How the PM866(Primary Controller) controller recognizes that there is a fault in the first cluster.
I am in Rectifier plant.We have ABB 800 xA SCADA system in our plant.
Problem:Our Load Shedding (primary )Controller got faulty and control switch overed to redundant controller.
In system alarms we got message "RPA ,RPB,Modulebus Clustermodem error"
and then waring on primary unit RPA,Error on backup unit RPA,RPB,Redundant mode enabled,unit B Acts Primary."
How can we resolve this?
Rearding the question:How the PM866(Primary Controller) controller recognizes that there is a fault in the first cluster?
AC800M-Redundant controller(1:1) has designed in such a way that Always one acting as Primary that will control the process & other acting as a backup(hot-stand by),The stand by controller take over the processs bumplessly in less than 10ms when ever the fault occured in the primary controller.
In your case: Since you are using redudant controller with TB840 has the optical-modem, here each TB840 are connected to each controller (generally upper Tb840 to upper CPU & lower TB840 to lower CPU) so in this case only one TB840 is in line always so whenever there is a problem in TB840 either power fail/optical cable removal/moduel error occurs at this perticuler running module at that time running controller which is acting as primary controller will go to fault to cause control switch over to standby controller & at the same time TB840 has also switched over to standby.
So you are getting system alarms corresponding to error occured in the module.
Regarding RPA,RPB: AC800M has the fecility to supervise the reulatory power supoply(A & B) so here in you case you may be missed the wiring you should connect A power supply to SA(Supervision A) to both controllers & SB(supervision B) to both controllers
If you won't wire these pins you will et these messages always in system alarm & perticuler controller system status viewer that you can see in the control str.
OR may be both power supply failed that's why you are getting alarm in system alarm list.
Please refer the drawing for how to do the wirin for SA & SB