ActronAir Indoor Evaporator EC Plug Fan and Impeller 630mm 3-Phase is a large-diameter EC variable-speed plug fan for high-capacity Hercules and Tri-Capacity commercial ducted systems, where the 630mm impeller delivers the very high airflow volumes required by large commercial coil configurations at variable speed via 0-10V signal from the indoor PCB. A failed EC plug fan on a Hercules unit causes immediate loss of all indoor airflow and rapid system shutdown on high-discharge temperature protection -- this is a critical system component that warrants priority replacement. Isolate power at mains before replacement -- EC motors and variable drives retain dangerous residual voltages for up to 5 minutes after power isolation.