Detecting Spark Discharge in 7FA Lube Oil Filter


I am trying to find the root causes of varnish formation in our 7FA lube oil tank. One of the root causes I came across is the spark generated when oil passes through the lube oil filters. also there is another reason which is air bubbles in the oil but this is not our topic.

I want to check if our 7FA has a spark discharge.So,if anyone knows a good method to check the spark, please share it here.

Thank you.

I don't know if there's a way to visually test for this phenomenon--I've never seen one performed, and have only read about the phenomenon in trade journals and literature.

Varnishing is not usually the result of a single condition; it's usually a combination of things.

Was the oil regularly sent out for testing (quarterly; bi-annually; annually)? If so, what were the results?

How long was the oil in use?

When was the oil installed in the unit?

What are the operating conditions (daily start/stop; peaking application; Base Load application; load-following application)? Are there long periods of non-operation, or turning gear operation, between loaded operation?

Has the L.O. Mist Eliminator been continuously in service with no problems, and was the L.O. Mist Eliminator regularly serviced, and elements replaced as recommended by the manufacturer?

There are a LOT of conditions which can cause varnishing. And, spark discharge in the filter is just one of many. It is agreed it would be helpful to know if it's occurring and if so if it could be mitigated with some change in filter elements or other protective measures.

Many times the L.O. vendor/refiner is willing to help with these kinds of inquiries, as well as the filter manufacturer--both want to know about improving conditions and equipment and reliability and longevity.

It would be very much appreciated if you could write back to let us know what you've learned. A lot of people follow these GT-related posts on learn a lot from them. Thanks!
well, thank you for your reply.

As you said, combination of conditions causes the varnish.
the oil is tested monthly (NAS value not reached 7). The oil we have since 2008 and it has never been replaced. usually the load in early morning is 90 MW, and near the noon it will be 140MW.

for the mist eliminator, usually it is running okay, but of-course there were times of malfunctioning.

this forum is really helpful. I hope we can learn from each others about best-practice and successful modification of 7FA.