Electrical Design of Electrothermal Heating Engineering

Li Gang（Xinjiang Wind Architectural Design & Research Institute Co., Ltd., Urumchi 830002，China）

Abstract Due to the fact that the branch of electrothermal heating system is usually single-phase powered, the phase sequence must be distributed evenly with max. phase load current not over 115 % of mean value and min. phase load current not less than 85 % of mean value. It is found by investigation that the design drawings for a project appear to be three-phase balanced, however, bigger deviation is available during operation because of time / zone devision operation of integrated control system for computer netwrok and poor combination of phase sequence during programming.

Key words　Electrothermal heating system Demand factor Power factor Temperature controller Insulation resistance

摘　要　电热采暖系统分支回路一般为单相配电，因此在相序分配时一定要保持均衡，最大相负荷电流不宜超过平均值的115 %，最小相负荷电流不宜小于平均值的 85 %。调研发现某项目设计图看起来三相平衡，但由于计算机网络集中控制系统分时分区运行，编程没有注意相序组合，造成运行时存在较大偏差。

关键词 电热采暖系统 需要系数 功率因数 温控器 绝缘电阻