current Ι
B
is determined by phase currents Ι
A
and Ι
C
as well as the measured ground current Ι
N2
at the second
current input. The setting must be set according to system requirements.
The assignment of the protection functions to the ground current inputs in special connections is set out in
the following table.
Current Input Function
Ι
N2
Time overcurrent protection ground (Section 2.2 Overcurrent Protection 50, 51, 50N,
51N)
Directional time overcurrent protection ground (Section 2.3 Directional Overcurrent
Protection 67, 67N)
Important!
The function “Directional time overcurrent protection ground” may only be operated if
the ground current of the protected line is measured via Ι
N2
. This is not the case for the
example shown in Figure 2-4. Here, the ground current of the protected line is meas-
ured via Ι
N
. The function must be deactivated. A connection in which the function can
be enabled is illustrated in C Connection Examples Figure C-5.
Ι
N
or Ι
Nsdlich
Ground fault detection (sensitive / not sensitive) (Section 2.13 Ground Fault Protection
64, 67N(s), 50N(s), 51N(s))
Single-phase time overcurrent protection (Section 2.5 Single-Phase Overcurrent Protec-
tion)
Intermittent ground fault protection (Section 2.14 Intermittent Ground Fault Protec-
tion)
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
evaluation of phase currents only if address 250 50/51 2-ph prot has been set to OFF.
Voltage Connection (Power System)
Address 213 determines how the voltage transformers are connected.
VT Connect. 3ph = Van, Vbn, Vcn means that three phase voltages are wye-connected.
VT Connect. 3ph = Vab, Vbc, VGnd means that two phase-to-phase voltages (open delta voltage) and
V
N
are connected. The latter setting also has to be selected when only two phase-to-phase voltage trans-
formers are used or when only the displacement voltage (zero sequence voltage) is connected to the device.
Vab, Vbc, Vx if two phase-to-phase voltages (open-delta connection) and any third voltage V
x
are
connected. Vx is used exclusively for the flexible protection functions. The transformer nominal voltages for V
x
are set at address 207 and 208. This connection type is not available for the devices 7SJ621 and 7SJ622.
The devices 7SJ623, 7SJ624, 7SJ625, 7SJ626 and 7SJ64 contain 4 voltage measuring inputs which enable
further options in addition to the above-mentioned connection types.
VT Connect. 3ph = Van,Vbn,Vcn,VGn is selected if the three phase voltages in wye-connection and V
N
are connected to the fourth voltage input of the device.
Select VT Connect. 3ph = Van,Vbn,Vcn,VSy in case the fourth voltage input is used for the synchroniza-
tion function. This is recommended even if two phase-to-phase voltages (open delta voltage) are available on
the primary side (because the voltages are connected to the device in such a way that the device measures
phase-ground voltages under symmetrical conditions).
Van,Vbn,Vcn,Vx is selected if in addition to the three phase voltages any fourth voltage V
x
is connected. Vx
is used exclusively for the flexible protection functions. The transformer nominal voltages for V
x
are set at
address 207 and 208.
Parameter 240 VT Connect. 1ph is set to specify that only one voltage transformer is connected to the
devices. In this case, the setting defines which primary voltage is connected to which analog input. If one of
Functions
2.1 General
SIPROTEC 4, 7SJ62/64, Manual 43
C53000-G1140-C207-8, Edition 08.2016
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