# Transformer Dot Convention



## mikec

Can anyone explain the dot convention used as it relates to current flow in transformers,especially autotransformers. This seems to be very confusing to me and the EERM does not do a good job explaining this in my opinion.


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## z06dustin

can you scan a pic and post it? or find one online?

should be simple enough, current flows: in the dot / in the dot, or out the dot / out the dot.


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## juan

Dot Convention

It is common in transformer schematic symbols for there to be a dot at the end of each coil within a transformer, particularly for transformers with multiple windings on either or both of the primary and secondary sides. The purpose of the dots is to indicate the direction of each winding relative to the other windings in the transformer. Voltages at the dot end of each winding are in phase, while current flowing into the dot end of a primary coil will result in current flowing out of the dot end of a secondary coil.


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## mikec

juan said:


> Dot ConventionIt is common in transformer schematic symbols for there to be a dot at the end of each coil within a transformer, particularly for transformers with multiple windings on either or both of the primary and secondary sides. The purpose of the dots is to indicate the direction of each winding relative to the other windings in the transformer. Voltages at the dot end of each winding are in phase, while current flowing into the dot end of a primary coil will result in current flowing out of the dot end of a secondary coil.



Thank you!


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## rosseria23

Good reply!


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