ABB Relion 670 Series Applications Manual page 534

Section 18
Monitoring
According to IEEE C57.109.1993 standard, single phase transformers above 10 MVA and three
phase transformers above 30 MVA come under category IV transformers. The recommended
protection curve for category IV transformer is given in
applied as a protection curve for all faults, frequent and in-frequent. The curve is dependents
upon the transformer short circuit impedance for fault currents above 50% of the maximum
possible and it leads to worst case mechanical duty with maximum fault current for 2s. The
damage intensity from through faults depends on the current magnitude, fault duration, and
the total number of fault occurrences. Refer to
function settings values corresponding to the given transformer.
Table 86: Transformer nameplate data
Parameter
Frequency
Rated Power
Voltage ratio
Winding 1 rated current
Winding 2 rated current
Winding 3 rated current
Tap changer
Connection Type YNyn0d1
Cooling
% Impedance
According to the IEEE standard and
be calculated with respect to transformer % impedance 12. In this case,
based on the maximum allowable fault current 800 % of rated current for 2s duration. Also, if
the transformer manufacturer indicates that 10 such through faults can be withstand over the
life time of the transformer, then the cumulative
Table 87:
Setting parameter
W1I>
W2I>
W3I>
tMin
MaxI2tW1
MaxI2tW2
MaxI2tW3
MaxI2tCmlW1
MaxI2tCmlW2
MaxI2tCmlW3
528
PTRSTHR setting parameters
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Figure
Table 86 for the through fault monitoring
Value
50 Hz
500 MVA / 500 MVA / 20 MVA
415 kV / 230 kV / 20 kV
696 A
1255 A
577 A
±9; 1.67% of 230 kV
YNyn0d1
ONAF
12 @ Base 500 MVA
Figure 251, the given transformer withstand capability can
2
I t limits can be set accordingly.
Select value
350 % IBaseW1
350 % IBaseW2
350 % IBaseW3
0.2 s
 
 2
696 8
 
1000000
IECEQUATION18025 V1 EN-US
 
 2
1255 8
1000000
IECEQUATION18051 V1 EN-US
 
 2
577 8
 
1000000
IECEQUATION18052 V1 EN-US
 
62.0 10 620 kA s
IECEQUATION18053 V1 EN-US

201.608 10 2016.08 kA s
IECEQUATION18054 V1 EN-US

42.615 10 426.15 kA s
IECEQUATION18055 V1 EN-US
1MRK 511 401-UEN Rev. K
251. This curve should be
2
I t limits are calculated
 
2
2 62.0 kA s
 
  2
2 201.608 kA s
 
2
2 45.615 kA s
 
2
 
 2
 
2

Bay control REC670
Application manual