Siemens SIPROTEC 7UT613 series Manual page 168

2 Functions
Table 2-8 Preferred values of standard currents for user-defined dropout characteristics
I/I
= 1 to 0.86
p
1.00 0.93
0.99 0.92
0.98 0.91
0.97 0.90
0.96 0.89
0.95 0.88
0.94 0.86
Inrush Restraint
Additional Overcur-
rent Protection
Functions for
Phase Currents
168
For specification of a dropout characteristic please note the following:
• For currents select the values from table 2-8 and add the corresponding time
values. Deviating values I/I
• Currents greater than the current value of the largest characteristic point do not lead
to a prolongation of the dropout time. The dropout characteristic (see Figure 2-76,
left side) goes parallel to the current axis, up to the largest characteristic point.
• Currents smaller than the current value of the smallest characteristic point do not
lead to a reduction of the dropout time. The dropout characteristic (see Figure 2-76,
left side) goes parallel to the current axis, beginning with the smallest characteristic
point.
• Currents smaller than 0.05 · times the setting value of currents lead to an immediate
dropout.
I/I
= 0.84 to 0.67
p
0.84 0.75
0.83 0.73
0.81 0.72
0.80 0.70
0.78 0.69
0.77 0.67
At address 2002 InRushRest. Ph of the general settings, the inrush restraint can
be enabled (ON) or disabled (OFF). Especially for transformers and if overcurrent time
protection is used on the supply side, this inrush restraint is required. Function param-
eters of the inrush restraint are set in „Inrush".
The inrush restraint is based on an evaluation of the 2nd harmonic present in the
inrush current. The ratio of 2nd harmonics to the fundamental component 2.HARM.
Phase (address 2041) is set to I
without being changed. To provide more restraint in exceptional cases, where ener-
gising conditions are particularly unfavourable, a smaller value can be set in the afore-
mentioned address.
If the current exceeds the value indicated in address 2042 or 2043 I Max InRr.
Ph., no restraint will be provoked by the 2nd harmonic.
The inrush restraint can be extended by the so-called "crossblock" function. This
means that on harmonic content overshoot in only one phase, all three phases of the
stage are blocked. At address 2044 CROSS BLK.Phase the crossblock func-
I> or
p
tion is set to YES or to NO.
The time period for which the crossblock function is active after detection of inrushes
is set in address 2045 T CROSS BLK.Ph.
In the aforementioned description, the first overcurrent protection for phase currents
is described respectively. The differences in the parameter addresses and message
numbers of the first, second and third overcurrent protection are illustrated in the fol-
lowing table. The positions marked by x are identical.
are rounded. This, however, will not be indicated.
p
I/I
= 0.66 to 0.38
p
0.66 0.53
0.64 0.50
0.63 0.47
0.61 0.44
0.59 0.41
0.56 0.38
/I = 15 % as default setting. It can be used
2fN fN
I/I
= 0.34 to 0.00
p
0.34 0.16
0.31 0.13
0.28 0.09
0.25 0.06
0.22 0.03
0.19 0.00
7UT613/63x Manual
C53000-G1176-C160-2