ORNL, Oak Ridge, Tennessee, USA
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory has been operating for over 15 years and many electronic components are now obsolete and require replacement to assure reliability and sustainability. SNS uses stepper motors to control accelerator components throughout the facility including the cryomodule tuners, beam scrapers, and the primary and secondary stripper foils. The original motor controls were implemented with VME controllers, custom power supplies, and various types of motor drivers. As these components became less reliable and obsolete a new control solution was needed that could be applied to multiple motion control systems. Fast performance requirements are not crucial for these stepper motors, so the PLC technology was selected. The first system replaced was the Ring stripper foil control system and plans are underway to replace the beam scrapers. This paper provides an overview of the commercial off-the-shelf (COTS) hardware used to control stepper motors at SNS. Details of the design and challenges to convert a control system during short maintenance periods without disrupting beam operation will be covered in this paper.
