What does derating mean in relation to a power supply?
Derating is the reduction of the maximum output power, depending on the environmental conditions. It is a recommended protective measure for power supplies. It protects them from excessively high temperatures and prevents system failures.
For example, derating a power supply may be required in the case of:
- low input voltage
- high temperatures
- very low temperatures
- mounting orientations that differ from the standard
- altitudes higher than 2000 metres above mean sea level
An alternative to reducing the power in many cases is a reduction in the maximum permitted ambient temperature or the use of forced ventilation.
Power supplies do not derate automatically. Users have to adjust the device to the environmental conditions of their application when it is installed. This can help to prevent damage to the power supply and system downtime. Exceeding the permitted power for a short time does not generally cause any problems, but over longer periods it can lead to a thermal shutdown.
The details of the necessary derating settings can be found in the datasheets of all PULS power supplies. The derating curves are also helpful for adjusting the output current in relation to the temperature and altitude.
