zero if the power supply fails.
Nominal Values of Current Transformers (CTs)
At addresses 204 CT PRIMARY and 205 CT SECONDARY information is entered regarding the primary and
secondary ampere ratings of the current transformers. It is important to ensure that the rated secondary current
of the current transformer matches the rated current of the device, otherwise the device will calculate incorrect
primary data. At addresses 217 Ignd-CT PRIM and 218 Ignd-CT SEC, information is entered regarding the
primary and secondary ampere rating of the current transformer. In case of a normal connection (starpoint
current connected to I
G
transformer), 217 Ignd-CT PRIM and 204 CT PRIMARY must be set to the same
value.
If the device features a sensitive ground current input, parameter 218 Ignd-CT SEC is set to 1 A by default.
In this case, the setting cannot be changed.
If address 251 has been set so that ground currents are measured by two inputs (setting options A,G2,C,G;
G->B or A,G2,C,G; G2->B), you have to set the primary rated current of the second ground transformer con-
nected to I
N2
at address 238. secondary ampere rating must conform with the phase current transformer.
To calculated the phase current I
B
correctly, the primary rated current of the ground current transformer, which
is used to calculate I
B
(address 217 or address 238), must be smaller than the primary rated current of the
phase current transformer (address 204).
Trip and Close Command Duration (Breaker)
In address 210 the minimum trip command duration TMin TRIP CMD is set. This setting applies to all protec-
tion functions that can initiate tripping.
In address 211 the maximum close command duration TMax CLOSE CMD is set. It applies to the integrated
reclosing function. It must be set long enough to ensure that the circuit breaker has securely closed. An exces-
sive duration causes no problem since the closing command is interrupted in the event another trip is initiated
by a protection function.
Current Input function
I
N2
Time Overcurrent Protection Ground (Chapter 2.2)
I
N
or I
N sensitive
Ground Fault Detection (sensitive / neutral - Chapter 2.9)
Single-phase Time Overcurrent Protection (Chapter 2.4)
Intermittent Ground Fault Protection (Chapter 2.10)
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