Zipernowsky, with Bláthy and Déri, experimented with power supplies. They researched how to transport distances with minimal loss. By their subsequent investigations, the ZBD alternating current transformer is presented in 1885. The ZBD system is based on the appliance utilization by parallel closed iron core with an arbitrary ratio and operating by alternating current. The ZBD system converts high primary voltage to smaller, "service" voltages (Stepping down the energy). Nikola Tesla creates the voltage increasing transformers for the power transmission lines used wordwide and provides energy to the ZBD systems.