UPS cooling fan and its role in UPS system

UPS function

When the mains power input is normal, UPS will provide mains power to the load after the load is stable. At this time, the UPS is an AC voltage stabilizer, which also charges the batteries in the machine; When the mains power is interrupted (emergency power failure), UPS will immediately supply 220V AC to the load by switching the inverter to keep the load running normally and protect the load software and hardware from damage. UPS equipment can usually provide protection against too high or too low voltage, and has gradually developed into a power protection system with the functions of voltage stabilization, frequency stabilization, filtering, anti electromagnetic and radio interference, anti voltage surfing, etc.

Why UPS is hot

UPS operates in different modes and generates different heat. Most of the working time, UPS works in the state of main circuit inverter, and the working efficiency reaches 80%~98%. 2%~20% UPS power will be converted to heat. UPS 100 kVA can generate 5 kW~10 kW of heat. Due to external factors such as heat dissipation, UPS reduces the capacity utilization efficiency. It is also common for large UPS to have many electrical components, large heat loss, and performance lower than 95%. This means that 5% to 10% of the power is converted into heat consumption. In addition, IGBT (Insulated Gate Bipolar Transistor) modules are widely used in UPS power supply design. IGBT module generates a lot of heat. Generally, heat is output to the system space by connecting a thermal conductive silicone lubricant (Tgreate2500, Tgreate300x) or a thermal conductive phase change material (TPCM 780SP) to the radiator.

How does UPS solve the heat dissipation problem

The ambient temperature of UPS power supply shall not be higher than 25 ℃. If the working environment temperature exceeds 25 ℃, the battery life will be shortened by about half for every 10 ℃ increase. Compared with natural convection cooling, the cooling fan has better cooling effect and can reduce the temperature in the system to 30 ℃. In the UPS system, if there is no cooling fan, the air flow rate inside the system is too low, which will cause the temperature of the components in the system to be too high. The temperature difference between the component shell and the shell exceeds 40 ℃, and there is a temperature difference of 5 ℃ to 15 ℃ from the equipment surface to the internal heat source. The failure rate of UPS components and systems will increase significantly. The forced air cooling of the cooling fan can raise and lower the temperature of 40 ℃ to below 10 ℃. Therefore, almost all UPS power levels will use forced air cooling to reduce the temperature rise of equipment.

DC fan, EC fan, CPU heat sink