Toro EHC-01-04 4 Station Normally Open Electric Hydraulic Converter. Toro® Electric-Hydraulic Converters (EHC) provide the ability to bring together electrical outputs from sophisticated electric controllers and the pressure based signals in hydraulic irrigation systems. EHC is ideal for retrofitting hydraulic systems, enabling NormallyOpen (NO) or Normally-Closed (NC) hydraulic valves to be operated with a 24 VAC output irrigation system controller. For new installations, hydraulic control valves are ideal for applications in areas with increased lightning risk. What’s more, you can add as many converters as you need – expansion is unlimited.