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Example 3.
Biased differential relay SPAD 330 C used for
the winding short-circuit and interturn fault
protection of a YNyn0 connected power
12
B
P1
P2
S1
S2
Setting of the matching of the power transformer
vector group:
With the adjacent setting the access of the
earth fault current flowing in the primary
circuit through the power transformer
neutral is prevented from entering the
energizing circuits of the differential relay.
transformer, when the current transformers
have "outside" earthings, i.e. the current
transformers have the basic connection type I.
P2
S2
Switch
1
2
3
4
5
6
P1
L1
L2
L3
S1
SG1
0
1
0
1
0
0
∑ = 10
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