MODEL FOR TRANSFORMERS WINDINGS FOR LIGHTNING

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MODEL FOR TRANSFORMERS WINDINGS FOR LIGHTNING

• CREDSON DE SALLES
• MANUEL LUÍS BARREIRA MARTINEZ

HIGH VOLTAGE LABORATORY FEDERAL UNIVERSITY OF
ITAJUBÁ
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? TO DISCUSS THE EVALUATION OF LIGHTINING
IMPULSE OSCILLOGRAMS
OBJECTIVES
- SMALL NOISES ORIGINS
? SMALL FAILURES MAY NOT BE NOTICED
- RECORDING EQUIPMENT, CABLING SCALING
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? ATP PREVIOUS KNOWLEDGE OF THE FAILURE MODE
SIMULATIONS
? MODEL PARAMETERS
I - CAPACITANCES TO GROUND WINDING TO WINDING
CAPACITANCES ? SCHERING BRIDGE II WINDING
SELF CAPACITANCE IMPULSE INDUCTANCE ?
LIGHTNING IMPULSE TEST.
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SIMULATIONS

• SWITCHES MODELING SHORT CIRCUITS
• ? RCC SHORT-CIRCUIT RESISTANCE

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SIMULATIONS
? EVALUATION OF THE IMPULSE INDUCTANCE
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SIMULATIONS
? EVALUATION OF THE SELF CAPACITANCE
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SIMULATIONS
? MODEL ATTACHEMENT
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FAILURE SIMULATIONS
? Curve differences Internal construction Actua
l? Pancake ? Model? Continuous Winding
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FAILURE SIMULATIONS
CHOPPED IMPULSES
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TIME SCALING EFFECT
10 kVA 150 kV SINGLE PHASE TRANSFORMER
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AMPLITUDE SCALING EFFECT
75 kVA 150 kV THREE PHASE TRANSFORMER
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FINAL COMMENTS

• THE MODEL PRESENTS A REASONABLE ATTACHMENT WITH
  TESTING.
• ?THE MODEL CAN AND MUST BE IMPROVED.
• ?THIS SIMPLE MODEL, FOR A COMPLEX PROBLEM, IS
  ABLE TO SHOW THAT SIGNALS ADDRESSED TO HIGH
  FREQUENCY OSCILLATIONS COUPLING EFFECT COULD
  MEAN FAILURES.
• ? THERE ARE PROBLEMS WITH TIME AMPLITUDE
  SCALING THAT CAN HIDE SOME FAILURE EVIDENCES.