Power quality analysis and corrections

The paper discusses the effect of short circuit fault on sensitive loads and methods for reducing the duration of voltage sags, swells or interruptions by improving existing protection methods or adding advanced protection schemes. Requirements for the recording of power quality events in order to understand their effects on the manufacturing process are presented. Combining multiple overcurrent elements in a complex overcurrent characteristic, using negative sequence overcurrent protection, distribution bus and breaker failure protection, fuse saving or selective backup tripping schemes are described.