Reduced Transformer Insulation

Since the switching-surge voltage, rather than the lightning-surge protection, is the predominating factor in the design and application of 2-step-down BIL transformers, further work is necessary to establish industry standards for evaluating protection under these conditions. In the meantime, added service experience with 2-step-down BIL transformers will be obtained and a successful record with these transformers and arresters will lead to more general use of reduced insulation with its associated savings to the industry.