M. Pühringer, Trench Austria - AT - Session 2 - Block 1- Question 3.3 page 1 Barcelona May 2003 RESONANT GROUNDING versus LOW IMPEDANCE GROUNDING

M. Pühringer, Trench Austria - AT - Session 2 - Block 1- Question 3.3 page 2 Barcelona May 2003 Resonant grounding is also applied in: Scandinavia numerous Central European countries Eastern Europe Neutral point treatment in Germany * * VDEW Störungsstatistik 1998 Neutral Point Treatment Application Survey

M. Pühringer, Trench Austria - AT - Session 2 - Block 1- Question 3.3 page 3 Barcelona May 2003 E Voltages during earth fault N L1L1 L3L3 L2L2 V 3E V 0 = V 1N ILIL ICIC I2I2 I3I3 V 2E V 2N V 3N L 1 =E Resonant Grounding Basics - Theory I res / I C undercompensation overcompensation d

M. Pühringer, Trench Austria - AT - Session 2 - Block 1- Question 3.3 page 4 Barcelona May 2003 Arc Suppression Coil (ASC) Earth Fault Compensation Controller Earth Fault Detection EPSY - Earth fault Protection SYstem System Components

M. Pühringer, Trench Austria - AT - Session 2 - Block 1- Question 3.3 page 5 Barcelona May 2003 Resonant grounding  self-extinction by the ASC  no influence on power supply % transient faults % steady faults  low fault current - increased human safety - reduced damage - reduced interference - reduced earthing effort quality of power supply increased Low impedance grounding - high fault current (e.g. 2 kA) - immediate tripping high number of power interruptions Resonant Grounding Comparison 100 % Earthfaults