We have 3 GE Frame 9E machines and last week 2 of them were tripped with following sequence & alarms.

GT86A001C, CTG1C lockout relay operated.
EHGCBG001C, CTG1C generator breaker opened.
GT1C RESET CTG1C reset signal from MKV Old = ON New = OFF
GT1CTRIP, CTG1C tripped signal from Mark V
GT1CONS CTG1C stopped
1CL30EX CTG1C EX2000 General alarm
1CL30EXSS CTG1C Exciter alarm
1CL30EXTRPFL CTG1C EX2000 trip fault.
1CBURN1 ~ 4TRIP, All four burners tripped.
1CL30EXALM, CTG1C EX2000 diagnostic alarm
1CL86TGTALM, CTG1C generator differential trip.
1CL86HD CTG1C Hydraulic protection trip.

Following alarms appeared on MKV.
1-Generator protection trip.
2- Generator breaker tripped.
3- EX2K trip.
4-EX2K diagnostic alarm.
At EX2000 software following fault alarm appeared
16 NORMOPEN normally open interlock is closed.
379 UCP_WDOG DCP / UCC watchdog time out.
Note: AT MKV EX2000 screen different fault alarms appeared than EX2000 software which are 378 & 15 (
Generator differential lock out (86 A) also operated.

The alarms were reset by rebooting the EX2000 and machine was started. The similar trips have occurred in past and always reset by rebooting the EX2000.

Can anybody explain the reason of this trip & preventive measures for avoiding in future.

 

It's almost impossible to analyse a trip without being able to personally examine a copy of the Alarm Logger printout from the trip. Speedtronic turbine control systems can annunciate several different trip conditions when a turbine is tripped, as the list provided shows, but it's critical to see the timestamps of the alarms and the order in which they were annunciated in order to be able to see which one occurred first.

A <b>LOT</b> of people think the last alarm on the printout (in effect, at the "top" of the list of alarms) is the cause of the trip. But, that's quite often not the case because several trip conditions can be detected and annunciated after the one that actually initiated the trip (isn't this fun?).

A <b>LOT</b> of people also confuse SOEs and EVENTs with alarms, and Speedtronic operator interfaces do not always print alarms and events in chronological order. The timestamps may be correct, but the order they are sent to the printer is not always chronologically correct. So, it's necessary to look at the printout and manually, visually sort the list to see what actually tripped the turbine, if that can be determined.

Many times when an electrical protective relay trips the 86 lockout relay which trips the turbine, the exciter doesn't get a signal to stop (shutdown) at exactly the proper time and actually trips itself on over voltage or over current. It's kind of a "relay race" sometimes and can be very misleading.

From the watchdog reference, it would seem that a Mark VI or Mark VIe (or, heaven forbid, a Mark Ve) is being used on these units. And, if there is a watchdog timer problem, then the Speedtronic can trip the turbine by shutting off the fuel, which will then cause a reverse power condition which can sometimes actuate the generator lockout relay or actuate some other generator protective relay which then actuates the generator lockout relay before the shutdown signal is sent to the EX2000.

I've seen battery grounds and power supply problems cause these kinds of problems. Also, it's all too common for trip signals to the TREG card to not be properly identified and alarmed, and that can be very, Very, VERY misleading.

So, it's not possible to have enough information to say definitively what caused the problem, but hopefully you have some possible causes to look at. Carefully review the printout of alarms from the trips. Properly identify what was the first trip condition that was annunciated, and realize that the Speedtronic, rightly or wrongly, can also think that subsequent conditions (which would have resulted in a trip of they'd occurred first) can be annunciated, even though they were not the original cause of the trip.

And, make sure that any trip inputs to the TREG are properly identified with signal names and process alarms to alert the operator when they are "actuated".

In the future, please provide as much information about the site's control system(s) as possible for help. But, do realize that without being able to see the Alarm Logger printout(s), it's virtually impossible to be able to say with any degree of certainty what tripped the unit.