Siemens SIPROTEC 7UT613 series Manual page 391

7UT613/63x Manual
C53000-G1176-C160-2
To obtain the actual pickup value, the set value has to be multiplied with the vector
group factor k and the following equation:
VG
The following table shows these changes as a factor k
group and the type of fault, for three-phase transformers.
Table 3-26 Correction Factor k
Type of Fault Reference Winding
(high voltage)
3-phase
2-phase
single-phase
with I elimination
0
single-phase
without I elimination
0
Example:
three-phase transformer
Vector Group
Rated voltage
(high-voltage winding)
Current Transformer
Rated voltage
(high-voltage winding)
Current Transformer
The following applies to the high voltage winding:
In this case the rated current of the winding is practically equal to the current trans-
former rated current. Thus, the pickup value (referred to the rated relay current) com-
plies with the setting value I-DIFF> of the device (k
single-phase testing with zero sequence current elimination, a pickup value 1.5 times
higher must be expected.
The following applies to the low voltage winding:
When testing this winding, the pickup value (referred to the rated device current) will
amount to
Because of the odd vector group numeral, the following pickup values apply (Table )
depending on vector group and fault type
VG
even VG numeral
(0, 2, 4, 6, 8, 10)
1
1
3/2 = 1,5 3/2 = 1,5
1
S = 57 MVA
N
Yd5
U = 110 kV
N
300 A/1 A
U = 25 kV
N
1500 A / 1 A
3.3 Commissioning
depending on the vector
VG
uneven VG numeral
(1, 3, 5, 7, 9, 11)
1 1
√3/2 ≈ 0,866
1
√3 ≈ 1,73
1
= 1 for reference winding). For
VG
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