For the last equation, the condition t1 > tMin shall also be fulfilled. This practically
means that tMin will be equal to the set t1 value when absolute voltage deviation
DA is equal to ΔU ( relative voltage deviation D is equal to 1). For other values see
figure 125. It should be noted that operating times, shown in the figure 125 are for
30, 60, 90, 120, 150 & 180 seconds settings for t1 and 10 seconds for tMin.
t1=180
t1=150
t1=120
t1=90
t1=60
t1=30
IEC06000488_2_en.vsd
IEC06000488 V2 EN-US
Figure 125: Inverse time characteristic for TR1ATCC and TR8ATCC
The second time delay, t2, will be used for consecutive commands (commands in
the same direction as the first command). It can have a definite or inverse time
characteristic according to the setting t2Use (Constant/Inverse). Inverse time
characteristic for the second time delay follows the similar formulas as for the first
time delay, but the t2 setting is used instead of t1.
Line voltage drop
SEMOD159053-105 v6
The purpose with the line voltage drop compensation is to control the voltage, not
at the power transformer low voltage side, but at a point closer to the load point.
Figure
126 shows the vector diagram for a line modelled as a series impedance
with the voltage U
B
at the L
V busbar and voltage U
L
at the load center. The load
current on the line is I
L
, the line resistance and reactance from the station busbar to
the load point are R
L
and X
L
. The angle between the busbar voltage and the
current, is j. If all these parameters are known U
L
can be obtained by simple
vector calculation.
Values for R
L
and X
L
are given as settings in primary system ohms. If more than
one line is connected to the LV busbar, an equivalent impedance should be
calculated and given as a parameter setting.
Section 12 1MRK 506 375-UEN A
Control
294 Railway application RER670 2.2 IEC
Application manual
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