Siemens SIPROTEC easy 7SJ45 Handbuch Seite 54

Manual 7SJ45
chanical relays. In case several faults occur successively it is en-
sured that the "prehistory" is taken into consideration due to the
inertia of the disk and that the time behavior is matched. The
7SJ45 divides the operation range of the disk emulation into an
incrementing zone (1.1 to 20
⋅
(< 0,9 I/I ). The zone in between is called idle state zone since
P
this is the zone where the virtual disk is in idle state.
The current transformer supply of 7SJ45 conditions that the de-
vice is unable to operate with single-phase supply and currents
⋅
smaller than 0.8 I . The device and the virtual disk are reset.
N
The operation zones of the reset characteristics therefore de-
pend on the setting value selected for I
tions. If, for instance, I = 4.0 is selected, the disk emulation (with
P
single-phase supply and I/I
When the disk emulation is picked up again, the time counter
starts at zero.
If you press the "ENTER" key, the disk emulation will also be
reset.
The disk emulation offers its advantages when the grading coor-
dination chart of the time overcurrent protection is combined (on
electromechanical base) with other devices connected to the sys-
tem.
C53000-K1174-C001-7
⋅
I/I ) and a decrementing zone
P
and the supply condi-
P
= 0.2) is reset due to a device reset.
P
The current thresholds relating to the rated device current are set
on the device. These thresholds include:
Current transformer I / I
NP NS
Rated device current I
N
Maximum load current
Safety factor (assumed)
120A
------------- -
Ip
=
100A
All parameters are set on an additive basis. Some parameters
have fixed upper and lower thresholds.
,
Setting value
100 A / 5 A
5 A
120 A
1.25
I
NS
⋅ ⋅ , , ⋅
.
.
------- - 1
25 1 5 I
=
N
I
N
å
,
=
Switch values
Settings
54