a-eberle REG-DA - Oil Cooling Types; IEC Formula Selection; Fan Assignment Modes

SETUP
Page 23
5.1.1.5 Overview of the IEC standard settings
Distribution transformers
Medium and large power transformers
ONAN
ONAN * limited oil flow
ONAN
ONAF * limited oil flow
ONAF
OFXX * limited oil flow
OFXX
ODXX
Hot spot gradient
Hgr
[K]
23
26
26
26
26
22
22
29
Winding exponent
IEC 60354
y
1,6
1,6
1,6
1,6
1,6
1,6
1,6
2,0
Winding exponent
IEC 60076-7
y
1,6
1,3
1,3
1,3
1,3
1,3
1,3
2,0
Constant IEC 60076-7
k
11
1,0
0,5
0,5
0,5
0,5
1,0
1,0
1,0
Constant IEC 60076-7
k
21
1,0
3,0
2,0
3,0
2,0
1,45
1,3
1,0
Constant IEC 60076-7
k
22
2,0
2,0
2,0
2,0
2,0
1,0
1,0
1,0
Winding time constant
w
[min]
4
10
10
7
7
7
7
7
Table 1: IEC standard settings for monitoring parameters
* The information „limited oil flow“ in the above shown table is related to the oil flow
through the winding. If a winding of an ON or OF cooled transformer is zigzag-cooled, a ra-
dial spacer thickness of less than 3 mm might cause a restricted oil circulation. This fact is
taken into account in the IEC 60076 algorithm.
Constants for the IEC 60076 algorithm
The constants k
11
, k
21
and k
22
for the IEC 60076 algorithm are automatically selected by the
cooling type settings. There is no need to set them manually.