Attending and presenting at the ISH 2021

Attending and presenting at the ISH 2021

ISH 2021

ISH is one of the most influential international conferences with large scale and high academic level in the field of high voltage and insulation technology. Experienced scientists, researchers, and engineers in the field of high voltage engineering from different countries participate in the oral sessions at ISH. The academic committee of ISH 2021 already invited top experts in the field of high voltage engineering to give plenary and invited presentations throughout the conference on current topics of Interest. ​For more information please contact us at 

Megger appreciates the invitation of the ISH academic committee to participate with an invited presentation by Dr. Diego Robalino, Megger's Business Development Director – Power Transformers. He will speak during Session 17 from 08:30 to 08:55 on November 25. The topic of his presentation is “Novel Approach for Insulation Condition Assessment of High Voltage Substation Equipment at 1 Hz”.

The technical article is authored by Megger's Dr. Diego Robalino, Mr. Vince Oppedisano (Transformer Product Specialist), and Mr. Kenneth Petroff (Transformer Product Manager).

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About the Author:

Diego Robalino is the Business Development Director – Power Transformers at Megger.  Diego is a Senior Member of IEEE, a member of IEEE/PES Transformers Committee, a certified Project Management Professional with the Project Management Institute (PMI), and the General Chairman for the IEEE/DEIS 2022 40th Electrical Insulation Conference. He is the author and co-author of over 40 technical articles related to power, distribution, and instrument transformer condition assessment. Diego received his Ph.D. in Electrical Engineering from Tennessee Technological University. 

Paper Abstract:

In the field, it is common practice to evaluate the average condition of high voltage substation equipment by measurement of dielectric losses. This practice involves applying an AC signal to an insulation system (capacitor) at a frequency close to the line-frequency (60 or 50 Hz) and measure the current and the angle between current and applied voltage to determine the insulation dissipation factor or power factor (also known by the term of tan delta).

Line-frequency insulation dissipation factor (DF) or power factor (PF) depends on the frequency of the applied signal, dielectric properties of the insulation material, insulation temperature, geometrical design, as well as aging and contamination that might be present within the insulating medium.

The field experience suggests that the use of table correction factors for temperature correction does not reflect the true thermal behaviour of the insulation system and any trending analysis turns out sometimes misleading due to incorrect temperature correction. Throughout the service life of an electrical asset, line-frequency DF may not change, may increase or sometimes it may even decrease, but the reason for these changes is not always clear.

The research work carried out by the authors shows that even a “good” line-frequency DF is not always “good” and that assessment of insulation should consider one more DF value obtained at a different frequency to properly and reliably determine the condition of the insulation system.

This document provides a clear understanding of the benefit of testing for insulation DF at line-frequency (50 or 60 Hz) and 1 Hz. A simple procedure carried out at the same time and with the same test set provides a more reliable and more efficient way to evaluate the condition of critical high voltage substation equipment including power transformers, bushings, and instrument transformers.

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