Transformers form a special class of components in power electronics. The design and performance of many systems are critically dependent on the design and performance of their associated transformers, and the transformer often forms the major cost item in the system. It will often pay in performance, reliability, and economy if the power electronics design engineer understands transformers and has a technical dialog with the transformer vendor. It is also a good idea to have the current IEEE C57 series of transformer standards available. These standards may be purchased from the publications department of the IEEE in a single, bound volume.

The author once served as an expert witness in a lawsuit in which a drive manufacturer sued a transformer vendor for transformers that failed in a foreign steel mill. The problem was caused by radial flux generating eddy currents in an electrostatic shield. The transformer had a full axial length primary and two axially stacked secondaries that conducted alternately. The shield overheated, the insulation failed, and the vendor was held responsible for a faulty design. Had the customer explained the service conditions to the vendor rather than relying on a standard specification, the problem might have been avoided.