Allied Telesis AT-x930-28GPX, Installation Manual

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Chapter 1: Overview
34
Power Budget
The power budget defines the maximum amount of power the switch can
supply to the powered devices on its ports. The higher the budget, the
more PoE devices the switch can support at one time.
The power budgets for the AT-x930-28GPX and AT-x930-52GPX
Switches depend on several factors. The first is the power supply model.
The power budgets of the five power supplies are listed in Table 3.
Note
The AT-PWR150, AT-PWR250 and AT-PWR250-80 Power
Supplies are intended for the non-PoE AT-x930-28GTX, AT-x930-
28GSTX, and AT-x930-52GTX Switches. They are not intended for
the AT-x930-28GPX and AT-x930-52GPX Switches because they
do not provide power for PoE + devices. You may install them in the
PoE+ switches, but the switches will not support PoE devices.
Another factor that determines the power budget of the switch is the
number of PoE power supplies in the device. The power budget of a PoE
switch that has only one PoE power supply is equal to the budget of the
power supply. For example, a switch that has one AT-PWR1200 Power
Supply has a power budget of 740W for powered devices.
Table 2. IEEE Powered Device Classes
Class
Maximum Power
Output from a Switch
Port
PD Power Range
0 15.4W 0.44W to 12.95W
1 4.0W 0.44W to 3.84W
2 7.0W 3.84W to 6.49W
3 15.4W 6.49W to 12.95W
4 30.0W 12.95W to 25.5W
Table 3. Power Supply Budgets of the Power Supplies
Power Supply Power Budget for PoE Devices
AT-PWR150 0 watts
AT-PWR250 0 watts
AT-PWR250-80 0 watts
AT-PWR800 380 watts
AT-PWR1200 740 watts