Mitel 5560 IPT none Specifications download pdf (Page 110)

Engineering Guidelines

Cable Power Loss

Some power loss will occur over the Ethernet cable used to connect the phone to the L2 switch

or the mid-span powered hub.

If you are using an IEEE 802.3af compliant L2 switch or mid-span power hub and the power

required by the telephone does not exceed 8 W, the power loss in the cable will be approximately

10% of the power required by the phone.

The IEEE 802.3af standard specifies that the PSE must provide at least 15.4 W and that the

PD cannot draw more than 12.95 W maximum. The difference between these two figures is

intended to allow for cable power losses over 100 m of Category-5 cable when a PSE is powering

a PD that draws that maximum allowable power.

In other words this means that under worst case conditions the cable power loss will be 19%

of the power required by the phone.

The CXi and CXi II total power budget of 100 W takes power losses incurred over cables into

account. There is no need for the installer to manually de-rate the 100 W power budget.

The above guidelines are not applicable if you are using a PoE L2 switch that is not IEEE

802.3af compliant.

Power Management Features in IEEE 802.3af Compliant Switches

Some innovative vendors of IEEE 802.3af compliant switches, such as Hewlett Packard and

Mitel, provide power management features that can help to manage a situation where a group

of phones might require more total power than the L2 switch can provide. For example:

• Dynamic Power Distribution: If some phones do not require maximum power the switch will

re-distribute the unused power to other phones that may require more power.

• Power Prioritization Per Port: This mechanism allows certain ports or ranges of ports to be

deemed “critical”. Power to phones connected to critical ports will be guaranteed, phones

connected to ports that are not deemed critical may not receive power if the power capacity

of the L2 switch has been exceeded.

For details on specific L2 Switch capability and how to configure port power prioritization refer

to the L2 switch documentation.

Phone Power Consumption

This section provides tables with information on telephone power requirements. Use the table

that is relevant to your particular installation.

Local power

Table 34 below lists the actual power required by the various telephones. The values in this

table can be used to determine:

1 2 ... 105 106 107 108 109 110 111 112 113 114 115 ... 380 381

No comments

Mitel 5560 IPT none Specifications Page 110