Formation mechanism and countermeasures of dewing in the metal enclosed switch cabinet based on internet of things
ZHENG You1,2, FANG Dan dan2, WU Ying jun3, MA Li jun3
(1.School of Electronic Information Engineering, Ningbo University of Technology, Ningbo 315000, China; 
2.School of Automation, Wuhan University of Technology, Wuhan 430070, China; 
3.Ningbo Power Supply Company, Grid State Zhejiang Power Company, Ningbo 315000, China)

Abstract: Aiming at the problems of explosion accidents in closed metal switch cabinets due to the condensation of water vapour under high pressure, an online multiplex temperature and humidity collection system based on Zigbee and GPRS was developed, by which real time monitoring of humidity distribution in a switch cabinet in non operation state under different kinds of circumstances could be implemented in different weather. Real time data in different place of switch cabinets was analyzed by correlation detection. And with the assistance of FLUENT simulation, principle about dew condensation in a switch cabinet was investigated. The results indicate that moisture mostly comes from cable trench. For the reason that moisture in the bottom can hardly be evaporated form the skylight and the heaters placed in the bottom have great performance, suggestions that installing a dehumidifier and a ventilation device in the bottom of a switch cabinet, as well as ensuring the seal of cable trench to eliminate moisture and dewing are supplied.

Key words: humidity distribution; metal enclosed switch cabinet; dewing; temperature and humidity data online acquisition system; FLUENT; internet of things technique