Description:

Basic Concept: Atmospheric pressure refers to the atmospheric pressure acting on a unit area, numerically equal to the gravitational force on a vertical column of air extending upward to the upper boundary of the unit area. The unit of measurement is Pascal (Pa). As defined above, atmospheric pressure gradually decreases with increasing altitude in the natural environment. At an altitude close to 5,000 meters, the atmospheric pressure drops to about half of the standard atmospheric pressure at sea level. At an altitude close to 16,000 meters, it drops to about one-tenth, and at an altitude close to 31,000 meters, it drops to about one-hundredth. Atmospheric pressure at the same altitude is also affected by temperature and latitude. Temperature affects the movement of gas molecules in the atmosphere, and higher temperatures result in more vigorous motion, thereby increasing atmospheric pressure under other equivalent conditions. Different latitudes are subject to different centrifugal forces exerted by the Earth, and lower latitudes experience stronger forces, resulting in higher atmospheric pressures under other equivalent conditions.

Purpose: Mainly to determine the environmental adaptability and reliability of instruments, electrical products, materials, components, and equipment under low pressure, high temperature, low temperature, either individually or combined, and to measure electrical performance parameters when the test specimen is energized.

Scope of Application:

Aviation, aerospace, information, electronics, and other fields.

Effects of Low Pressure:

Effects of Low Pressure on Products: The direct impact of reduced pressure on products is mainly due to the pressure effect caused by pressure changes. For sealed products, the external casing may experience pressure, which poses a risk of seal damage. However, the main effect of reduced pressure lies in the significant impact on product performance due to the associated decrease in atmospheric density. For heat-generating products such as motors, transformers, contactors, resistors, etc., these products generate heat during operation, causing an increase in temperature referred to as temperature rise. The temperature rise of heat dissipation products increases with the decrease in atmospheric pressure and the increase in altitude. This leads to a decline in product performance or the occurrence of unstable operation. For equipment that uses air as an insulating medium, low pressure has a more significant impact. Under normal atmospheric conditions, air provides good insulation, and many electrical products rely on air as an insulating medium. In regions of high altitude or when used in airborne equipment, due to the reduced atmospheric pressure, localized discharge phenomena called corona occur near high-voltage electrodes, and in severe cases, air gap breakdown may occur. Under low pressure, especially in conjunction with high-temperature conditions, the dielectric strength of air significantly decreases, resulting in lower corona inception voltage and breakdown voltage, thereby increasing the risk of surface discharge or corona discharge.

Image of High Altitude Low Pressure Testing Equipment: