Technical library

Technical library

The Megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Use the filters to browse specific content (e.g. application notes) or refine your search to a particular electrical application area. 


If you would like to see the content we have available on a particular subject or need to locate some software, simply enter a search below. Please note, you will need to create an account to access some resources.

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DFR: A New IEEE Guide for Field Test on Power and Distribution Transformers
Since the invention of the transformer, the design, quality and efficiency of this magnificent machine has been improved thanks to the development of electromagnetic materials, computer design algorithms, insulation materials, cooling systems, structural design, etc. Nowadays, a vast number of transformers operate worldwide aiming to provide reliable and safe operation under the most cumbersome environmental and operational conditions.
Published: 15 April 2019
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Diagnostic Test: 1-500 Hz Narrow Band Dielectric Frequency Response
For approximately 25 years, dielectric frequency response (DFR) has been investigated and proven to provide an accurate method of determining both the moisture condition of paper + oil power transformers and bushings. Together with general insulation testing, DFR provides enhanced insulation condition of the transformer under test.DFR testing method is now accepted internationally – as evidenced by its inclusion in the CIGRE TB445 as an accepted method for moisture determination. IEEE is presently in the process of completing a new guide for use of DFR in transformer moisture assessment for both factory and field testing, which should be completed and available by 2019. Instruments like the Megger IDAX300, which was the first commercially available unit to perform this test, is a valuable tool in this determination of moisture content.IDAX300 has included the ability to perform PF tests at frequencies from 1 to 500Hz which can be defined as a narrow frequency band dielectric frequency response test. We are now able to provide a shorter duration DFR test which gives us additional information into the overall insulation condition of the transformer or bushing.This paper illustrated a narrow band DFR test performed on a transformer located in Thailand – EGAT (power utility) and the result was recorded. It is proved that narrow band DFR test can provide a base line for any future testing comparison. We can use both a curve shape and/or a trend change for looking for issues. We no longer need to only rely on the line frequency PF(DF) to detect future issues.
Published: 8 January 2019
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Pre-locating faults with alternative method to arc reflection
While the share of installed cables without a jacket generally continues to decrease, the unjacketed cables that remain continue to age. As they do so, it is increasingly likely that a fault will develop on these cables. It can be particularly troublesome to locate faults on unjacketed cables as normal Time Domain Reflectometry, or radar, based fault location techniques often do not work, due to the corrosion of the neutral wires. While there is no guaranteed action that would result in locating the fault, this paper will outline some advanced methods, based on field experience, that can help when locating these types of faults. This paper was an article presented at NETA in 2017 and will discuss the Impulse Current method, which does not rely on the neutral wires being intact, in both a theoretical and practical light. 
Published: 14 February 2018
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Power transformer demagnetisation
Abstract-Switching operations and direct current applied during routine testing procedures of static winding resistance measurement leave residual magnetization in the core and/or fully saturate the core of the transformer.
Published: 22 November 2017
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Oil-paper insulation voltage dependency during frequency response analysis
Dielectric Frequency Response, DFR is the extension of power factor testing except that the measurement is performed from 1 kHz down to typically 1 mHz. It is a very useful tool for evaluating the moisture content in solid insulation of HV and EHV components such as power transformers, bushings, instrument transformers and PILC cables.
Published: 20 September 2017
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Effects of Low Resistance Measurement Instruments on Protection and Control Devices
This paper will provide an insight into the factors that can go wrong during micro ohm measurements and how to prevent those using a proactive approach.
Published: 9 August 2017
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Offline PD diagnostics using several excitation voltages
Diagnostics on both MV and HV cables is used as part of commissioning tests to check the quality of workmanship of newly installed cables and accessories. This paper goes into detail to all available excitation voltages for offline PD diagnostics.
Published: 1 June 2017
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Best practices for offline diagnosis of medium voltage cables
The continuously increasing installation complexity for medium voltage power cables, results in many weak spots and therewith cable failures due to bad workmanship. This is mainly caused by the large variety of cable accessories as well as the reduction in insulation thickness and therewith in the margin of error throughout the entire cable installation process. The necessity for both commissioning testing of new cables as well as diagnostic measurements as part of a condition based maintenance is just a logical given fact. Nowadays cable testing as well as condition monitoring are well proven measurement methods for MV power cables which are guided by IEEE 400 [1] and IEC 60502-2 [2] standards.
Published: 1 June 2017
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UHF PD-Diagnosis at high voltage cable terminations – International case studies
Different partial discharge defects show a different distribution in the frequency spectrum. These typical characteristics could be used in combination with the appropriate phase resolved partial discharge pattern for the analysis of partial discharge defects. The classification of the partial discharges allows an assessment of the defects in terms of its criticality.
Published: 1 June 2017
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Individual temperature correction (ITC) for insulation resistance measurements
The value of insulation resistance (IR) is strongly affected by the temperature of the material. However, in most cases IR measurements are done at the operating temperature of the given device. For this reason temperature correction is required to ensure that meaningful conclusions can be drawn from the measured values of IR
Published: 31 May 2017
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  • Showing item(s) 1 - 10 of 25 in total