# Missed a learning opportunity today.



## kaboler (Dec 1, 2010)

My journeyman got called out to a job today, because a transformer wasn't putting out the exact voltage required. I guess fancier equipment (in this case, a big laser) requires near exact voltage.

He tells me that he can just move taps around in the voltage and it'll vary the voltage a few either way.

I've never hooked up a transformer, and I once got to look inside one, but that's it.

From what I know, voltage is due to the number of windings on 1 side vs. the number of windings on the other. So how can you move "taps"? Not entirely sure what a tap is, except to say that in my imagination, it's probably just like a water tap, but with electricity.

(turns out the shop owner had a crap multimeter).

What's a tap, and can you really adjust the voltage one way or the other a few volts, without changing the source?


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## electricalwiz (Mar 12, 2011)

the short answer is yes, if you are hooking up a transformer you can vary the output of the transformer by hooking up to different taps.


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## farlsincharge (Dec 31, 2010)

"Taps" refers to connections at different points along the winding of the transformer.


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## blueheels2 (Apr 22, 2009)

http://www.iaei.org/magazine/2001/09/overcurrent-protection-for-conductors/



Scroll down to the center of the page where you will see a pic of the inside of a transformer. Look at the windings closely and you will see what looks like studs sticking out of them. These are the different taps. It allows you to eliminate some windings or add some. Hope that helps!


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## blueheels2 (Apr 22, 2009)

http://www.powerlines.com/pqphotos.html


This is a blowup of transformer taps.


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## kaboler (Dec 1, 2010)

Ah, I see how that works. Add a few more windings, that's cool.

I should have looked closer at the transformer I looked at. I thought the load side would be comparably equal to the tap side (or whatever you want to call it).

Still, the 2nd picture has a lot more wires than I expected! These taps are smaller than I expected.

TY for the pictures!


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## Chris1971 (Dec 27, 2010)

I think Mike Holmes explained how a multi tap transformer works on the last episode of Oprah.:thumbsup:


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