About the 12M9-0021-A6
Functioning as a module bay for the MM300 series, the 12M9-0021-A6 is designed and produced by General Electric Multilin. The MM300 series is a highly scalable unit, and partially accomplishes this through its use of modules that make up the necessary core elements and also expanded optional functions of the relay. As a result, users can swap out modules when they require a system upgrade or when modules need repair or replacement. The reduction of loose parts makes repair quicker and users can more immediately identify which module system issues stem from.
Modules are also quite easy to remove, with detailed instructions and diagrams included in the MM300 user manuals; one of which can be found on the AX Control website. Modules are held in place by two captive screws at the bottom and top of the module, which can be removed with a standard flat-blade screwdriver. Modules can then be unlatched and slid out of their position in the case. Users should first remove control power to the MM300 unit, lest user injury occur.
The modules housed by the module bay perform a variety of functions for the relay, ranging from supplying power to the unit (power supply module) to offering digital inputs and voltage input (IO_C) to RTDs (IO_G). Modules must be replaced with like modules, or replaced in the correct location if there is no existing module. For example, Slot D can only house the IO_A module while slot C can house the IO_C module or the IO_E module. As can be seen, IO lettering does not necessarily indicate the appropriate slot for installation, so users should carefully review their manual before making major changes to their module bay.
