Ferroresonant overvoltages in grounded wye-wye padmount transformers with low-loss silicon steel cores

Reduced no-load losses have resulted in increased susceptibility to ferroresonance of grounded wye-wye three-phase distribution transformers using five-leg silicon steel wound cores. The authors describe the results of an extensive test program which determined that overvoltages are directly related to the ratio of capacitive susceptance divided by core losses and that the conventional use of rated exciting current can be a misleading indicator of ferroresonance susceptibility.<>