The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
There have been several cases of dielectric faults and failures in power transformers identified internationally that have been associated with system operation. This paper discusses UK examples and concludes the evidence indicates internal over- voltages arising from part winding resonance. These resonances are initiated by remote energisation, either intentionally or by the action of automatic re-energisation...
Hot spot temperature (HST) is the most important parameter in the operation of power transformers. The HST has to be held under a prescribed limit. HST has a considerable effect on the insulation aging. Therefore detecting, monitoring and removing the HST could be a very important and necessary action for Utilities. A new design of oil spraying and its effect, along with a thermal management in a...
For many utilities the asset base is ageing at a time when the business focus is on system availability and energy not supplied. For the major plant items, such as generators, cables and transformers, where failure leads to long term unavailability, it is important to be able to define the risks of future operation. The processes used to achieve this have many common threads across the technologies,...
This paper focuses on tapchanger control practices and settings that may cause excessive or untimely tapchange operations. Recent case study evaluations of premature LTC (Load Tap Changer) transformer failures on utility systems identified the tap changers as a major contributing factor. Common practices discussed include basic voltage control ranges and setting effects, timing options available,...
Hot spot temperature is the main limiting factor of transformer loading. On the other hand, supposing the frequency being constant, voltage increase will result in transformer over-excitation. When the transformer is over-excited, the no load loss and subsequently the hot spot temperature will increase. Thus, the transformer loading will be restricted. In this paper, the problem of loading capability...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.