Spacing Between Substations and Liquid-Type Transformers: How Close is Too Close?

Substations exist at every petrochemical facility, from the incoming power high-voltage substation and switchyard through all levels of distribution downstream. Typically, large liquid-type transformers are located near these substations to step voltages down to levels required by process units and other loads. This article examines current industry standard requirements and recommendations, fire considerations, and best engineering practices used when installing new liquid-type transformers and retrofilling existing liquid-type transformers with different types of dielectric liquids. The scope of this article is limited to in-plant power distribution outdoor transformers that have secondary voltages ranging from 480 V to 35 kV and are limited to installations subject to ANSI/National Electrical Manufacturers Association codes and standards.