ABB RELION REX640 Technical Manual page 1385

1MRS759142 F
K
I_A, I_B and I_C
I
rated
Transformer type is set to "Single phase", the denominator consists only of I
If
instead of 3×I
Equation 321
considered.
Transformer parameter selection
The transformer parameters are selected based on the
Cooling mode , Transformer type , and Transformer rating settings.
If the
values are automatically selected as per the IEC 60076-7 guidelines based on
1323
Table 1323: Constants based IEC guidelines
Cooling mode
Oil Exponent (x)
Winding Exponent (y) 1.6
Constant K11 (k
Constant K21 (k
Constant K22 (k
Oil Time Constant
(Շ
0
Winding Tm Constant
(Շ
w
Parameter Sel method is set to "IEEE", the constants are selected as per the IEEE
If
C57.91
Table 1324: Constants based on IEEE guidelines
Cooling mode
Oil Exponent (x)
Winding Exponent (y) 0.8
Constant K11 (k
Table continues on the next page
REX640
Technical Manual
Load factor
RMS value of input phase currents (Amperes)
Rated current (Amperes)
2
.
rated
assumes that voltage is constant and tap changer position is not
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.
Parameter Sel method setting is set to "IEC", the transformer parameters'
.
Distribution
Transformers
ONAN
0.8
) 1.00
11
) 1.00
21
) 2.00
22
180
) [minutes]
4
) [minutes]
™
-2011 standard based on
Distribution
Transformers
ONAN
0.8
) 1.00
11
Condition monitoring functions
Medium and Large power transformers
ONAN ONAF
0.8 0.8
1.3 1.3
0.50 0.50
2.00 2.00
2.00 2.00
210 150
10 7
Table 1324
.
Medium and Large power transformers
ONAN ONAF
0.8 0.8
0.8 0.9
1.00 1.00
Parameter Sel method ,
OFAF ODAF
1.0 1.0
1.3 2.0
1.00 1.00
1.30 1.00
1.00 1.00
90 90
7 7
OFAF ODAF
0.8 1.0
0.9 1.0
1.00 1.00
2
rated
Table
1385