9E Generator Trips on Open Breaker When Under Excitation


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dear friends

I appreciate if someone want share his experience regarding the problem with gas turbine 9 E trip excitation brushless system with 145 mva apparent.

The generator under excitation, the breaker 52G opened in p = 60mw with q = -82mvars, but in cababilite cuve when p = 60 mw the q =- 66mvar.

please cause of opened breaker 52G
1. opened breaker 52G
2. NOo alarms
3. But under excitation out for cababilite cuve -82 mvar
4* breaker of excitation 41 no opened. why?

system brushless avr100s d


<b>Moderator’s note:</b> There were many misspelled words in this post. I corrected some but could not figure out others. I think cababilite cuve is capability curve but not sure

When a GE-design heavy duty gas turbine equipped with a Speedtronic ("Mark") turbine control system trips <b>A PROCESS ALARM IS ALWAYS ANNUNCIATED TO INDICATE WHAT CAUSED THE TURBINE TO TRIP.</b>

So, to answer your question, you need to look at the Process Alarm printout from the Alarm Log printer to determine what tripped the turbine.

Sometimes the turbine is tripped through what's called a lock-out relay--a device with an ANSI device number of 86. Lock-out relays can be actuated by any one of a number of devices in the generator protection scheme, so it may be necessary to look at the generator protection relay(s) to determine what relay/function is actuating the lock-out which is tripping the turbine.

A lock-out relay usually requires a human to manually reset it (by twisting the handle to re-latch the relay). If a lock-out relay must be re-latched in order to re-start the turbine then some relay/function is actuating the lock-out relay and you must determine which one and what condition is being detected to cause the relay/function to actuate the lock-out relay.

Because the post is unclear it may be that you are describing what's commonly called a "load rejection" event--where something opens the generator breaker but doesn't <b>also</b> trip the turbine. If this happens and <b><i>then</b></i> the turbine trips (the alarm which would be annunciated would be "LOSS OF FLAME TRIP") then the problem is that the minimum fuel flow-rate (Minimum FSR) calculation is not correct and you will need to get someone to site to help with the problem.

If the turbine trip is occurring when the grid frequency is unstable--particularly if the grid frequency is VERY unstable--then there's probably not much which can be done to prevent a turbine trip from occurring.

But, with all the above being said, again <b>EVERY TIME A TURBINE TRIPS A PROCESS ALARM IS ANNUNCIATED (AND LOGGED TO THE ALARM PRINTER) TO ALERT A CONSCIOUS OPERATOR AND OPERATIONS SUPERVISOR WHAT CAUSED THE TURBINE TO TRIP.</b> This is always true, even if the trip message isn't clear or intuitive. Even the cryptic "LOSS OF FLAME TRIP" is true: something caused the fuel flow-rate to be less than required to maintain flame and this will result in a turbine trip (one doesn't want fuel to keep flowing into a turbine when flame is not present--because of something DOES ignite all that fuel, then there is going to be a very large, destructive and potentially deadly <b>BOOM!</b>).

Lastly, there is a very distinct difference between a "trip" and a "shutdown" for GE-design heavy duty gas turbines. Many times people call a shutdown (an orderly reduction of fuel until flame is lost (usually around 20-50% speed) and then then unit coasts down to cooldown (turning gear; ratchet) and a trip--which is a very fast stop of fuel resulting in a coastdown from rated speed to cooldown. A trip is also known as an emergency shutdown--it's to protect the turbine and/or generator from a potentially damaging condition. A shutdown is just like when an operator clicks on STOP; the fuel is gradually reduced until the unit flames out (around 20-50% speed) and then it continues to coast down to cooldown. If the grid frequency is very unstable when this problem is occurring and the generator breaker opens when the turbine speed is less than approximately 95% speed the Speedtronic will automatically go into a shutdown (controlled reduction of fuel to flame-out and cooldown) and some people mistakenly call this a "trip." So, it's not really clear if your problem is an emergency shutdown or a normal shutdown, and the conditions of the situation leading up to the "trip" are also not clear.