ABB Relion 670 series, Руководство по применению

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CTs involved in the protection scheme. The rated CT primary current value is set as parameter
CTPrim under the IED TRM settings.
For all other protection applications (e.g. generator, shunt reactor, shunt capacitor and
transformer protection) it is typically desirable to set
IBase parameter equal to the rated
current of the protected object. However this is only recommended to do if the rated current
of the protected object is within the range of 40% to 120% of the selected CT rated primary
current. If for any reason (e.g. high maximum short circuit current) the rated current of the
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 v3
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 v2
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 v5
Figure 19 defines the marking of voltage transformer terminals commonly used around the
world.
Section 4 1MRK 505 343-UEN B
Analog inputs
74
Application manual