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Connector Current & Voltage Capacity

Hi Eyeryone,

I attended a European standards meeting in London last week, which was a
good opportunity to raise the question of current and voltage capacity of
the modular connector (RJ-45). The group concerned was CENELEC TC215 WG1,
which is responsible for structured cabling. 5 connector manufacturers and
2 test houses were represented at the meeting.

Working figures of 50 Vdc and 250mA per pin were agreed at a temperature of
20degC. Please note that these are STRAWMAN values which require
confirmation by manufacturers. I would like you to consider these as
initial input to the development of a suitable remote powering scheme. In
return, I require the following information which will enable manufacturers
to conduct validation:

1.  Load reactance: we need to understand the nature of the load in terms
of inductance/capacitance. This will determine the maximum current capacity
per pin and contact life (number of insertions).

2.  Make/break current: intelligent power circuits will probably eliminate
or reduce the current when making connector contact, but will this be the
case for breaking? This is quite important.

3.  Temperature range: connector manufacturers intent to specify
performance for -10 to +40degC. Depending on the load reactance, this may
not change the current capacity. Is this sufficient?

I intend to present this to a wider audience at an ISO/IEC meeting 7-11 Feb
and would appreciate responses by this date. I am unable to attend the
802.3 interim meeting in January.


Alan Flatman
Independent Consultant