explanation leak inductance calculation alstom ca
TRANSCRIPT
© ABB Group April 19, 2023 | Slide 1
Leak InductanceExplanation – your ref J1065
Pontus Sundqvist, Senior enginner 2012-08-22
Content
General information about leakage inductance
Calculation of leakage inductance our ref 12Q1686204
© ABB Group April 19, 2023 | Slide 2
Order Data Sheet
This is only applicable to coarse/fine connection
IEC 60214-02 Tap-Changer Application Guide
Normal Switching Conditions
Small L
Only one loop connected
Normal Switching Conditions
Small L
Only one loop connected
Continued operation
All loops in fine winding connected
Large L
All loops from both coarse and fine winding connected
Switching Conditions at Mid Point (Coarse/Fine)
Critical breaking, going from coarse to fine.
Critical breaking, going from fine to coarse winding
Fine
Coarse
Continued operation at mid point
Switching Conditions at Mid Point (Coarse/Fine)
Leak Inductance
The leak inductance can be :
Calculated with simple calculation (Only for radiell placed
windings)
Calculated with FEM program (ABB) (radiell or axiell placed
windings)
Required Indata for FEM Calculations
I1
N1
t12 t2t1
I2
N2
DW2
DW1
DW3
I3
N3
I4
N4
t23
For accurate estimates of the reactance a FEM calculation must be done
© ABB Group April 19, 2023 | Slide 11
Coarse- fine LV- fine Coarse- LV
FEM Calculation Axial Windings, part 1
HV
Coarse
Fine
LV
HV
© ABB Group April 19, 2023 | Slide 12
LV- HV Coarse- HVFine - HV
FEM Calculation Axial Windings, part 2
Further Calculations
© ABB Group April 19, 2023 | Slide 13
Coarse- fine LV- fine Coarse- LV LV- HV Coarse- HVFine - HV
Results from field calculation used in further calculation to establish severity at breaking
© ABB Group April 19, 2023 | Slide 14
Determination of the recovery voltage
i2ci i1ci
ugci
Hg breaking Rf closing Rg breaking Hf closing
Calculation of leakage inductance our ref 12Q1686204
© ABB Group April 19, 2023 | Slide 15
This window was drawn in ABB FEM program
Window of one phase in FEM program
© ABB Group April 19, 2023 | Slide 16
Made following assumptions:
HV = 883 turns
Coarse 91 turns
Fine 84 turns.
Result:
Recovery voltage appox 6 kV more than 10 times above our limits.
6 kV equals approx 18mH
Result
© ABB Group April 19, 2023 | Slide 17
Recovery voltage appox 6 kV more than 10 times above our limits.
6 kV equals approx 18mH.
In ordering data mentioned 2.15 mH compared to my calculated 18 mH.
18 mH is a normal value for axiell disposed windings (can be from approx 5 mH and higher)
For radiell disposed windings the leakage inductance normal is not higher than 5 mH.
Why such big difference?
Some transformer manufactures use the formula mentioned in a book written ny a competitor to ABB which looks like this:
© ABB Group April 19, 2023 | Slide 18
This fomula is only valid radiell disposed windings not axiell.
This could explain the big difference, I don´t know.
© ABB Group April 19, 2023 | Slide 19