Custom Wound Coils and Custom Transformers

First question.  Why do our customers buy custom wound coils?  Most of our customers would prefer to buy standard catalog parts, preferably parts available from multiple sources and kept in stock.  Second question.  What distinguishes a custom wound coil, a custom transformer, or a custom inductor from a standard coil, transformer, or inductor?

An answer to the first question is “the diversity of required parameters”.  The answer requires some further explanation.  Consider the following scenario.  There are eight product designers, each from a different company.  They all need a five-volt D.C. output power supply.  Designers 1 and 2 need 1 amp of current from their power supply output.  Designers 3 and 4 need 2.5 amps.  Designers 5 & 6 need 5 amps.  Designers 7 & 8 need 10 amps.  Let’s figure what magnetic components this group of designers need.  The group needs four different switching transformers and four different output inductors.  Is that correct?  Well, no!  Designers 1, 3, and 5 will draw power from a 12-volt battery while designer 7 will draw power from a 24-volt battery.  Designers 2, 4, 6, and 8 will draw rectified power from the A.C. line, but designer 8 wants to be able to draw from either 120 or 240 volts.  Of course they all want the smallest transformer that will do the job.  They will all need different transformers.  Oh, I almost forgot.  Designers 1, 3, 5 and 7 are switching at 50 kilohertz.  Designers 2, 4, 6 and 8 are concerned about high frequency E.M.I in their applications.  They decide to limit the switching frequency to 25 kilohertz.  Now all the output inductors are different.  What other parameters could be different?  Dielectric (hipot) requirements?  Voltage regulation specifications?  Boy, what a diversity of required parts!  Do all these needed parts exist in catalogs? Doubtful!  Do the manufacturer’s keep them all in stock?  Doubtful!

Custom wound coils, custom wound transformers, and custom wound inductors can simply mean making coils, transformers, and inductors per the customer’s drawing and/or specifications.  There may be several reasons why the customer has custom designs.  Perhaps the customer could not find a suitable catalog part.  Perhaps the customer is guarding against vendor obsoleteness, perhaps against a vendor going out of business.  Alternatively, the custom coil, custom transformer, or custom inductor design may have unique features.  If so, it is doubtful that it would be listed in catalogs or be available “off the shelf”.  Another consideration is that a custom wound coil, custom wound transformer, or custom wound inductor may involve construction processes that require specialized material, equipment or handling.  High voltage coils may be one example.  Because of corona concerns, coils may have to have “void free” vacuum impregnation with epoxy, silastic, or another suitable material.  A vacuum chamber (or perhaps vacuum oven) will be required.

Butler winding can make (and has made) custom wound coils, transformers, and inductors in a variety of shapes and sizes.  This includes; various standard types of  “core with bobbin” structures (E, EP, EFD, EC, ETD, PQ, POT, U and others), toroids, and some custom designs.  We have constructed mag amps and some sensing coils.  We have experience with foil windings, litz wire windings, and perfect layering.  For toroids, we can (and have done) sector winding, progressive winding, bank winding, and progressive bank winding.  Butler winding has a variety of winding machines, bobbin/tube and toroid.  That includes two programmable automated machines and a taping machine for toroids.  To ensure quality, Butler Winding purchased two programmable automated testing machines. Most of our production is 100% tested on these machines.  Butler Winding has a corona-testing chamber for testing high voltage coils.  Butler Winding has a temperature chamber.  It can be use to temperature cycle parts.  Whatever your custom coil requirements, here is a high likelihood that Butler Winding can handle it.

Need design assistance for your custom wound coil, transformer and inductor requirements?  Please feel free to contact Butler Winding and ask to talk to Engineering. For more information on our capabilities, click on our “capabilities” link.