Current-Carrying Capacity

Current-carrying capacity indicates whether an electromechanical component such as a PTR terminal block or Multi Connector system exhibits any functional anomalies or sustains any thermal damage under a specific rated current load and the relevant ambient temperature.

The component temperature should be measured as close as possible to the component that exhibits the highest temperature. In actual devices, it should also be considered that the terminal blocks or Multi Connector Systems are affected by heat dissipation of nearby additional heat sources and/or heat conduction via the circuits.

The terminal block standard EN 60998-1, the multi connector standard EN 61984 and the EN 60947-7-4 (Low-voltage switchgear and control-gear) contain various definitions in accordance with the upper temperature limit of Insulation Materials, which for PTR products is 105 °C.

For Multi Connector Systems PTR uses in this context derating curves (in accordance with EN 60512-5-2 and EN 60947-7-4) to show on a basis of the maximum number of poles for the various wire sizes the performance of the current in correlation to the ambient temperature. The allowable operating range is determined using a reduction factor of 0.8 in respect to the value of the current in the basic curve.