ABB RET670 Applications Manual page 56

Section 3
IED application
50
Where:
1) shows how to connect single-phase CT input in the IED.
2) is TRM where these current inputs are located. It shall be noted that for all these current
inputs the following setting values shall be entered.
For connection (a) shown in figure 13:
CT prim = 1000 A
CT sec = 1A
CTWyePoint = ToObject
For connection (b) shown in figure 13:
CT prim = 1000 A
CT sec = 1A
CTWyePoint = FromObject
3) shows the connection made in SMT tool, which connect this CT input to the fourth input
channel of the preprocessing function block 4).
4) is a Preprocessing block that has the task to digitally filter the connected analog inputs and
calculate values. The calculated values are then available for all built-in protection and
control functions within the IED, which are connected to this preprocessing function block.
If frequency tracking and compensation is required (this feature is typically required only for
IEDs installed in the power plants) then the setting parameters
accordingly.
Setting of voltage channels
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-ground voltage from the VT.
Example
Consider a VT with the following data:
132kV 120V
3 3
EQUATION1937 V1 EN
The following setting should be used: VTprim=132 (value in kV) VTsec=120 (value in
V)
Examples how to connect, configure and set VT inputs for most
commonly used VT connections
Figure 14 defines the marking of voltage transformer terminals commonly used around
the world.
1MRK504116-UUS C
DFTReference shall be set
(Equation 16)
Application manual