Preventing Circulating Current in Parallel Generator Applications

As the need for secure and reliable electricity has gown, many opportunities for distributed generation have appeared. Diesel, Natural Gas, Biofuel or other generators used for these applications often run in parallel with themselves or with Utility transformers. This can result in high levels of triple frequency (180Hz in 60Hz systems) circulating current in the common neutrals or ground connections. These circulating currents can cause overheating in the generator windings and false tripping of overcurrent protection devices, especially ground fault schemes.

Mirus’ GenLink Dissimilar Pitch Neutral Limiter (DPNL) is a uniquely wound, multiple coil reactor which can be very effective in blocking the flow of circulating current without negatively impacting system fault levels.

MIRUS’ President & CEO, Tony Hoevenaars P.Eng, covered how paralleling generators can lead to very high neutral circulating currents and what can be done to control them. The problem is particularly evident when the generators are built with dissimilar pitches but is also very common when generators are paralleled with Utility transformers for Distributed Generation.

In this webinar, attendees learned:

Understanding Generator Pitch and Harmonics
How Circulating Current Problems Start
Effective Method for Reducing Circulating Current
Adding Circulating Path Impedance without Effecting Ground Fault Path
Sizing Neutral Blocking Solution for Specific Applications
Real-World Case Studies