8.15 DIESEL PLANT OPERATION
When diesel alternator sets are put in parallel, “hunting” or “phase swing may be produced due
to resonance unless due care is taken in the design and manufacture of the sets. This condition occurs
due to resonance between the periodic disturbing forces of the engine and natural frequency of the
system. The engine forces result from uneven turning moment on the engine crank which are corrected
by the flywheel effect. “Hunting” results from the tendency of each set trying to pull the other into
synchronism and is characterized by flickering of lights.