What Is A Transformer Tap Changer - Miracle Electronics

1. A tap changer is a device fitted to a transformer to regulate the output voltage to the required level. This is done by changing the turn ratios of the transformers by connecting to a number of access points known as ‘taps’ along either the primary or secondary winding. These tap changers are generally placed on low-current high-voltage transformersto minimize the current load during operation. Tap changers exist as two types – no load tap changers, and on load tapchangers. What are no load tapchangers? No load tap changers are used where a transformer’s turn ratio does not require frequent changing. The tap point in such a case may take the form of a transformer connection terminal, requiring the input line to be disconnected, and then connected to the new terminal. Alternatively, the process could also be assisted by means of a rotary or slider switch. These tap changers must be de-energized before the turn ratio is adjusted. What are on load tapchangers? On load tap changers generally consist of a diverter switch and selector switch that operate togetherasaunittotransfercurrentfromonevoltagetaptothenext.Thesetapchangers

2. adjust their turn ratio during operation. This tap selection is made via an automatic system for on load tap changers, and manually for no load taps changers. More than 95% of power transformers in Indiaabove 10MVA incorporate on load tap changers for regulating their voltage. How are tap changers fitted totransformers? The tapped portion of the winding could be located at the end of the winding, in the middle of the winding, or at the beginning, depending upon the type of winding. However, the most popularly used set-ups are those in the middle or at the beginning of the winding, as they provide the least electrical stress between the tap changer and the ground. Moreover, the tapings are subject to less physical and electrical stress from fault current entering the line terminals in suchset-ups. Another consideration is whether the tap changers should be connected to the primary or secondary windings of the transformer. Well, it can be connected to any of the two depending upon various factors like the type of transformer winding, position of tap changer in the winding, transformer’s current rating, size, cost, insulation levels, step voltage, circulating current, and losses associated with different tap changerconfigurations. While working with tap changers, it is important to understand that a duplicate circuit is provided so that the load current can be carried by one circuit while the other carries out switching, and also that some form of impedance is present in tap changers to prevent short circuiting of the tapped section. This impedance could be resistive or reactive. Tap changers with resistive impedance use high speed switching, and those with reactive impedance use slow moving switching. You can get the best-in-class power transformers in Indiafitted with the best quality tap changers for effective functioning, at Miracle Electronics, the leading transformer manufacturer inIndia. For more information visit: MiracleElectronics