Derate connector voltage to 25% of rated operating voltage
.... Operating voltage = Connector rating / 0.25
Derate connector operational temperature by 50oC
.... Connector rating = operating temperature + 50oC
Current is normally specified as some number of pins carrying some
specific amount of current, at some defined temperature. Normally the maximum current per pin ,or number of pins, is provided at ambient temperature. Increase the
current carried over any particular pin and the number of pins carrying
current must decrease. Decreasing the amount of current over the defined
pins may allow more pins to carry current.
2mm Hard Metric Connector
The graph above shows the derating curves for a 2mm Hard Metric connector used in cPCI and other applications. In this case the graph provides three curves;
Red Curve allowing all pins to carry current
Blue Curve allowing every other pin to carry current.
Black Curve with only alternate pins on alternate rows carrying current.
So in this case every pin on the connector can carry current [Red], but each pin is limited to 1.6 amps, or about 1.4 amps at ambient temperature. However the black curve would normally be more realistic with only a quarter of the pins carrying current. Note that all three curves fall off at the same rate and end at a maximum temperature of 125C. However each curve starts with a different amount of maximum current at 0C based on the number of pins carrying current.
Refer to this page for a manufacturers listing for Connectors
Derating guidelines for other devices; Guideline for Derating Electronic Components
These are general engineering guidlines for connector derating. Of course connectors are produced in many different shapes and styles. Connectors that are produced for backplane standards have their maximum current rating defined with the interface standard, along with the associated pins that are defined to carry current, or power.
Connectors that are used in general applications have their maximum current defined by some number of pins. The difference being a design that does not use an interface standard may end up with more pins carrying current and exceeding the maximum rating of the connector.
Engineering Key Words: Connector, Component Derating, reliability, Sizing, Derate, Ampacity, Fusing, Insulation, Rated Temp, Temperature, Guide, Guideline, Example, Class, Design.
