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)