Diagrams - Siemens 7PG21 Solkor Rf Technical Manual

R a
A
+
-
+
O
-
W D5
A
O
W
Figure 14 Single End Fed fault Rf mode, positive half cycle
A
D1
-
O
+
-
+
W
R a
W
O
A
Figure 15 Single End Fed fault Rf mode, negative half cycle
The single end fed internal fault conditions configure the circuit in a similar way to the double end fed internal fault
but only one summation transformer has any output. Thus the other summation transformer acts only as an
equalising transformer, re-circulating current through the measuring element as indicated in Figure 14 & Figure
15. The voltage distribution shows diagrammatically how, in each half cycle, the measuring elements are
energised via R at the energised end and the action of the remote end summation transformer re-circulating
a
current via the polarising diodes D4 on one half-cycle and D8 on the other half-cycle.
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R p
B
C
D3 D4
Y
R p
X
B
C
Y
X
C
B
R p
D7
D8
X Y
R p
X
Y
C
B
7PG21 Solkor Rf Description of Operation
R
a D
P
R a
R a
P
Z
R a
Chapter 1 Page 12 of 13
Z
D
P
Z
D
Z
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