Manual Checking of Servo


Thread Starter



Need a detailed reply of manual checking of Electro hydraulic servo valves of gas splitter valve. Recently our frame tripped due to Split valve problem, after that we changed the valve for that. but how we check the servo valve working correctly before the unit startup?

is there any way to do this through Mark v system HMI<I>?

and in trip log I saw one header with the name DROP NUMBER. what is the use of that number?

kindly reply folks..
thanks and regards

The topic of verifying the polarity of the current being applied to servo-valve coils has been covered many times before on

There is a 'Search' field cleverly hidden at the far right of the Menu Bar at the top of ever desktop webpage; the 'Search' function is accessed from the '' drop-down on the Menu Bar of the mobile versions of It is suggested you use the Search 'Help' before searching for topics; it's not like your probable preferred Internet search engine.

Also, don't be afraid to use several different search terms, including:

+"servo-valve polarity"

+"polarity check"

+"servo polarity"

(the plus sign and double quotes are BIG hints!)

Drop Number refers to the Drop Number assigned to Process- and Diagnostic Alarms in Mark V and prior turbine control systems. It's a way of tracking alarms through the documentation. With Mark V, you can use the Process Alarm Drop Number from the Alarm on the HMI or printer (you do use the Alarm Printer, right?) and cross-reference it using ALARM.LST, an ASCII text file in the F:\UNIT1 directory, to find the name of the logic signal which is associated with the Process Alarm. Diagnostic Alarm Drop Numbers are similarly useful when trying to troubleshoot Diagnostic Alarms, to a degree....