Application of isolation transformers for paper machine DC drives-a service perspective

Summary form only given. Personal experience related to multiple paper-machine sectional drives grouped on one isolation transformer are presented. It is argued that, in such cases, from a service viewpoint, isolation transformers should be applied individually to every DC drive. This supplies the maximum isolation for the drive from interference caused by another drive. Based on experience, drives rated higher than 50 kW perform satisfactorily when grouped on isolation transformers. Armature-reversing DC drives with a maximum capacity rating of less than 50 kW perform much better with their own isolation. The author´s experience has shown that the problem is related more to the drive rating than the motor size. Individual isolation is required for small drives.<>