Evaluating Logic (See Figure 2.2); Indication, Signalling And Test; Figure 2.2 Evaluating Logic And Signalling - Siemens 7SN71 Instruction Manual

Transient earth-fault relay 7SN71
2.2

Evaluating logic (see figure 2.2)

Once the set current and voltage memories have
been released and evaluated
1
the directional indication are set and the correspon
ding relay/LED is activated
Reset
J
+
&
+
V
J
-
&
V -
1
"Release"
6
Continous
earth fault
Figure 2.2 Evaluating logic and signalling
2.3

Indication, signalling and test

The indication and signalling for the direction of a
transient earth fault are stored and are therefore not
set anew upon further occurence of a transient earth-
fault. Indication and and signalling for the continuous
earth-fault" are not stored. i.e. are discontinued upon
disappearance of the displacement voltage (cf. also
sections 2.4 and 2.5).
Siemens AG March 1997
Instruction Manual
, the memories for
2
. The respective relay or
3
2
S
R
S
R
S7
1
w
&
Method of operation
Order No.: E50410-A0007-U501-A1-7691
LED is also activated
nal indication and continuous earth-fault
sed.
3
forward
H1 K1
reverse
H2 K2
5
Continuous earth fault
H3 K3
The green LED (Operation") indicates the readiness
(auxiliary voltage) of the device. An alarm signal is
output in the event of an auxiliary voltage supply fai
lure.
The test buttons for forward and reverse direction are
used to test the analog evaluation, the evaluating lo
gic, the LEDs and the alarm relays.
, once the signals for directio
6
are relea
5
3B4
Transient earth-fault
3B1
forward direction
3B2
L+
3A1
3B3
Transient earth-fault
3A2
reverse direction
4A1
Continuous earth
fault
4A2
2
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