Version: 02/02/05 Page 14 of 22
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Over Current Fault – The load is drawing more current than the 802.3af specification of
350mA. This also applies to Legacy devices.
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Over Power Fault - The load is drawing over 1 watt more than either the 802.3af
Classification amount or the Max Port power setting.
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Short Circuit – The system has detected a signature resistance of less than 3K.
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Start Up Fault – The load is drawing too much current too quickly in the detection
process. This fault is usually only associated with certain Legacy devices, but could
occur with a defective 802.3af device.
13. Power Availability
The PH24DC/NN, PH12DC/NN, PH12/NN, and PH6/NN models can provide the full 802.3af
15.4 watts per port for all ports.
The PH24/NN can provide 15.4 watts per port for up to 14 ports or up to 9 watts per port for all
24 ports. The following information pertains to the PH24/NN models only.
As devices are connected, the PH24/NN will allocate power to that port based on one of two
methods. Method 1 is the IEEE 802.3af Device Classification system. Each 802.3af compatible
device will have one of the four classifications as defined in the following table.
Class
Minimum PSE Output Power
Class Description
0
15.4 watts
Unknown Power
1
4.0 watts
Low Power PD
2
7.0 watts
Medium Power PD
3
15.4 watts
Full Power PD
The second method is the “Max Port Power” setting on the Port Status and Configuration web
page. The “Max Port Power” can be set from 1 to 15 watts in 1 watt increments. This setting is
only valid for 802.3af Class 0, Legacy, and Forced On modes. For Class 1, 2, and 3, the Juice
Box will meet the 802.3af specification for minimum output power for the detected device
class.
The PH24/NN will allocate power to newly connected devices until all 220 watts have been
allocated. If the next device connected would require the PH24/NN to allocate more than 220
watts, then that device will not be powered.
These features allow the PH24/NN to provide power to more devices, since the system can
allocate less than the maximum to any one device. If all ports are configured for maximum
