The Poe Provision Process - Interlogix IFS NS3601-24P User Manual

When to install PoE?
Consider the following scenarios:
• • You're planning to install the latest VoIP Phone system to minimize cabling building costs when your company moves into
new offices next month.
• • The company staff has been clamoring for a wireless access point in the picnic area behind the building so they can work
on their laptops through lunch, but the cost of electrical power to the outside is not affordable.
• • Management asks for IP Surveillance Cameras and business access systems throughout the facility, but they would rather
avoid another electrician's payment.
References:
IEEE Std 802.3af-2003 (Amendment to IEEE Std 802.3-2002, including IEEE Std 802.3ae-2002), 2003 Page(s):0_1-121
White Paper on Power over Ethernet (IEEE802.3af)
http://www.poweroverethernet.com/articles.php?article_id=52
Microsemi /PowerDsine
http://www.microsemi.com/PowerDsine/
Linear Tech
http://www.linear.com/

The PoE Provision Process

While adding PoE support to networked devices is relatively painless, it should be realized that power cannot simply be
transferred over existing CAT-5 cables. Without proper preparation, doing so may result in damage to devices that are not
designed to support provision of power over their network interfaces.
The PSE is the manager of the PoE process. In the beginning, only small voltage level is induced on the port's output, till a valid
PD is detected during the Detection period. The PSE may choose to perform classification, to estimate the amount of power to
be consumed by this PD. After a time-controlled start-up, the PSE begins supplying the 48 VDC level to the PD, till it is
physically or electrically disconnected. Upon disconnection, voltage and power shut down.
Since the PSE is responsible for the PoE process timing, it is the one generating the probing signals prior to operating the PD
and monitoring the various scenarios that may occur during operation.
All probing is done using voltage induction and current measurement in return.
Figure 8-2 - Power Supplied over the Data Pins
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User's Manual of NS3601-24P/4S Series