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Strange transformer fault.

Have been using some 300va 2x12v output tx,s to supply heated takeaway bags.The two outputs are marked 0 and 12v each,so am linking

0-0 and 12v-12v to give a single 12v output.Out of a batch of 20txs this works fine,but on 2,the 5A primary fuse blows as soon as the

secondarys are linked.Could this be caused by one of the 12v windings being in the opposite direction to the rest of the batch?

                                                                                                             Thanks for any advice,

                                                                                                                         Regards,

                                                                                                                               Hz

                                                                          

                                                                                               

                                                                                                         

  • Is this of any use?


    Using Power Transformers In Parallel or In Series - Bing video


    Z.
  • Some Tx are ok to para but some are not (due to coil matching I think) a check with the maker might help
  • Thanx Zoom and Ebee,interesting video,and looks like secondarys not identical on some of the batch,or out of phase.

                                                                                                                                Regards,

                                                                                                                                       Hz.
  • Have been using some 300va 2x12v output tx,s to supply heated takeaway bags.The two outputs are marked 0 and 12v each,so am linking

    0-0 and 12v-12v to give a single 12v output.Out of a batch of 20txs this works fine,but on 2,the 5A primary fuse blows as soon as the

    secondarys are linked.Could this be caused by one of the 12v windings being in the opposite direction to the rest of the batch?

    Yup - sounds like one set of terminals have been reversed (could be either the primary or the secondary) - in normal circumstances it doesn't matter so the manufacturer probably isn't that careful. It should be easy enough to measure the voltage difference between the final pair of of secondary terminals before you connect them - and just reverse the connections to one winding if it shows 24V rather than 0V.


       - Andy.