Turbine Trip On Low Control Oil Pressure

Could you translate your question in to an acronym free language please.

Yes, it could. It could also be a red herring. What is clear to me is that you have an ESO incident. Please seek appropriate action.

Might be. Might not be. I wasn't there so how would I know?

That might be the reason because the turbine is now confused since all the controlling devices are operating at the same time. Reset the controls according to their operation parameters and check the oil pressure.

Check the oil.

Find the dipstick that did not check the oil reservoir during run time, before run time, and after run time. Fire him instead.

Other than that, use your own noodle, and the plans for your machine, and the best advise of all RTFM daily, until you know your machine inside and out.

Yes and no...

http://www.nrc.gov/docs/ML1122/ML11223A295.pdf

Dear Mr.naved112,

In my opinion, the low oil pressure mainly caused due to low level in the oil reservoir, very high temp. of oil, and excessive clearance of oil pump, defective oil pressure regulator, oil partly by-passing etc., etc.

Pl. check for the above.

Pl. post - how the problem was solved.

DHAYANANDHAN.S

thanks for your valuable feedback. in the main header, there are two branches, one is going to lubricate the bearing after PRV and other branch going to control oil system with an orifice. the main header pressure was stable, but control oil pressure drop down to trip level, the reservoir oil level was ok, the same pump gives the required pressure after restart. last oil was replaced in 2013 during TA. what else could be the reason.

You say the oil hasn't been changed in three years. This site states a common oil change for turbine oil of 5 to 7 years due to the large reservoir size. Depending on the the environment and many other factors the oil batch from three years ago may have prematurely degraded. The above site does show that ASTM D4378 guideline standard states when turbine oil should be changed. Who knows, three years ago you may have acquired counterfeit or used oil for this turbine.

IN the time since oil change: have you (1) ever centrifuged the oil to remove condensate coming in at the oil seals against steam?, (2) have you done screenings to check for metal particles, or a magnet test?, (3) analyzed the oil for wear metals on a routine basis?, or (4) checked the control oil system orifice for blockage?

I think you need to do some more work, some investigating, and a check up from the neck up if not doing all to keep the oil clean.

Now that you have given some more details it requires a different answer.

I read the link from Solar Eagle,and it was very explanatory of your possible problem areas,and almost points an arrow to it.

The control logic and strategy is laid out in simple easily understood form.

I will not cheat you out of the learning experience,so read and comprehend the info

in the link,and you will have gained more knowledge of the system that you currently

possess,and you may prevent many future problems.

You will be considered the GO TO GUY for the system eventually

You will learn that diligent pursuit of a solution to a well defined problem will yield

better results than soliciting a quick fix for your problems from a forum.

You are certainly welcome to post question here,but a problem well defined is half solved.

What causes the low pressure trip? Could it be a faulty sensor or switch? Is there a voting type of logic in the trip scheme? Is there a first in/first out logic scheme in the control system?

Check for an operator "I dee ten tee" error.

The reason for the trip is the low oil pressure.

I know very little about your particular system,but based on experiences with other

systems with similar problems,it sounds like a system oscillation that becomes

amplified by loop responses that have the gain set too high.

This can create a feedback loop that will create an eventual shutdown.

Introduce a delay in the system that is sufficient to override small disturbances in the system.

On the other hand,the "problems" you see may be a normal response to a sudden shutdown,triggered by the low oil alarm.

You may be over analyzing the problem.

To fix it: Maintain proper oil level and pressure.

This sounds like a very old system that you are trying to keep together with Duct Tape and WD-40. Apparently you have a single oil supply system that provides both control oil and lube oil pressure, without any obvious redundancy found in any modern turbine control system. Systems such as yours have multiple single points of failure since a loss of control pressure appears to produce the modern equivalent of a METT (Master Emergency Turbine Trip); therefore anything that affects the oil pressure will take the unit off-line.

You need to ensure that everything that is involved in that system is operating properly; that includes the pump, oil level, all sensors, check valves, pressure relief valves, control/diverter valves, etc., etc.; basically anything that the oil touches needs to be verified as calibrated and operating properly.

When you're through with all that, then you can start checking your seal and lube oil supply systems. A two-three week 7x24 maintenance outage should do it, assuming that you hire some competent companies to perform the work.