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GE Mark VIe Lock-out
Getting a better understanding of GE Mark VIe turbine lock-out (L5RtrLck)

I am another newbie to the GE Mark VIe family.

I was recently asked by a friend to assist with a root cause analysis on some issues with a GE turbine (I have never dealt with any of these before. No experience with GE systems).

The problem at hand surrounds a 4-hour lock out (L5RtrLck) - (during this period, the turbine cannot be started until a lock-out period expires).

I set out trying to see what I could find from the application code(.pdf) document I got from him. Most of the knowledge used was from my experience with PLC ladder logic. I am certainly no expert at GE. I have made some notes on my analysis of the logic (also in .pdf) but was wondering if you could possibly review these for me please.

There seems to be no medium for uploading files on this forum (or is there?), so perhaps one would have to go through emails.

If it is not too much trouble for you, I would like to send my findings to you. I can be reached at

Thanks for your time.

What model is the turbine? If it is an Aero-Derivative (LM series) it can have a lockout before restart.

I'm not a 100% certain, but I believe it's an LM1600 SAC.

2 out of 2 members thought this post was helpful...

Dear BlueGene, the somewhat generic answer to your question is that most LM=Land Marine aero derivative gas turbines require a scheduled shutdown sequence.

Part of this shutdown sequence is typically a crank period that allows turbine rotating and non-rotating components to cool down at a somewhat equal rate. This is done to prevent contact of rotating blades and buckets with the outer case when the case cools rapidly and shrinks at a faster rate than the blades and buckets.

If the normal crank cool portion of the shutdown is interrupted or not executed then the unit is put into a "lock-out" where it is not allowed to be cranked or started due to the potential for tip rub and mechanical damage.

Most of the logic for these machines is pretty "mature" and has been pretty well vetted. Removing lock-outs would not usually be advised. But understanding the reasons for the lock-out and ways to avoid them is definitely something I would recommend.