What is the difference between DCS built-in sequence of events recorder (SER) & stand alone SER?

 

SER is a valuable tool in troubleshooting plant shutdowns. However, the resolution of the SER messages is a crucial factor. A stand-alone SER, typically, has 1 msec resolution.

When SER is implemented in DCS, the scan time is the resolution. This can run into several hundred milli seconds. SER with a resolution of say 100 msec. won't be of much use. Some DCS vendors provide contact input modules that have built-in Sequence Of Events capability. The time stamping, with 1 msec. resolution, is done at the module itself. With this type of set up, usually a dedicated SOE server is required.

There are many TMR systems that have the SOE option built into the input modules. To name a few - ICS Trusted, GE Speedtronic Mark VI/VIe, etc. The resolution is 1 msec.

 

Thanks a lot.

 

Most of the DCS vendors now a days provided SOE with stamp time of 1 millisecond. same is the case with SER. There are both plus and minus of using stand alone SER.

First thing if you use stand alone SER then u have wire up all the contacts upto SER card through all sort of fuses. If the fuse of SER is blown off u will never know until and unless the alarm is configured as alarm to open and the engineer checks SER daily. But in DCS/PLC the SOE picks data directly from the input card used for process control. So any failure of fuse is immidiatly notified to operator as process disturbance and he can get it rectified immidiatly.

On the other hand DCS/PLC will show SER only of the tags hooked up. e.g. Boiler DCS/PLC will show SER for Boilers only not for Balance of plant. To get that points in DCS SER you have to hook all those points to DCS/PLC which involves huge financial cost and added burden on the controller.

Still i will go for the SOE inbuilt in the DCS/PLC coz it makes ur life very easy while analysing any trip. Single fuse blown in case of stand alone SER can give you sleeples nights. Just imagine the turbine tripped on the same parameters whose fuse has blown off along with two other tripping parameters. Keep breaking ur heads and keep guessing...

On Dec 19, 2007 11:10 pm, Anurag Rathi wrote:
What is the difference between DCS built-in sequence of events recorder (SER) & stand alone SER?

( Complete thread: http://www.control.com/thread/1026242265 )