One from menu A, one from menu B: optimising NEMA TP 1 transformers for process industry substation service

The National Electric Manufacturing Association (NEMA) has established a voluntary efficiency standard under which NEMA Class I transformers are required to meet certain efficiency standards as set forth in their specification TP 1-2002. This article examines the question: what should be the specification wording to insure that the furnished equipment meets NEMA TP 1 and also is optimized in terms of cost effectiveness for the application?.