Power over Ethernet

 

Each IP device also requires a power supply in addition to a data connection. Two approaches have established themselves here.

A separate low-voltage power line is very reliable and does not affect data transmission if the installation has been carried out correctly. R&M offers innovative solutions here based on a self-developed, easy-to-install 230/380 V bus system.

The main disadvantages of a separate power supply are a lack of flexibility and substantial cabling requirements. This is why a remote power supply over the data network (Power over Ethernet (PoE) or Power over Ethernet Plus (PoEP)) is becoming increasingly popular. In this method, a special switch or intermediate device (mid-range injector) transmits power to defined cable pairs with a DC voltage in the non-regulated extra-low voltage range of 48 V. The IEEE has standardized this power supply method in the standards 802.3af (PoE) for up to 15 watts and 802.3at (PoEP) for up to 25 watts. Further developments under 802.3bt are looking to extend the power range up to 50 – 100W (4 Pair Power over Ethernet or 4PPoE).

Critical factors for PoE, PoEP and increasingly for 4PPoE are the temperature increase in the cable due to power transmission (by the resistance of the copper wire) and the destruction of the RJ45 contacts as a result of sparks when unplugging under load.

R&M has analyzed both of these factors in detail: Unless specially indicated, the cable components from R&M are suitable for the use with PoE, PoEP and future 4PPoE applications. However, the planning and installation of the cabling system will have a substantial influence on ensuring the successful implementation of Power over Ethernet. To help its customers in the planning and installation of future proof cabling, R&M provides extensive information material and an useful planning tool.

 

 

Power over Ethernet Calculator

In addition to the right choice of cabling components the planning and installation of the cabling system will have a substantial influence on ensuring the successful implementation of Power over Ethernet.
To help its customers in the planning and installation of future proof cabling, R&M developed the “PoE Calculator”.

This planning tool allows the user to simulate different environmental and installation conditions and calculates the maximum allowable permanent link length according to the relevant ISO and EN standards. By changing the parameters in a “What, if ..” analysis this tool helps to realize reliable, future proof cabling systems.

With the introduction of patch cords with smaller cable diameters for high density applications it becomes vital to have a good look at these circumstances. For this reason, R&M created an additional Power over Ethernet calculator for Patch Cords. You may find it useful to calculate the temperature cable bundles may reach in different cable management systems.