PoE - Power Supply

PoE

Mar 22

Written By Josh Varghese

Power Supply
When designing a PoE system, you will want to calculate how much power you will need. Calculating too much power can result in a larger and more expensive power supply than necessary, and it may even require a larger panel than originally specified. Underestimating can possibly damage equipment.

Traditional Calculation
To calculate the PoE Power requirement, you might try calculating with the following formula:

(PoE port quantity * port power available + PSE power requirement) + 20% buffer

Optimized Calculation
A more accurate calculation for PoE power requirement would include information about the PDs.

(PoE ports utilized quantity * port power used + PSE power requirement) + 20% buffer
Let’s say you have a PSE that supports eight ports at 30 W each, four PDs that are only 802.3af (15.4W) and four PDs that are 802.3at (30 W). We would lower our power budget by (30-15.4 W) * quantity of 802.3af PDs (4) + 20% buffer (70 W savings).

By utilizing the optimized calculation, we can save power requirements for ports that we know are lower powered.

Check out this cool video from Antaira that shows this concept!

Choosing the Right Power Supply - YouTube
Choosing the Right Power Supply Antaira Technologies

Antaira Technologies203 subscribers