IEC connectors at elevated ambient temperaturesFollow article
The maximum permissible pin temperature (cold = 70°C, warm = 120°C or hot = 155°C) determines the appliance inlet classification. Pin temperature is measured at the base of the pin. As well as the ambient temperature, the temperature of the pin is also influenced by the temperature reached when in the appliance is in use.
However, the temperature of the pin is by no means always the limiting factor. Almost always the limiting element is the insulating material of the housing of the connector.
The insulating material used in SCHURTER connectors is specified in the list attached along with the respective certified Relative Temperature Index for electrical stress (RTIelec), in accordance with the respective UL Yellow Card. This value indicates the ageing temperature that a material can withstand over a period of 100,000 hours while still retaining at least half of its original material properties (in this case its dielectric strength).
Fig. 1: The virtual volume is to be taken as the area around the installation socket in question with an ambient temperature of T42.
The RTIelec reduced by the rise in temperature ΔT provides the upper limit for the ambient temperature T42 in which a safe operation is ensured.
RTIelec- ∆T= T42
The rise in temperature ΔT is calculated by the maximum temperature measured at the hottest point Tb within the appliance coupler - depending on the current flow - minus by the ambient temperature T42.
Tb- T42= ∆T
This means: Depending on the maximum occurring ambient temperature and the period in which the appliance coupler is subjected to elevated temperatures, use can also be regarded as uncritical at operating temperatures that exceed the specification listed in the appliance inlet standard.
The following derating curves for specific SCHURTER connectors show the maximum recommended ambient temperature T42 with respect to the current applied.
Fig. 2: Derating curves for selected SCHURTER outlets Type F (IEC 10 A / UL 15 A)
Fig 3: Derating curves for selected SCHURTER outlets Type J (IEC 16 A / UL 20 A)