Operation of MEAN WELL power supplies in various environmental conditions

The choice of a power source, taking into account the operating conditions of the ambient temperature (at the location of the power source) and humidity, is the key to its reliable and long-term operation in compliance with technical characteristics and parameters. Therefore, it is important both to take into account the environmental conditions and, if necessary, to use additional solutions to improve them, taking into account the recommendations of MEAN WELL.

One of the main environmental characteristics is the permissible operating temperature range of the power supply, which is always specified in the Power Supply Specification. Explanations are provided on a special graph of the dependence of the output power on temperature (Derating Curve):

Graph of the dependence of output power on temperature using the example of the NDR-120 series

As can be seen from the graph, when operating the power supply in temperature boundary conditions (at very low or, conversely– very high temperatures) The maximum load capacity must be reduced. Using the example of NDR-120 series power supplies, the maximum load power should not exceed 50% of the rated power level at a temperature (at the location of the unit) close to +70°C. It is important to emphasize that it is not just the outdoor ambient temperature that is indicated, but the temperature in and around the power supply location. Due to the power supply's own heating, the temperature in the location will always be higher, and sometimes significantly higher than the outdoor temperature, and the difference can reach tens of degrees Celsius.

There are a number of manufacturer's recommendations for operating switching power supplies at low temperatures (below zero Celsius).:

• The preferred mode of operation of the power supply when the load is switched off is standby mode, that is, external power is supplied to the power supply unit, and the load is disconnected from the output. In this case, the power supply will be idling and heating itself.
• An external heater can be used to increase the temperature at the location of the power supply.
• It is also preferable to reduce the output load capacity.

One of the important conditions for compliance with the technical characteristics and better cooling of the power supply is its proper placement. Thus, power supplies for installation on a DIN rail (for example, the HDR series) must be installed directly on a DIN rail of the appropriate width – only in this case will proper ventilation and cooling of the power source be ensured. The manufacturer specifies unacceptable placement methods in the documentation.:

Unacceptable ways to place power supplies on a DIN rail

Housing-type power supplies, such as the popular LRS or RS series, can be installed vertically (on an edge), but on condition that additional space is provided on the three remaining sides for air flow. A similar requirement is for a multi–unit power supply system - there must also be an additional ventilation space between them.:

Housing-type power supply placement conditions for better cooling

MEAN WELL general recommendations for ensuring the best possible cooling of power supplies during operation:

• Each power supply unit must be installed in places with proper ventilation, for example, installed in places with good ventilation or inside enclosures with a vent at the top.
• The correct direction and location of the installation, that is, it is preferable that the ventilation openings are directed upwards (since the heated air always rises).
• Each power supply unit must have a corresponding radiator (for example: if a switching power supply uses a housing as a radiator, make sure that the housing fits snugly against the metal surface of the system).
• When multiple power supplies are running at the same time, it is necessary that there is enough space between them. Depending on the output power, the distance should be from 5 to 15 cm.
• The use of forced airflow can effectively improve heat dissipation. For example, you can add a fan and install it at the bottom of the system to provide draft for the incoming air flow. Alternatively, you can install it at the top of the system to extract heated air.

For more information on the technical characteristics and operating conditions of power supplies depending on temperature and humidity, see the Specifications on the product page. For advice or clarification of information on MEAN WELL power supplies, please contact the email address Meanwell@chipdip.ru .