The transformer.docx

The transformer Welcome to this virtual training about transformers! With this interactive Sway you can prepare yourself for the topic "The transformer". Please take your time and go through all the chapters by yourself. This will take approx. 30 minutes. You can choose your own speed and repeat cha...

The transformer Welcome to this virtual training about transformers! With this interactive Sway you can prepare yourself for the topic "The transformer". Please take your time and go through all the chapters by yourself. This will take approx. 30 minutes. You can choose your own speed and repeat chapters as often as needed. At the end, please answer a short quiz to check if you have understood everything. Have fun! Content Use and operation Construction of a transformer Different construction types Autotransformer Loaded and unloaded transformer Short-circuit voltage and short-circuit current Real transformer and efficiency Transformer calculations Summary Quiz Use and operation Did you know... that the transformer was one of the reasons, why the alternating current (AC) won the "current war"? With a transformer the voltage can be transformed and thus the energy can be transported. You want to know more about the current war? Then you will be interested in this video: The following video explains the use and operation of a transformer: 1 - Please note: This video deals with the power grid of GB, where the voltage is 230V (as in Europe); overseas the power grid voltage is 110 or 120V. Operation: 2 - Informant: Principle of Transformer | Electrical Revolution (myelectrical2015.com) A transformer only works with alternating current (AC), not with direct current (DC)! The AC supply is connected to the primary side --> the alternating current creates a alternating magnetic field --> the voltage induced by the magnetic field in the primary winding keep balance with the supply voltage (=induction law) Through the iron core the magnetic flux is conducted to the secondary side Now the secondary winding is also permeated with a changing magnetic field --> this induces an AC voltage in the secondary coil The induced voltage is the same in each turn / the induced voltage of both coils is proportional to the number of their turns = transformer ratio Construction of a transformer 3 - Informant: Inductors And Transformers Core Electromagnetic Magnetic - Core In Transformer, HD Png Download - kindpng Consists of two or more coils on a common iron core The core is built from a stack of individual sheets, with electrically insulation layers in between --> thus reducing eddy currents Primary winding = input winding --> voltage connection Secondary winding = output winding --> here is the electrical load connected Different construction forms Shell type both windings are on the middle leg, either one above the other ore side by side. Advantages: Higher efficiency More power Disandvantages: Maintenance work is very hard Forced cooling indispensable 4 - Informant: Core Type vs. Shell Type Distribution Transformers (borderstates.com) Core type the middle leg is missing, the core forms the shape of a rectangle in side view. Usually, the windings are located separately on the two outer legs. Advantages: Cheaper Easier maintenance Disadvantages: Higher flux leakage 5 - Informant: Core Type vs. Shell Type Distribution Transformers (borderstates.com) Autotransformer 6 - Informant: Tapped autotransformer - Autotransformer - Wikipedia Consists of only one coil which has one or more taps to draw the output voltage Primary coil and secondary coil are combined --> No galvanic separation Advantages: Smaller construction with the same power More efficient compared to two windings transformer Disadvantages: If a fault like a short circuit occurs on the primary side, this fault is also on the secondary side, because they are combined Area of application: Wherever deviating voltages have to be provided and galvanic isolation is not required. Loaded and unloaded transformer Unloaded transformer If no load is connected to the secondary winding, there is no load --> the transformer is unloaded In no-load operation, the iron losses are due to the small input current much bigger than the cooper losses due to the no-load current in the primary coil It does not normally exist in practice Loaded transformer If a consumer is connected to the secondary winding, it takes electrical energy from the secondary coil A current arises on the secondary side and the primary current gets bigger The currents are directed in opposite directions in the windings If the primary current flows right-handed through the coil, the secondary current flows left-handed and vice versa Transformers can be heavily overloaded for a short time Short-circuit voltage and short-circuit current Short-circuit voltage The short-circuit voltage depends on the construction of the core and the position of the coils in relation to each other High stray fluxes lead to high short-circuit voltages Stray fluxes are part of a magnetic flux which are coupled with one of the windings only, so lost from the energy transfer. Stray fluxes can be taken into account by the impedance representing their magnetic path. More stray flux, larger impedance, higher voltage drop. Short-circuit current This is the name given to the current that flows in the event of a short circuit on the secondary side and at nominal voltage supply on the primary side. It is much higher than the rated current and can destroy the transformer within a short time The short-circuit current is higher the lower the short-circuit voltage is Short-circuit proof --> Name for transformers, which are designed in such a way that they are not destroyed in the event of a short circuit Real transformer and efficiency In reality there is no loss-free transformer Losses due to resistances in the windings and parasitic capacitances Losses in the metal structure caused by scattering of the magnetic flux Eddy currents and magnetic reversal losses in the iron core This results in energy losses The efficiency indicates the ratio of the power which leaves the transformer on the secondary side and the power which flows in on the primary side. That means how much energy gets "lost". The higher the efficiency, the fewer the losses and the more efficient the transformer works. The efficiency can, because of the iron and copper losses never be 1. It is expressed in %. Formula for calculation Typical efficiency of different transfomers: Transformers with high rated power: 99% Small transformers: 80% Miniature transformers: 50% Transformer calculations The voltages, currents and the windings can be calculated with the following formula: 7 - V1 = input voltage; V2 = output voltage; I1 = current primary side; I2 = current secondary side; N1 = Number of windings primary side; N2 = Number of windings secondary side V = Voltage in Volt (V) I = Current in Ampere (A) N = Winding turn number The ratio of the input and output voltage corresponds to the ratio of the winding turn numbers of the input and output sides. Embed://<iframe width="640px" height= "480px" src= "max-height:100vh" allowfullscreen webkitallowfullscreen mozallowfullscreen msallowfullscreen> </iframe> Summary Tap here for the summary! https://sway.cloud.microsoft/oCR3MqBDy37UT9uX#content=io76bzGqkpgWEg 8 - Informant: Evaluating Transformer Designs with Electromagnetics Simulation | COMSOL Blog Spartransformatoren | TRAMAG Transformator (tiburski.de) Quiz By taking the quiz below, you can check whether you have mastered the content. Embed://<iframe width="640px" height= "480px" src= "https://forms.office.com/Pages/ResponsePage.aspx?id=eBLu7XFi00qQapPiqX7yrjwKMVWfmUNJir5Q0b5JYm1UQURUNFhCT0FUWEFKVlY5VllCRlpOU0pZRi4u&embed=true" frameborder= "0" marginwidth= "0" marginheight= "0" style= "border: none; max-width:100%; max-height:100vh" allowfullscreen webkitallowfullscreen mozallowfullscreen msallowfullscreen> </iframe> Congratulations! You have finished this training about transformer. Any questions that arise during the training sessions will be answered with pleasure! See you soon! 9 - Thank you for your attention! https://sway.cloud.microsoft/oCR3MqBDy37UT9uX#content=fdQrBHqcX6mTzH 10 - klick me