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Understanding Your Test Results

One of the most important functions of oil in a transformer is to protect the paper (solid insulation).  As oil ages, it loses its ability to protect the paper from degradation.  Aging also weakens the oil’s ability to act as a cooling medium and provide dielectric strength – ultimately protecting the transformer from failure.  Through the aging process, chemical by-products build up in the oil and the paper, creating acid by-products and sludge. These decay products begin to affect the oil’s protective qualities almost immediately after they form, they begin to break down the molecular structure of the solid insulation.

7 Challenges to Overcome in Developing Electrical System Reliability

There are very few organizations that are not concerned with following reliability best practices. It is more efficient and less expensive to prevent a breakdown than it is to fix something that breaks. Monitoring and data management are becoming ubiquitous in the industrial world, the utility world, and across most industries and sectors as we work towards a more reliable and interconnected future. Electric power systems have not been included in this shift away from break/fix and towards data-centric reliability, and what the future holds for organizations seeking best practices.

Load Tap Changers: Testing Insulating Liquids

Testing the oil in load tap changers (LTC's) provides valuable information on the operation of the unit. Monitoring conditions between preventive maintenance inspections is a critical step in preventing expensive maintenance problems and even unplanned outages. This first article in a series will address the aging of mineral insulating oil in an LTC.

Ethane Levels in Natural Esters

Over the years, customers have asked us a variety of questions about dissolved gas analysis (DGA) results that indicate elevated ethane levels in natural ester fluid. Natural ester-filled transformers, specifically those filled with FR3, have a tendency to generate ethane—and sometimes hydrogen—as stray gasses at temperatures normally found in a properly operated transformer. While not typical in every case, it does happen frequently enough that we do not consider it to be abnormal. 

Transformer Oil DGA Monitoring Technology

As use of dissolved gas analysis (DGA) monitors increases as a growing component of transformer maintenance and reliability, it is imperative to understand the capabilities of monitors in their ability to align with conventional laboratory results and detect gas-related changes from a baseline. SDMyers studied DGA monitors from several manufacturers through experiments over 18 months. Technologies included in the study were gas chromatography, photo-acoustic spectroscopy, solid-state palladium, thermal conductivity detection, and selective membrane methods. This paper summarizes conclusions from that study based on technology employed.

Will Changing Oil Solve an Acid Problem?

You cannot just change the oil to lower the acid number to an acceptable level in place of a hot oil cleaning. Changing the oil will not permanently reduce the oxidation byproducts in the solid insulation. It is not an appropriate maintenance solution for lowering a high acid number.

Sampling - Part 3

Regarding containers for Karl Fischer Moisture Analysis, SDMyers has found that a glass bottle functions as an excellent container for moisture analysis, if all of the following conditions are met: Before sampling, the capped bottle is kept dry by using a desiccant tablet; the glass bottle has a metal cap with a Teflon liner; when sampling, the bottle is filled to the very top in order to minimize the gas space in the bottle; and the KF Moisture test is the first test performed out of the bottle. Using proper sample containers will help ensure that your samples are representative of the actual conditions inside your electrical equipment, enabling proper diagnosis to extend the life of your transformer.

Sampling - Part 2

Information about your electrical equipment is critical but is of limited use by itself. Laboratory testing is also required to get the most accurate diagnosis, but accurate and representative test results are dependent on getting a good representative sample.

Sampling - Part 1

Oil testing can diagnose unseen problems inside a transformer. Mineral oil comes in contact with the internal workings of the transformer and contains valuable information regarding the condition of the transformer. Information about the equipment and a properly drawn sample are critical for making a correct diagnosis of the transformer's health.

PCB Testing - Part 2

In Part 2 of the PCB series, PCB regulations, and the classification of electrical equipment based on PCB test results is discussed.

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