If different electrical components are combined in an appliance inlet to form a power entry
module, the individual power losses and temperature deratings of all components involved
must be carefully taken into account in order to ensure long-term safe operation.
Power entry modules (PEMs) consist of a combination of components for the safe power supply of devices. In addition to the IEC appliance inlet connector, mains switches, fuseholders or circuit breakers
and filters can be integrated. All these components are tested according to their respective component standard so that the entire component can be certified by the certification bodies.
Each of these components is designed for a specific minimum and maximum ambient temperature. Important: Themaximum rated current may only be used at the rated temperature. At higher ambient temperatures, the current must be reduced accordingly. This is usually specified in the temperature derating on the data sheets.
As power entry modules are installed in a cut-out in the appliance housing, the different ambient temperatures inside and outside must be taken into account. Inside, higher temperatures are almost
always to be expected during operation, as the electrical load leads to heating (e.g. switching power supply, power semiconductors and heating elements).
Power dissipation
During operation, the components generate self-heating, which is shown as power dissipation in the data sheets. This power dissipation heats up the entire PEM and can lead to increased temperatures of all installed components.
Important here too: All components of a PEM have a nominal power dissipation, so that the sum of all power dissipations is effective in the combined element.
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