Customised motor solves test chamber problems

With help from a motor supplier, a manufacturer of environmental test chambers has managed to re-locate the fan-driving motors outside the chambers, writes Dean Palmer Extreme temperatures and high humidity levels are not normally the best environments for AC induction motors. But these issues can be overcome if the motor manufacturer is prepared to customise the motor to meet the required climatic conditions. Temperature Applied Sciences (TAS) is a manufacturer of environmental test chambers based in Goring-by-Sea. These chambers are used in many applications, including industrial manufacturing, pharmaceuticals and clean rooms. Customers of test chambers use them for climatic shock, burn-in processes, storage and product endurance testing, from R&D work through to end-of-line batch testing. Conditions inside the chambers range from -80°C to 180°C and 98% humidity at 95°C, with chamber size varying from microwave size up to enclosures large enough for earthmoving equipment. Because of these extreme chamber conditions, TAS needed to locate the fan-driving motors outside and attach the fans on extended shafts. Originally, the company tried fixing extensions to standard shafts, which was fine when the fans were located in the ceiling of the chambers with the shafts at the vertical. However, when located in the chamber walls, there was shaft distortion, excessive bearing wear and shaft run out, as well as problems with supply. These issues have now been resolved using customised AC induction motors from AEG Electric Motors. AEG supplied a customised AM 71 frame single phase motor, which has a 400mm long, 14mm diameter stainless steel shaft and modified bearings to cope with the loadings resulting from the fan impellers being located at the end of the elongated shafts. The motors are used to drive fans with blade diameters from 150mm to 300mm and are controlled via a fully integrated control system that ensures climatic conditions are accurately maintained. Director at TAS, Martin Stevens commented: "The AEG motors have resolved both our technical difficulties and supply problems. As a result, we are adopting another size of motor [56 frame] with extended shaft for our smaller climatic chambers."