Hitachi Relion 670 Series Applications Manual page 61

1MRK506375-UEN Rev. N
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.
4.2.4 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-earth voltage from the VT.
4.2.4.1 Example
Consider a VT with the following data:
110 kV 100
/
2
IECEQUATION16054 V1 EN-US
The following setting should be used: VTprim=110 (value in kV) VTsec=100 (value in V)
4.2.4.2 Examples how to connect, configure and set VT inputs for most
commonly used VT connections
Figure 18
+
U
Pri
IEC06000591 V1 EN-US
Figure 18:
Where:
a)
b)
c)
d)
It shall be noted that depending on national standard and utility practices the rated secondary voltage
of a VT has typically one of the following values:
• 100 V
• 110 V
The IED fully supports all of these values and most of them will be shown in the following examples.
Railway application RER670
Application manual
V
2
defines the marking of voltage transformer terminals commonly used around the world.
+
A
(H1)
U
Sec
N
(H2)
a)
Commonly used markings of VT terminals
is the symbol and terminal marking used in this document. Terminals marked with a square indicate the
primary and secondary winding terminals with the same (positive) polarity
is the equivalent symbol and terminal marking used by IEC (ANSI) standard for phase-to-earth connected
VTs
is the equivalent symbol and terminal marking used by IEC (ANSI) standard for open delta connected VTs
is the equivalent symbol and terminal marking used by IEC (ANSI) standard for phase-to-phase connected
VTs
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a
A
(X1) (H1)
n N
(H2)
(X2)
b) c)
da
A
(X1)
(X1)
(H1)
dn
B
(H2)
(X2) (X2)
d)
en06000591.vsd
Section 4
Analog inputs
SEMOD55055-44 v4
SEMOD55055-47 v3
(Equation 1)
SEMOD55055-60 v6
a
b
55