ABB RELION REX640 Technical Manual page 1280

Section 7
Condition monitoring functions
1274
For a star-delta transformer, it is recommended to use the function on
the star winding, since the circulating zero sequence currents (in case
of unbalance) cannot be measured on the delta winding of the
transformer.
Transformer parameter selection
The transformer parameters are selected based on the Parameter Sel method, Cooling
mode, Transformer type, and Transformer rating settings.
If the Parameter Sel method setting is set to "IEC", the transformer parameters' values
are automatically selected as per the IEC 60076-7 guidelines based on
Table 1200: Constants based IEC guidelines
Cooling mode
Oil Exponent (x)
Winding Exponent (y)
Constant K11 (k )
11
Constant K21 (k )
21
Constant K22 (k )
22
Oil Time Constant (Շ )
0
[minutes]
Winding Tm Constant (Շ )
w
[minutes]
If Parameter Sel method is set to "IEEE", the constants are selected as per the IEEE
C57.91™-2011 standard based on
Table 1201: Constants based on IEEE guidelines
Cooling mode
Oil Exponent (x)
Winding Exponent (y)
Constant K11 (k )
11
Constant K21 (k )
21
Constant K22 (k )
22
Oil Time Constant (Շ )
0
[minutes]
Winding Tm Constant (Շ )
w
[minutes]
Distribution Transformers Medium and Large power transformers
ONAN ONAN
0.8 0.8
1.6 1.3
1.00 0.50
1.00 2.00
2.00 2.00
180 210
4 10
Table 1201.
Distribution Transformers Medium and Large power transformers
ONAN ONAN
0.8 0.8
0.8 0.8
1.00 1.00
1.00 1.00
1.00 1.00
180 210
4 10
1MRS759142 C
Table 1200.
ONAF OFAF ODAF
0.8 1.0 1.0
1.3 1.3 2.0
0.50 1.00 1.00
2.00 1.30 1.00
2.00 1.00 1.00
150 90 90
7 7 7
ONAF OFAF ODAF
0.8 0.8 1.0
0.9 0.9 1.0
1.00 1.00 1.00
1.00 1.00 1.00
1.00 1.00 1.00
150 90 90
7 7 7
REX640
Technical Manual