IEEE C37.081a:1997 (R2007)

Amendment Standard - Inactive-Reserved.
The transient recovery voltage needs to be modified when interrupting asymmetrical currents. The voltage rate R, the peak voltage E2 and the rate of change of current di/dt all change with the asymmetrical current zero. Guidance is provided on how to make these corrections when compared to the symmetrical case.

This revision will provide information on how to determine the Transient Recovery Voltage wave shapes for asymmetric terminal faults. The basis of rating is given and the factors to be applied for various fault conditions, i.e., degree of asymmetry and time of interruption.
Add ratings for asymmetric faults to existing standard. This represents work that has been done to develop the ratings.