Neutral inversion in power systems

A neutral displacement due to abnormal system conditions (other than short-circuits) is known by the name of ¿neutral in version¿. This can occur as a result of open circuits in one or more phases of systems possessing inductance and capacitance, or owing to special conditions of neutral earth connections. A general formula is developed for the position of the neutral point on any system of any number of phases, balanced or unbalanced. This is then applied to deduce the neutral displacements occurring as a result of open circuits on systems fitted with neutral-earthing transformers and Petersen coils or arcing-earth suppressors. The possibility of neutral inversion on certain types of balanced system, even without open circuits, is demonstrated and a qualitative consideration of the phenomena is given. Finally, instances are mentioned of neutral inversion which has occurred in practice, and remedies are indicated, together with a summary of system arrangements to be avoided in design.