low level oil tank of turbine do not trip the machine

we have a GE turbine 5002C training 3 BCL compressors where seal circuit was with oil, after some issue the oil went with gas circuit inteal the low level alarm was shown on HMI but the turbine do not stopped, in this case we think that is dangerous if we lose all the oil in the leakage because the turbine will be without lube oil. also in the logic control there is no trip signal from this alarm.
please provide us any idea about it.

As the oil level drops in the tank the main and auxiliary lube oil pump discharge pressure will fall, and the unit will (eventually) trip on low-low lube oil pressure.

The emergency lube oil pump suction is usually at a lower level in the tank so it will provide oil flow to the bearings as the unit coasts down to zero speed.

Doesn’t it all really depend on the rate at which the lube oil tank level is falling? In other words, doesn’t the severity of the situation causing the oil level in the tank to fall affect the ability of the design of the system to protect the bearings as much as possible?

How likely is it that the severity of the loss of lube oil will lead to an inability to maintain oil flow to the machine bearings until the machine can reach zero speed? And if the machine rotor is hot when the speed gets to zero before the oil flow is completely lost the heat of the rotor will damage the bearings without oil flow to the bearings for cooling.

But, the above is posited without being able to review the P&IDs for the machine and without understanding the possible severity of the loss of lube oil (the flow rate of the leak).

How do you propose to mitigate the possible problem we can’t understand without more details? Use redundant level lube oil tank level transmitters and initiate a trip on some combination of level and rate of decrease of level?

Again, this is posited without really being able to understand the configuration of the system(s) and the potential for high leakage flow rate. Not everyone (me included) knows what BCL compressors are how they are sealed and lubricated.

But, I hope this helps to at least point out how important it is to always refer to the P&IDs when researching a potential problem like this. And, if there is a real concern about the possibility of a severe leak then you should be involving the packager of the turbine and compressors to get their input on how to mitigate the potential for machine damage. Insurance companies don’t want to pay for damage when it could have been avoided or should have been foreseen.

Best of luck.

Also, the human machine operators have to be capable of responding to situations like this. Relying on automation to react to every possible problem means human operators are not necessary…. Hopefully machine damage was avoided in this case because alert human operators were aware of the situation and shut the machine down before serious damage occurred.

It’s possible to have instrumentation and automation try to protect the machine in the majority of possible situations, but well-trained and experienced human operators are still the last—and best—line of defense.


Autonomously-operated plants are a long way off (I sincerely hope, anyway). And I don’t really want to think about a world without human operators—well-trained, experienced human operators. Because machine learning and AI (Artificial Intelligence) ain’t ready for prime time on high-speed rotating equipment burning combustible fuel and moving combustible product (just yet, and hopefully not before I pass on from this world in my personal opinion).

What will a world look like without human operators? How will plants and protection be designed and implemented without experience?
thank you dear CSA for this beautiful clarification.
be informed that our issue is solved where the leakage was not big (a level transmitter on the rundown tank).
but for me I did not now the real position of pumps in the tank so I was not sure about the reaction in case of low level.
thank you again and good luck