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Ep. 2 Electrical Boss- Basics of Electrical Transformers

Basics of Electrical Transformers | How Transformers Work & How You Test Them


Today we will discuss the basics of transformers; what they are, what they do, and what they're made of. We will also do a quick continuity test and megger the transformer.


In this video we use a 5 kv a transformer that is 480 volts on the primary and it steps down to 120/240. There's a number of different types of transformers there's step-down transformers and step-up transformers. What they do is they take one voltage and either step it up to a larger voltage or they take the voltage and they step it down to a smaller voltage.


Once we opened it up you could see the coils, telling us this is a single phase transformer. There are usually only two coils that you're going to see, your high side which is your primary where the 480 volts will go then this is the low side where you get your 120 volts and 240 volts.


There are single-phase transformers, 3 phase transformers, dry type and there's oil-filled. There are many different types of transformers but in this video we used a single phase so it had the two windings, most three phases (not all) will have three windings. To get a better look we took the covers off but when you're testing the transformer you don't necessarily have to take all the covers and some transformers won't let you take all the covers. Most of them come on a simple base like the one in this video and then they have the covers around them just so it's easy if there is ever something that goes wrong with your transformer it's easy to take it out and have it serviced or rewound.


Once open, you can see the two coils and the iron cores which are connected together and the electricity goes through five separate windings on this transformer. The way the electricity travels is through electromagnetic induction and that's how a transformer works you put the electricity on the high side and it travels through these coils around the iron core and from the way that these windings are wound produces the low voltage 120/240.


We tested the transformer to make sure that everything was good and it's ready to go into service. This included a quick continuity and megger test. The continuity test is simply done with your multimeter and we used an old megger machine but you can also buy digital meggers that have a ground connection so that you don't have to wait for this to dissipate.


Following the tests we know it is a good transformer and this is something that we can sell and that will be listed on our website. There you can find our full inventory of transformers. Savona Equipment sells a lot because transformers are a piece of equipment that has no moving parts and most of the time these pieces of equipment are protected with either breaker or fusible disconnects so if there is a piece of equipment that fails that usually doesn't get back to the transformer.


You can view our full electrical inventory which includes motors, breakers, switches, and more!


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