Motor Repair/Replace Decisions
From Imrtwiki
The group discussed in detail the reliability in-service experience of different types of motors from different suppliers as well as supplier’s delivery and service performance. The information discussed is best viewed from the comparison matrix filled out by the attendee organizations. Also a good overview of attendee’s motor supplier preferences is included in Appendix 1 point 9 by Albert Lo from Sydney Water.
Sydney Water indicated that they use a simple software program to determine if repair of a removed motor was viable or if replacement was the best solution. Rio Tinto indicated that they replace removed motors with a new drives in the range from 20kW to 55kW. If a smaller motor is unique in some way that makes it harder to replace, this rule may not apply. Ricky from Northparkes indicated that sometimes smaller drives are rewound rather than replaced due to long delivery times for new motors.
Peter from OneSteel suggested that when ordering new drives it is important to ensure you specify the motor terminal box position. They had a tight situation where the terminal box was on the wrong side and would not fit. He indicated similar situations can occur with flange mounted motors when the specific alignment of the motor frame to the bolt hole pattern is not fully specified.
Another problem discussed is where a motor is replace and the physically identical frame size and installation arrangement is not available or desirable. One issue that has affected both Rio Tinto and Hunter Water was the need to convert an Australian frame size to replace the equivalent American frame size. Richard from Rio Tinto indicated that they had an Australian frame drilled to the American Bolt hole specification by the CMG during manufacture. Another solution used, especially where a large older style frame size is replaced by a more modern smaller frame size, is to use an adaptor spacer frame.
Noel from Blue Circle raised the problem he has faced with replacing failed motors on small SEW type motor gearbox sets that are typically ordered by project or mechanical personnel with no involvement of electrical personnel. The solution suggested by Noel is as these combination units are low cost the whole motor gearbox should be replaced if the motor fails.
