Pulse Width Modulated inverter design with IGBT technology. "Off line" operation for increased reliability and efficiency. 50ms transfer time. Self-testing/self-diagnostic operation. 97% efficiency rating at full load. Harmonic distortion <10%. Load power factor range .5 lead to .5 lag. 1.5 KVA to 16.7 KVA models. Compatible with all fluorescent, incandescent and LED lighting loads. Backup generator compatible.