Unused floating auxiliary coil left in transformer

[cupoftea]

Hi
We did a 70W PFC’d Flyback for driving LEDs. Transformer was 26:16:5 (Pri:sec:aux)
The sec is sandwiched by the pri…and then the Aux winding is on top (outer).
The thing is , we changed our mind, and never used the auxiliary winding in the end…..but just left it in the transformer anyway…just left it floating in there.
Would this cause any deleterious effects to EMC or whatever?

The product passed all its testing, including rad and Cond EMC, and thermal testing etc.

 

[Easy peasy]

you have answered your own question.

 

[cupoftea]

Thanks, just wondered if it may have made EMC worse even though it passed?.....i mean, should we really have connected one of the ends of the aux coil to primary ground?...so it acted like a shield?.....i mean, its a bit of a moot point now i agree....but...
I mean , surely with it floating, it is acting like a loop antenna?

 

[wwfeldman]

i suggest that you tie one end to common, or ground, or some known voltage so
the aux winding isn't floating. you might also put a resistor across it, even though it
is a waste of energy