Investigating multifunctional in transformer diagnostics

Megger traxMegger’s TRAX transformer and substation test system instrument provides thirteen different testing capabilities for transformer diagnostics alone, as well as extensive test capacities for other system assets, such as capabilities to time and record motion on circuit breakers

The value proposition of off-line electrical testing, such as for transformer diagnostics, is strengthened as the costs associated with testing are reduced and the diagnostic reach of the information grows.

Multifunctional instruments, whereby the testing capability of multiple instruments is included in one, are increasing in popularity because of costs savings; through easier usability, manageability and transportability, lower equivalent upfront costs, and the on-going savings of an associated switchbox that reduces test time for transformer diagnostics. Technical features of a multifunctional instrument also determine the magnitude of savings provided as well as the degree to which the value of the results is enhanced. A potential misstep of a multifunctional instrument is losing “balance” – sacrificing transportability, unrealistically compromising testing capability, or becoming difficult and confusing to use as more functionality combines. 

Balance, in particular, is very important. Desirable outputs/sources must be provided while avoiding excessive instrument weight and size. While the power sources should not be overbuilt, they must be adequate for the test at hand. Easy usability must be preserved while providing ample versatility.

Megger’s TRAX, the main section of which weighs just 26kg, excels in attaining this balance. The outputs are pragmatic. The user interface of the TRAX, which utilises the latest colour touch-screen technology, presents functions in the form of apps.  When the user has decided what to measure and has selected the app/instrument to work with from the start screen, the display shows only those elements that are appropriate to that function. Guidance is provided in the form of connection diagrams and tables that provide the correct sequences of tests. The TRAX delivers a simple testing experience for the user, who will feel well supported across all of its functions.

A multifunctional instrument’s switchbox provides time savings and reduces fall hazards by minimising the overall number of ladder climbs to complete testing. Switchbox cables are connected initially to each bushing terminal. The switchbox is a “router” between the test instrument and the test specimen that “determines which track the train is directed” so that connections to bushing terminals do not have to be moved after completion of each single phase test. It is desirable to maximise the number of tests a switchbox can facilitate (Megger’s TRAX switchbox facilitates seven different transformer diagnostics) and, here too, maintain balance. Switchbox cables to each bushing terminal must be manageable, safe and affordable while the ratings of these leads remain practical for the intended tasks at hand (particularly for winding resistance measurements) lest negating the ability to successfully complete a test and benefit from the conveniences of automated switching between tests.

Not only is Megger’s TRAX an extraordinarily balanced multifunctional instrument, it is packed with technically differentiating features that boost asset condition awareness. True dynamic resistance measurements of load tap-changers, TRAX’s adaptive demagnetisation procedure, and elevated insulation diagnostic capabilities through dielectric frequency response (DFR) measurements together with patented techniques for temperature correction (ITC), and voltage dependence detection (VDD) so that you only perform power factor tip-up tests when necessary. According to Megger, TRAX is arguably the best transformer test instrument available today.

Alain Charles Publishing, University House, 11-13 Lower Grosvenor Place, London, SW1W 0EX, UK
T: +44 20 7834 7676, F: +44 20 7973 0076, W:

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