Grounding Considerations in Cogeneration

Increased interest and activity in cogeneration for industrial facilities has alerted engineers to many ramifications on the subject of grounding practices. When the utility is the sole source of power, decisions for grounding will usually be made on long-standing traditional practices. Also when self-generation is completely independent of the utility, the user may elect a unique procedure for grounding. However, if both systems may be occasionally tied together, a contingency must be allowed for such a combination. Harmonic generation, particularly of the third order and its odd multiples, can be troublesome. Ground fault limitations are imposed by physical limitations of generators. The location and type of ground source must be reconsidered, especially for multiple generators. These and other considerations are addressed, and some specific recommendations are made aimed at maximum continuity and preventing problems.