Elta STDL500-3EC-R Twinflow Centrifugal Box Fan Three Phase EC - 500mm (rectangular spigots)

The Elta STDL500-3EC-R is a Twinflow duty/standby centrifugal box fan for 500mm duct systems, with rectangular spigots sized 498 x 598mm. Two backward curved fans sit side by side in one acoustically lined case: one runs, the other waits on standby. At full speed it moves up to 6264 m³/h free air, about 5760 m³/h at 100 Pa, and still delivers 3373 m³/h against 500 Pa.Each fan has an IP44 EC external rotor motor (380 to 480V three phase, 50/60Hz) with sealed for life bearings, and the case is 1.2mm galvanised mild steel. An auto changeover panel (149-ACO3/BDV) is fitted as standard, switching to the standby fan if the duty fan fails and sharing run hours between the two. Speed is set by the built in commissioning potentiometer or a 0-10V signal, and Elta give a 12 month (1 year) manufacturer warranty. 3 Phase EC Motor Up to 6264 m³/h Speed Controllable What it is best used forThe biggest Twinflow in the range, on a 380 to 480V three phase supply: warehousing, factories, industrial units, large kitchens (general ventilation) and big office or college systems on 500mm ducting. It moves 6264 m³/h free air, about 5256 m³/h at 200 Pa and still 3373 m³/h at 500 Pa.It needs a three phase supply and 132 kg of structural support. If you only have single phase, the STDL500-1EC is the alternative, with about 1753 m³/h at 500 Pa. Not for corrosive, explosive or above +60°C air.Why choose this over alternativesThe point of a twin fan is resilience. A single fan such as the Elta SSDL500-3EC-R Singleflow moves more air in the same duct size (6552 m³/h free air against 6264 m³/h here, and 4320 m³/h at 500 Pa against 3373 m³/h), but when its motor fails the extract stops until someone replaces it. The STDL500-3EC-R keeps running on its standby fan, the panel gives a normally open fail contact for a BMS or alarm, and the duty share means neither motor does all the hours. Choose it for windowless toilets, risers and any system where a dead fan means a complaint or a breach of the venti