... -start 3.relay alarm output 4.Speed contro brushless exterior rotor motor ec axial fan 630mm (500,560,630,710,800mm )available ... -temperature protection features 5.loss phase protection 6.the locked motor protection 7.Reverse function 8.online model 9.Regulate speed ... Noise testing room:Waterspray test iquipment: brushless exterior rotor motor ec axial fan 630mm