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'Polarity' describes the sense (direction) in which the voltage (not current!) induced into secondary winding is acting, relative to the sense in which the voltage applied to the primary winding is acting.
In North America, a transformer's high-voltage winding terminals are identified by the letter H, and the low-voltage winding terminals by the letter X. In the case of a two-winding transformer, the pair of high-voltage terminals are marked H1 - H2, and the pair of low-voltage terminals are marked X1 - X2.
When the potential of HV terminal H1 'goes positive' (i.e. during the first half-cycle of AC), if LV terminal X1 also goes positive at the same time, then the transformer is an 'additive polarity' transformer. On the other hand, if terminal X2 goes positive at the same time as H1, then the transformer is a 'subtractive polarity' transformer.
Knowing the polarity of a transformer is very important if you intend to operate Transformers in parallel with each other (there are other factors, too, of course), in the same way as it is important to know the polarity of a battery before you can connect it in parallel with another battery.
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ViviThe sense, or direction, in which the secondary voltage acts in comparison with the primary voltage. In North American terminology, if, at the instant when terminal H1 (high voltage) goes positive, if terminal X1 (low voltage) also goes positive, then it is a additive-polarity transformer. But if X1 goes negative, then it is a subtractive-polarity transformer.
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What happen when the polarity of transformer reversed?
You cannot 'reverse' the polarity of a transformer -it is either wound with 'additive polarity' or 'subtractive polarity', and there's not much you can do about it! For a single transformer, its polarity doesn't really matter. But if you are going to parallel two transformers, then you must know the polarity of each transformer in order to avoid harmful circulating currents in their secondary windings.
Why the polarity of transformer is important?
a polarity test is a test which use to check the polarity of tranformer.the rision of this test to running the two or more transformer in parallel.like bettry situation or to fin the terminals
What will happen if the transformers working in parallel are not connected with regard to polarity?
when two transformer are connected in parallel condition,and the polarity of transformer are opposite to each other then a large circulating current flow through out the winding,therefore a very small current flow thro, the load .therefore lifespan of transformer will be reduced.
Is polarity important with fluorescent under cabinet lights?
Yes, polarity is always important. Many under cabinet fluorescent fixtures are small enough to use a small transformer rather than a ballast. But even then, the transformer will have a longer life if it's wired with correct polarity.
What is the use of polarity test?
I will assume that your question is in reference to CT and transformer polarity.In the case of a CT (Current Transformer) they have to be installed in the correct direction for proper metering. The polarity check is used to verify that they are installed correctly and that the polarity marks are correct (if the CT has them).In the case of a transformer there are two types of polarity, additive and subtractive. If you are paralleling transformers you have to ensure that they are the same type polarity in addition to other attributes.Hope this helps.Alternative AnswerIn a new electrical installation, a polarity test is conducted to ensure that socket outlet terminals are correctly wired (line really is line, neutral really is neutral, and the protective conductor (earth/ground) really is protective conductor. It's also important, for example, that the centre pin on an Edison Screw lampholder is connected to line, and not to neutral.
