EQUATION1951 V1 EN-US (Equation 54)
EQUATION1952 V1 EN-US (Equation 55)
The residual power is a complex quantity. The protection will have a maximum sensitivity in
the characteristic angle RCA. The apparent residual power component in the characteristic
angle, measured by the protection, can be written:
0 A ,prot 0 A 0 A
S 3U 3I cos
j
= × ×
EQUATION1953 V1 EN-US (Equation 56)
0 B,prot 0 B 0 B
S 3U 3I cos
j
= × ×
EQUATION1954 V1 EN-US (Equation 57)
The angles φ
A
and φ
B
are the phase angles between the residual current and the residual
voltage in the station compensated with the characteristic angle RCA.
The protection will use the power components in the characteristic angle direction for
measurement, and as base for the inverse time delay.
The inverse time delay is defined as:
0 0
inv
0 0
kSN (3I 3U cos (reference))
t
3I 3U cos (measured)
× × × j
=
× × j
EQUATION1942 V2 EN-US (Equation 58)
The function can be set
On/Off
with the setting of
Operation
.
Common base IED values for primary current (IBase), primary voltage (UBase) and primary
power (SBase) are set in a Global base values for settings function GBASVAL.
GlobalBaseSel
: It is used to select a GBASVAL function for reference of base values.
RotResU
: It is a setting for rotating the polarizing quantity ( 3U
0
) by 0 or 180 degrees. This
parameter is set to 180 degrees by default in order to inverse the residual voltage ( 3U
0
) to
calculate the reference voltage (-3U
0
e
-jRCADir
). Since the reference voltage is used as the
polarizing quantity for directionality, it is important to set this parameter correctly.
With the setting
OpMode
the principle of directional function is chosen.
With
OpMode
set to
3I0cosfi
the current component in the direction equal to the characteristic
angle
RCADir
has the maximum sensitivity. The characteristic for
RCADir
is equal to 0° is shown
in Figure 65.
Section 7 1MRK 511 358-UEN A
Current protection
138
Application manual
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