Ensuring Transformer Reliability with Howard Penrose
It is my pleasure to welcome Howard Penrose back to the podcast.
In this episode we covered:
- Why are electrical reliability or electrical assets neglected?
- What are the major types of transformers?
- If we detect a high level of moisture in the oil, do we change the oil or is it a little more complicated than that?
Why are electrical reliability or electrical assets neglected?
Because they are scary and due to lack of understanding.
What are the major types of transformers?
You have dry type transformers, which are basically air cooled. You have encapsulated transformers in which the coils are encapsulated in an insulation material, and then you have oil type transformer. They’re all used in different types of applications.
If we detect a high level of moisture in the oil, do we change the oil or is it a little more complicated than that?
It’s a little more complicated because the minute you drain oil out of a transformer, the insulation will absorb moisture like crazy. You end up having to dry the insulation system, usually with nitrogen, then keeping a nitrogen charge on it while you’re adding well. Know the type of system that’s in there, whether it’s a bladder type or just a tank. Where does that oil go? Is it expanding and contracting? What type of oil do you use? There are systems there to filter that and remove the moisture from the oil.
What warning signs do organizations really have to look for with transformers?
IRR ultrasound, oil analysis quarterly a year at a minimum there and visual inspection. And then for the external part, including the bushings and connections, we’re talking about oil filled right now. Do an infrared for that. Do voltage and current analysis. Make sure that you’ve got some type of continuous monitoring or visual monitoring, get into vibration ultrasound, partial discharge, and other testing. Do acoustic testing and vibration or electrical signature.
What is the redundancy for transformers?
There is none.
What does a regular industrial facility do when faced by transformer challenges?
A lot of the smaller, dry type transformers, luckily, just like smaller electric machines, are common enough that you can get a replacement. But you still must go back to the original manufacturer because they’re not dropping. Part of it would be partnering up with a transformer company that has spares or set up, partnerships or look into the department of energy. The alternative is to set up.
Where does IOT fit into this?
There are some vibration technologies, some oil, continuous oil, Trent testing technologies, in the wind industry, there’s probably the more popular one is a company by the name of Poseidon. There’s partial discharge, continuous monitoring for your higher voltage systems, basically a lot of the stuff we use for electric machines, to transformers. When you’re testing equipment, start looking back towards the transformer. If you’re seeing impedance on balances and a loose connection reading, is there another thing you must look at? There’s a lot of our own technologies we use for other mechanical equipment that you can use on transformers.
Where do people go to learn best practices for setting up a maintenance program for transformers?
NFPA 70B is probably a good primer for that. CSA in Canada, I Tripoli in the states are probably the better ones for North America for that type of information. For just troubleshooting and looking at reliability, because we updated this one nicely, that would be iTripoli’s standard, C 57 1 25, um, which is called a guide for failure investigation of larger transformers. For oil analysis because you’ve got silicone, Ester fluids and other fluids that each now have their own standards.
The old standard for oil immerses transformers was withdrawn. There’s even like a C 57 12, which should be out by now. Drafts Dan well, the standard test procedure for thermal evaluation of insulation systems for dry type transformers. If you want to learn a little bit more about the design and troubleshooting, there’s a book called power distribution transformers, a practical design guide from CRC press. A little book by Nikola Tesla talks about electric machines.
What’s the one thing you want our listeners to take away from this conversation today?
Get a hold of the NFPA 70B, go into the transformer section and start applying the basics. Include your dry type transformers in your infrared route. Your internal distribution transformers should be right off the bat, and then begin looking at. Do oil analysis. Look if your supply is right. Start looking at what’s feeding it, because that can have an impact on the life of that system.
Howard Penrose Links:
- Howard Penrose LinkedIn
- MotorDoc LinkedIn
- MotorDoc Website
- NFPA 70B
- Book: Power and Distribution Transformers: Practical Design Guide 1st Edition by K.R.M. Nair
- Book: The Inventions, Researches and Writings of Nikola Tesla by Nikola Tesla (Author), Thomas Commerford. Martin (Editor)
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Lee Megois says
Transformer fluid testing has become somewhat harder with all the newer fluids available and some big fluid testing companies giving very “general” recommendations. I’ve seen reports state “arc or spark” when the transformer is only at 501 PPM Carbon Monoxide and has a ten-year history of non-detected PPM of Acetylene or Ethelyne. This is what Gulf Coast Transformer Consulting LLC does…. We work with the reliability folks at the site to help them understand their results, so they don’t waist their maintenance dollars on un-needed maintenance. We also review their current testing packages to make sure they’re not “over testing”…. Yes, that can be done easily, and the testing companies keep calling every year asking, “same thing as last year”. This needs to stop as well, and we can help.