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Transformer Testing & Maintenance


Optimal Transformer Efficiency Using Weighted Average

In order to improve the efficiency of electrical distribution in commercial buildings, the US Department of Energy (DOE) introduced regulations with more stringent minimums on transformer efficiencies in January 2016. This was covered under the Code of Federal Regulations 10 CFR Part 431.192 and...

Power Transformer Failures

Electric utilities maximize utilization of their assets, while maintaining reliability. Power transformers are typically reliable, but have been known to fail suddenly and/or prematurely. Transformer failures are both costly and can leave customers dissatisfied, harming the reputation of a utility....

Transformer Testing & Maintenance

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Dielectric Voltage Testing – Standard Methods

There are two standard methods from ASTM International: D877, Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes, and D1816, Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Using VDE Electrodes.

VDE stands for Verband Deutscher Electrotechniker—the Association for Electrical, Electronic, and Information Technologies— a German standards organization similar in function to the Institute of Electrical and Electronics Engineers (IEEE) in the United States. The D1816...

Related Articles


Insulation Resistance Test

Insulation Resistance (IR) test, often called Megger test, is more than 100 years old and assumed to be a very straightforward test. During my inspection and testing work in the past 15 years in Canada, US, and internationally, I have seen different practices of performing and interpretation of IR...

Harmonic Problems in Power Transformers

Preventing malfunction in power transformers BY ANDY SAGL, Megger Harmonics are another power quality phenomenon that can cause equipment to malfunction. Harmonics are a sinusoidal component of periodic waves that have frequencies that are multiples of the fundamental frequency. Harmonics can cause...

The Dissolved Gas Analysis Toolkit

Dissolved gas analysis: addressing the challenges of collecting samples BY DONAL SKELLY, GE’s Digital Energy business Dissolved gas analysis (DGA) is a technique for identifying and quantifying the gas formed in oil-filled electrical equipment because of either the natural aging of oil and paper...


Cyber Threats on the Rise Invest Now to Boost Power Grid Defenses

Critical infrastructure security is in the national spotlight. In 2020, the power grid and energy sector was the third most targeted sector for cyber-attacks, up from ninth place in 2019, and the threats are growing more sophisticated. The Biden administration recently issued a national security...

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Dielectric Voltage Testing – Standard Methods

There are two standard methods from ASTM International: D877, Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes, and D1816, Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Using VDE Electrodes. VDE stands...

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Case Study: Rapid Changes in Bushing Health

IntroductionContinuous online monitoring of bushings provides real-time information which can result in the early detection of a possible failure. Challenge: A Major AlarmA prominent U.S. utility was looking for a way to improve system reliability for their 138kV assets. They researched and...

The Distribution Transformer - Critical Power System Component

By R.W. Hurst, Editor A distribution transformer is a critical component of the electrical power system, used to reduce the voltage of electrical energy for electric power distribution to end-users. It plays a vital role in voltage regulation and load management, ensuring the efficient and reliable...

Grounding Transformers Explained

By R. W. Hurst, Editor Grounding transformers are used to provide a path to ground for unbalanced load current and for fault currents on systems where a suitable ground is otherwise not available. Grounding transformers are normally constructed with one of the two configurations: Zig-Zag (Zn) with...

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