Voltage closure test for transformers

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[/fusion_code][fullwidth backgroundcolor=”” backgroundimage=”” backgroundrepeat=”no-repeat” backgroundposition=”left top” backgroundattachment=”scroll” video_webm=”” video_mp4=”” video_ogv=”” video_preview_image=”” overlay_color=”” overlay_opacity=”0.5″ video_mute=”yes” video_loop=”yes” fade=”no” bordersize=”0px” bordercolor=”” borderstyle=”” paddingtop=”20px” paddingbottom=”20px” paddingleft=”0px” paddingright=”0px” menu_anchor=”” equal_height_columns=”no” hundred_percent=”no” class=”” id=””][title size=”1″ content_align=”left” style_type=”single” sep_color=”” class=”” id=””]How to perform a Voltmeter closure test[/title][youtube id=”GZ2231WM3g0″ width=”600″ height=”350″ autoplay=”no” api_params=”” class=””][fusion_text]

How to avoid blowing yourself up when paralleling transformers

When you are paralleling transformers it is imperative that you observe the proper instantaneous polarities for both transformers. If you don’t you run the risk of experiencing Kablazalflam (Ancient dutch for blow your face off).

Trust me this is not good.

I have seen some students not pay attention and let all the smoke out of the transformers. Trust me there is a lot of smoke in there. This video will help you learn how to use a voltmeter to determine whether or not it is safe to make the final connection on the last transformer.

So what do I do?

Remember a few things:

It is all about the polarity.

You determine the primary instantaneous polarity.

The line polarity determines the primary polarity.

The primary polarity determines the secondary polarity (H1 and X1 are always the same polarity)

Ok, I did all that now what?

Make your connections, but before you make your final connection use a volt meter and test between the transformer and the final connection point. If all is well you should read a very low voltage (almost zero).

If you have somehow mixed up polarities then you will read twice the voltage you would expect to read. This is because the flux from both transformers is adding. For example if you were paralleling two 480-120 Volt transformers and you did not pay attention to polarities and hooked them up wrong, you would read 240 Volts (120 V + 120 V). This is not good.

In conclusion

I can not stress enough the importance of finding your winding ratings and instantaneous polarity (See my post on winding ratings here). Once you have those all figured out the rest is easy.

Just watch the video to see what I mean.

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