Ferrite Transformer Testing
As electronic products utilise higher frequency techniques to reduce size and improve efficiency, ferrite cores are used in an increasing proportion of transformer designs. Transformer manufacturers must therefore meet a need for smaller transformers designed to operate at higher frequencies, which introduces additional demands on both manufacturing and testing methods.
These issues apply to a wide range of common applications including switched mode power supplies, lighting ballasts, inverter drives, audio and telecommunications equipment and many more. Today's need for the proven performance of all components within a product has resulted in a demand for each and every transformer to be more thoroughly tested than traditionally expected. In the following pages, we will consider the range of tests that are appropriate for thorough testing of ferrite transformer designs and we begin with a review of the components present in a common transformer.
Schematic of a simple two winding transformer connected to the four wire Kelvin nodes of an AT series transformer tester.
From the schematic in figure 1, it can be seen that even the most simple of transformers includes quite a complex combination of resistive and reactive components. In order to establish with confidence that a transformer has been manufactured correctly, it is necessary to execute a range of tests that combine to provide an assurance that the materials used and manufacturing process executed results in transformers that meet the design specification.