Just got called out to chinese takeaway. Main extract fan not working. Its single phase and runs off a transformer with 5 speed settings. The fan is 240v and the markings have rubbed off but draws around 4-5 amps maybe around 1000w or a bit more. Its inside ducting about two ft square. I do houses in the main so this is new to me. The fan windings hum very loud when switched on and anything over setting 2 blows the 8amp transformer fuse within a second or so. There is a cylinder that look likes it could be a large capacitor. Could it be this or is it just blown windings ? I've bypassed the transformer but it still produces the same hum and no spin. Your best thoughts appreciated.