In addition to meeting and exceeding the U.S. Department of Energy efficiency standards, the single- and three-phase 5kVA – 500kVA “ULTRA-K Series 600K-he” models provide electrical noise attenuation and transient voltage suppression to protect sensitive electronic loads from disruption or failure. Each model is offered with four different K-factor ratings (K4, K7, K13, K20) for full compatibility with the harmonic-rich currents associated with non-linear loads.