ABB Relion 670 Series Technical Reference Manual page 116

Section 4
Basic IED functions
110
If SMAI setting ConnectionType is Ph-Ph at least two of the inputs GRPx_A, GRPx_B
and GRPx_C must be connected in order to calculate positive sequence voltage. If
SMAI setting ConnectionType is Ph-N, all three inputs GRPx_A, GRPx_B and
GRPx_C must be connected in order to calculate positive sequence voltage.
If only one phase-phase voltage is available and SMAI setting ConnectionType is Ph-
Ph the user is advised to connect two (not three) of the inputs GRPx_A, GRPx_B and
GRPx_C to the same voltage input as shown in figure
positive sequence voltage (that is input voltage/√3).
IEC10000060 V1 EN
Figure 38: Connection example
The above described scenario does not work if SMAI setting
ConnectionType is Ph-N. If only one phase-ground voltage is available,
the same type of connection can be used but the SMAI ConnectionType
setting must still be Ph-Ph and this has to be accounted for when
setting IntBlockLevel. If SMAI setting ConnectionType is Ph-N and the
same voltage is connected to all three SMAI inputs, the positive
sequence voltage will be zero and the frequency functions will not
work properly.
The outputs from the above configured SMAI block shall only be used
for Overfrequency protection (SAPTOF, 81), Underfrequency
protection (SAPTUF, 81) and Rate-of-change frequency protection
(SAPFRC, 81) due to that all other information except frequency and
positive sequence voltage might be wrongly calculated.
1MRK505222-UUS C
38 to make SMAI calculating a
IEC10000060-1-en.vsd
Technical reference manual