Using this view we can review the advantages and disadvantages of the fan airflow direction.įigure 3: Electrolytic capacitors and fan location The loss of capacitance due to excessive heat may manifest itself in oscillation on the output voltage, random shutdowns and a failure to restart after a power loss.Ĭomparing airflow direction on heat sensitive componentsĪs an example, we are taking the TDK-Lambda 1000W RWS1000B enclosed power supply (Figure 2) which has an internal fan and an option for reverse airflow.įigure 2: TDK-Lambda’s 1000W RWS-B AC-DC power supplyįigure 3 shows the RWS-B’s fan and electrolytic capacitor locations with the cover removed. They are also used in the output filter (secondary) circuitry to reduce high frequency ripple and in the control circuitry. Every 10 oC rise in a capacitor’s temperature will halve its operating life, therefore cool air has to be directed accordingly to avoid early field failures.Ĭapacitors on the input (primary) section are used to store energy to allow the product to continue operating during brief (typically 10 to 20 milli-seconds) losses in the AC power. Electrolytic capacitors are used for multiple functions inside a power supply and their lifetime is very dependent on their case temperatures. The physical positioning and direction of the fan inside an enclosed power supply is a decision taken early during a product’s development. Ducting may be used to vent the air outside to reduce air conditioning costs. It is standard with most large racking systems to extract heat out of the system utilising fans mounted on the top or rear of the system cabinet. Primarily, this to avoid hot air being blown directly at an operator or technician, which can cause discomfort.
#Fan airflow direction series
Rack mounted equipment like the TDK-Lambda Genesys+ series of DC programmable power supplies (Figure 1) have cool air drawn in from the front of the unit and the hotter air exiting out of the rear. What determines the direction of a standard product’s airflow will be how the product is to be used, its mechanical construction, operating environment, internal back pressure and reliability. This will minimise back-pressure issues, which can stall the power supply fan and cause overheating. This may be of interest to the user when the system and power supply airflow are in different directions. The option to have the power supply manufacturer reverse the direction of the fan may be available. With integral, built-in fans some power supplies have the fan blow cool air into the power supply and others have the fan extract the hot air.
0 kommentar(er)
