All AxZent fans have new optimized and high efficient HD impellers with backward curved blades, manufactured from aluminium. The AxZent 630E4 are equipped with IEC standard motors outside the air stream, controllable only via frequency converter!. In addition to that all three phase AxZent DV models are 400V D/Y connectable for two speed operation. Motor protection by thermal contact to be connected to an external motor protection device. The long casing is manufactured from pre-galvanized steel and has spun flanges according Eurovent 1/2, for direct installation in duct systems. Please note: Speed control by voltage, i.e. voltage transformers, is not possible!