Posts in Transformers
Reducing Transformer Risk: how ester transformer fluids are helping insurers

Transformers present a key challenge for risk managers and insurers. This whitepaper explores the effects of increased demands on the power transmission and distribution network. It looks at how the energy insurance industry can manage the risks presented by transformers through a strategic asset management plan, and how the use of ester-based dielectric fluid can help to minimise impact on the market.

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MIDEL Transformer Fluids Maintenance Guide

MIDEL 7131 and eN 1204 are robust fluids capable of giving long service, even in the most demanding of applications. As with mineral oil, in order to ensure that MIDEL fluids give continued good service it is possible to monitor a number of the fluid parameters throughout the life of the transformer. Testing the fluid also has the added benefit of picking up any potential problems with the transformer before a failure occurs.

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Transformer Optimisation: Extending asset performance and life

Transformers are one of the most critical assets within an electricity network. Effective management of these assets – from initial specification, to online monitoring, maintenance and eventual replacement – is an increasingly complex task with costly implications.

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Lightning Impulse Testing of Natural Ester Fluid Gaps and Insulation Interfaces

A significant amount of lightning impulse breakdown and withstand testing has been accomplished in mineral oil to understand this important electrical characteristic for transformer insulation system design. To be considered as viable insulating fluids for high voltage equipment, alternative dielectric liquids should have similar lightning impulse characteristics as compared to mineral oil to provide the clearances necessary for common dielectric design.

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Review of Kraft paper/natural ester fluid insulation system aging

We examine the results of recent Kraft paper/natural ester fluid insulation system sealed tube aging studies. The initial rates of cellulose degradation of Kraft and thermally upgraded Kraft in mineral oil or natural esters are similar. Subsequent degradation in natural ester occurs at a slower rate. This appears to be true for both plain and thermally upgraded Kraft.

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Transformer Winding Hot Spot Temperature Determination

As part of acceptance tests on new units, the temperature rise test is intended to demonstrate that, at full load and rated ambient temperature, the average winding temperature will not exceed the limits set by industry standards. However the temperature of the winding is not uniform and the real limiting factor is actually the hottest section of the winding commonly called winding hot spot.

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Optimum Transformer Cooling Control with Fibre Optic Temperature Sensors

It is shown that in case of rapid load change, the methods used by classic WTI can indicate a lower temperature by more than 10°C even if they are properly adjusted for the steady state conditions. It appears that with the dependability of modern fiber optic sensors, the long-term performance of transformer cooling can be better achieved with these more accurate monitoring devices.

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