Modbus Concentrator is a protocol translator that converts the GE commnet protocol to Modbus RTU open protocol. It’s typically found in GE AKD switchgear or Spectra Series switchboards. It allows the integration of Microversa trip units.
The Modbus concentrator has since been obsoleted by GE. If you have switchgear with a failed Modbus concentrator, the recommended solution is to replace the trip unit with AC-PRO trip unit. It can be retrofit to the GE switchgear and it has Modbus communications.