ABB REB670 Series - Setting of voltage channels; Example; Examples how to connect, configure and set VT inputs for most commonly used VT connections

protected object is less than 40% of the rated CT primary current, it is strongly recommended
to set the parameter IBase in the IED to be equal to the largest rated CT primary current
among all CTs involved in the protection scheme and installed on the same voltage level. This
will effectively make the protection scheme less sensitive; however, such measures are
necessary in order to avoid possible problems with loss of the measurement accuracy in the
IED.
Regardless of the applied relationship between the IBase parameter and the rated CT primary
current, the corresponding minimum pickup of the function on the CT secondary side must
always be verified. It is strongly recommended that the minimum pickup of any instantaneous
protection function (e.g. differential, restricted earth fault, distance, instantaneous
overcurrent, etc.) shall under no circumstances be less than 4% of the used IED CT input rating
(i.e. 1A or 5A). This corresponds to 40mA secondary for IED 1A rated inputs and to 200mA
secondary for IED 5A rated inputs used by the function. This shall be individually verified for all
current inputs involved in the protection scheme.
Note that exceptions from the above 4% rule may be acceptable for very special applications
(e.g. when Multipurpose filter SMAIHPAC is involved in the protection scheme).
4.2.4 Setting of voltage channels
SEMOD55055-44 v4
As the IED uses primary system quantities, the main VT ratios must be known to the IED. This
is done by setting the two parameters
VTsec and VTprim for each voltage channel. The phase-
to-phase value can be used even if each channel is connected to a phase-to-earth voltage from
the VT.
4.2.4.1 Example
SEMOD55055-47 v3
Consider a VT with the following data:
132 110
3 3
kV V
EQUATION2016 V1 EN-US (Equation 1)
The following setting should be used: VTprim=132 (value in kV) VTsec=110 (value in V)
4.2.4.2 Examples how to connect, configure and set VT inputs for most
commonly used VT connections
SEMOD55055-60 v6
Figure
26 defines the marking of voltage transformer terminals commonly used around the
world.
A
(H1)
B
(H2)
b
(X2)
a
(X1)
A
(H1)
N
(H2)
n
(X2)
a
(X1)
b) c)
A
(H1)
N
(H2)
dn
(X2)
da
(X1)
d)
U
Pri
+
+
U
Sec
a)
en06000591.vsd
IEC06000591 V1 EN-US
Figure 26: Commonly used markings of VT terminals
Section 4 1MRK 505 370-UEN D
Analog inputs
74 Busbar protection REB670
Application manual