Reid & Mitchell (R&M) has established three clean rooms for the winding of stators in its Benoni workshop to prevent contamination during the winding process, thereby improving their integrity when they resume operation after being repaired.
“A controlled environment such as this minimises the risk of insulation faults occurring in the stators, as it keeps chemicals, moisture and dust particles out of the winding process, so greatly reducing the chances of failure due to contamination,” explained Rene Rajzman, R&M’s Operations Executive.
Rene and his colleagues designed, constructed and installed the clean rooms entirely in-house at R&M. The clean rooms, enclosed by thick transparent plastic sheeting on all four sides and the top, are each 15m2 in area and 2.2m high.
“They’re each equipped with a purpose-designed winding table that automatically turns the stator to facilitate the winding, which is performed by two winding operators, who wear special laboratory suits for the purpose,” Rene pointed out.
“The end-side wall of the clean room closest to the winding table is temporarily removed by hand to permit entry of the stator for winding, while the room itself is mounted on trolly wheels running on rails so that it can be rolled out of the way to enable the stator to be installed onto the winding table from an overhead crane. The enclosure is then rolled back into place and the removeable wall re-installed. Access for the working personnel is gained via a door at the other end of the room. The cleanliness of the room is maintained through the supply of a controlled volume of air, which blows all contaminants out at floor level, while the positive air pressure in the room prevents their entry.”
The prototype first clean room was installed and commenced operation in November last year and the other two were installed in May this year. “Now, with all three rooms and winding tables in place, we are able to keep pace with the demand with all the stator windings we are required to perform in the contaminant-free conditions we’ve established for this purpose,” Rene commented.
All of the AC stator windings and some of the DC armature windings at the workshop are now done in this way.
“By establishing these clean rooms we have taken a further step in applying R&M’s longstanding policy of continuous improvement,” Rene concluded.