This document outlines the design standards and requirements for TSEU. 02 - Design Standards for Electrical Substation Layout and Configuration. It is intended to establish safety guidelines for. and "secondary essential services". Examples of equipment for maintaining conditions of habitability are given in Pt 6, Ch1, 101. ”Can't find the product you need? Please give us feedback Dongfeng-covering various types of distribution boxes_rich and diverse product system, covering various types of distribution boxes and cabinet products. The PI value is calculated as the ratio of insulation.