High Power PoE Test Drive

Today’s lab work included testing the combination of the Microsemi (Power Desine) PD-7001G 30 watt mid-span PoE power injector and the same company’s PD-AS-701/12 30 watt high powered PoE splitter. These devices are well suited for use with cameras like the Axis 215 PTZ which require less than 25 watts but more than the 12 watts available from 802.3af systems.

Our real-world testing included a pair of the above devices plus a Kill-A-Watt AC power meter, a 12 ohm 50 watt load resistor, a DC ammeter and a DC voltmeter. Results as follows

AC Power – 15W @ no load, 30W @ full load
AC Volt-Amps – 27VA @ no load, 48 VA @ full load
DC Voltage 12VDC @ no load, 11.85VDC @ full load
Load Test Current 1.85 amperes
Load Power 21.9 Watts
Overall efficiency 73%
Injector Final Case Temp ~100F
Splitter Final Case Temp ~120F

These devices require free air flow and should not be buried under any type of insulation or barrier. The power available is more than sufficient for the Axis 215. Here is a good table of applicability of high power PoE to various Axis cameras. This table suggests that the 701/24 can provide power for the even larger 232D+ or 233 PTZ cameras. Do bear in mind it will NOT run the heater/blower in an outdoor dome.

RAID 5 May Be Doomed in 2009

A story appearing online is forecasting the doom of RAID 5 in 2009. Apparently with storage capacities of modern SATA hard drives now reaching 2-terabytes in size, the odds of a read error during a RAID 5 disk reconstruction is becoming unavoidable.

Power over Ethernet – Plus

Most new IP based security cameras allow for Power over Ethernet (PoE) operation and this is now established as a way to reduce installation cost while improving reliability and easing management’s job. Since 802.3af PoE is limited to about 12 watts maximum load, the operation of PTZ cameras is generally considered beyond the scope of the method. While the pending higher powered 802.3at standard is still but a future promise, all is not lost.

Many of the newer PTZ cameras (such as the Axis 215) can be run on DC power and require less than 25 watts. There are several companies (such as Power Designs and Phihong) that offer external (midspan) power injectors and splitters that can easily deliver enough power for such cameras.  The site Power Over Ethernet is a good resource for information on this equipment.

We have completed several project designs using these high powered PoE systems with good results and large savings in installation costs.  Keep this idea in mind for your next design or installation.