Four-Pair PoE Puts Pressure on RJ45 Contacts

What is happening
The next generation of Power over Ethernet (PoE) is coming onto the market. In four-pair PoE (4-Pair Power over Ethernet, 4PPoE) the electrical output transferred in the data network increases to up to 100 W. The current strength increases to up to 1 Ampere per twisted pair. This is paralleled by an increase in the risk of negatively impacting the RJ45 contacts in the connections. Unplugging results in disconnection sparks that can damage the contacts and lead to signal loss.

Good to know
Investigations show: The design of connectors described in the IEC 60603-7 standard should ensure that the zone where the contact is broken and where sparking may occur (separation area) is separated from the zone where the contact between the plug and module is located in normal operation (nominal contact area).

IEC 60512-99-1 is a standard which enables testing of whether an RJ45 connection is suitable for PoE and PoEP up to 30 W. IEC 60512-99-2, which is intended to cover the power range for 4PPoE, is already at the planning stage. To ensure a PoE-compliant RJ45 connection, IEC 60603-7-x and IEC 60512-99-x must be specified.

Example of good contact design, where the damage does not have any effect on the contact zone. Nominal contact area (green) is clearly separated from the separation area (red).

Example of good contact design, where the damage does not have any effect on the contact zone. Nominal contact area (green) is clearly separated from the separation area (red).

Statement
R&M has designed the RJ45 plug contacts and the gold-plated spring contacts of the connection modules in such a way that the disconnection points lie as far as possible outside the nominal contact area. This is a constructive way of avoiding signal transmission being impaired. In addition, the insulation displacement technology used in R&M plugs ensures reliable contact resistance that is low over the entire life time. Thus only a minimal amount of power is transformed to heat inside the plug. The connector does not get hot as a result of the PoE load.

R&M recommends that planners and installers working with PoE-compatible data networks pay attention to these kinds of criteria, even though they are not necessarily found in the manufacturers’ data sheets.

Please find more information in the Whitepaper and on the R&M website.



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Matthias Gerber

By Matthias Gerber

Market Manager LAN