Product News! Product News! Product News! Product News! Product News! Product News!
Before you read my blog….
Have you ever been to the doctor for a routine checkup and been given bad news? If you’re at all like me the first thoughts that form in your mind will be “I’m going to get a second opinion!”
Darn Right you are!
Because there’s a lot riding on it! And as we all know, doctors are only human, they are not infallible. Well the same holds true for your electrical equipment. When your equipment gets an annual physical checkup from your testing company do the results sometimes come in less than good? Along with those results do you get a list of options proposing “Major $urgery” on it? Maybe it’s time to reach out for a second opinion. Luckily you may not have to reach too far. If you have my dissolved gas analysis program in your toolbox you can verify those results immediately…or not! Think about the upbeat calls you’ll get from your clients when you tell them that you’re going to “anesthetize” their transformer for a half day or so to perform major repairs . OR……Think about how cheery they’ll be if the analysis said it was okay and the unit blows up two weeks later. Believe me it can and does happen. All of the good engineers I know have an inborn instinct to minimize risk, and I’m sure that you are one. One of the golden rules in preventive maintenance is maximizing safety and reliability along with minimizing costs.
Try this program today. The software is:
· Simple to Operate
· Easy to Understand
· Confirms (or not!) Your test lab’s recommendations
· Works on any windows compatible computer
From the comments that I’ve seen so far, this program is invaluable. Just click on the button below for your copy and your CD will be on the way! All shipping within the states is free!
Thank You!
Transformer Oil Reclamation Continued
Hot Topic
In this post we need to talk a bit about heat. Heat is an extremely critical element in transformer oil reclamation. The filtering media will strip the sludges and acids from the oil but unless the oil gets hot enough the sludge that is deposited on the interior surfaces of the equipment will stay there. If it is not removed it will harden and begin to crack along with the insulation that it has formed onto. Essentially hot oil melts the sludge deposits in the transformer. The transformer oil aniline point is right around 160 degrees Fahrenheit. Aniline point meaning the point at which is begins to act as a solvent. Transformers are cleaned much the same as if you run clean water into a muddy bucket. The more water that you flush it with the cleaner it gets. Cold oil will dissolve sludges over time. Evidence of this is available from test results taken after an oil change in a dirty transformer. Over a period of time the new oil will pick up some of the sludge in solution and it will show up in the tests by a rapidly dropping IFT reading. I use the term rapidly relatively. It should take about two years for the IFT in a lightly loaded unit (25C) to stabilize. At that point the oil is usually saturated and you start deteriorating where you left off at the oil change. You can change the oil again but this is an expensive and wasteful way to clean one out.
Heating filtering and re-circulating really works best in this case. Keep re-circulsating until the test results stabilize on the oil and you will have rid the unit of most of the sludge contamination. The temperature of the oil coming out of the reclamation unit needs to be between 180 and 200 degrees. That because it’s going into colder oil and the entire apparatus needs to reach at least the 160 degree mark. Remember that the cooling fins are normally functioning while the transformer is being treated and they will cool the oil somewhat. Ideally your oil processer should block off the fins to delete any “cold” spots that would allow sludge to accumulate or not be dissolved.
Heat also makes the filtering elements more active. In the case of fullers earth it becomes much more active and efficient at removing acids at elevated temperatures. The same goes for the vacuum system that is removing the moisture from the system. Oil will hold more moisture in solution at elevated temperatures and therefore is likely to change the equilibrium reached inside the unit between the oil and the cellulosic insulation. That can cause the insulation to unlock and give up some of it’s moisture to the oil. That oil then goes back to the processing equipment to be vacuumed.
There are still a few engineers out there who are not proponents of energized processing. Since this has been done successfully on a regular basis since the 1960’s I don’t agree with them. Energized processing gives you the extra boost of the internal heat generated by the transformer, and that helps drive moisture out of the insulation into the oil to be removed in the processer. As soon as you shut the unit down the moisture in solution will start to migrate over to the insulation degrading the integrity of it. It may not be much but with today’s design criteria it doesn’t take much.
As for those who think it’s bad business to circulate oil in a running transformer, I suggest that you look inside the next time your sampling technician takes the top off of a small energized unit with cooling fins (especially a hot one). You can actually see the oil moving through the unit. As the oil is heated by the core and coils it rises to the top and then as it passes into the cooling fins becoming more dense as it cools it drops to the bottom only to repeat the process. If it weren’t ok to move the oil around in a transformer the big ones wouldn’t have circulation pumps in the cooling fins. The trick is to keep the level constant with a relatively gentle flow. As long as you don’t get gas bubbles you will be ok. I should also note here that the oil is drawn into the processor from the bottom of the transformer and reintroduced through the top. Drawing from the bottom alleviates the problem of stirring up sediment. In most cases it goes into the processer to be removed and never gets stirred up around the current carrying parts of the equipment. Energized hot oil processing is safe and effective when performed on qualified equipment by experienced technicians.
That’s about all I have for today.
Any comments or suggestions are always welcome. If you have a question my email address is: transformerbob@gmail.com
Today’s quote comes from the boss-
“Employees are like mules, Some you stand in front of and coax along with a carrot. Some you stand behind And kick them in the ass. The key to management is knowing which mules are which!”
Don’t forget to order a copy of my transformer oil gas analysis program. It’s a great tool to have. You won’t regret it. When you need it, it will be there.
Thanks,
Bob
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