The substation equipment cubicle is an important part of the substation main equipment

and its safe and stable operation is critical to the reliability of the power grid. At present

in the high temperature

humidity and saltrotten climate of the southern region

substation equipment cubicle often malfunction because of the aging and rust of secondary components of internal components. The main cause of problems such as aging and rust of secondary components is that the temperature and humidity inside the substation equipment cubicle exceed the standard

which is highlighted by the condensation problem inside the substation equipment cubicle. Dew condensation is a phenomenon in which water vapor condenses on objects of relatively low temperature when it is saturated in the air

and temperature and humidity are both the main factors causing dew condensation. Based on the conservation laws of energy

momentum

mass and species

considering air as a mixture of ideal gases composed of water vapor and dry air

taking into account that the density of air changes relatively little during the flow

treating air as an incompressible fluid

a mathematical model of the temperature and humidity field model of the substation equipment cubicle under heat conduction

air convection and water vapor diffusion are constructed by computational fluid dynamics（CFD） technology with using the species transport model in order to reveal the distribution of temperature and humidity likewise the relationship between dew condensation with temperature and humidity. This paper analyzes the ef-fects of temperature

humidity

forced ventilation and internal heat source on the condensation phenomenon. The nu-merical calculation results show that the air temperature in the outdoor terminal box gradually rises under the condition of heat conduction and heat convection due to the self-heating of the conductor;The distribution of humidityshows that the humidity at the gas outlet is at the highest state

the humidity at the gas inlet is at the lowest state

thehumidity at the higher temperature is relatively lower

the humidity is relatively lower when relative humidity of theenvironment reduce

and the humidity is relatively lower when inlet gas speed increases. Finally

based on the nu-merical calculation results

it proposed that adopting a forced ventilation at the inlet

reducing the relative humidityof the environment

which can be used for anti-condensation measures.