Specifications

Power
109
Uninterruptible Power Supply (UPS)
Use uninterruptible power supplies when phones, the associated controllers, PC-based
consoles, and the LAN infrastructure need to continue to operate during a power failure. UPSs
can range from simple local battery units to larger central installations that include backup
generators. Consider the following factors to determine the type of unit to use:
• The power to be drawn by attached units
• The power output of the UPS, and its efficiency with battery capability
• The time the UPS must supply power
• The size of the unit.
Worked Example
Consider a small installation with a LAN switch and some powered phones. The LAN switch
draws 100 W and 16 attached phones draw 8 W each. The UPS has a 12 V battery of 55 AH
and runs at 70% efficiency. How long can this combination be powered?
• The output power available is 462 VAH (volt-amperes hour) (55 x 12 x 70%).
• The consumption is 228 VA (100 W + 16 x 8 W).
• The time available is 2 hours or 462 VAH / 228 VA.
America Power Conversion (APC) is a company that designs and sells UPS systems. Some
useful calculations can also be found at the APC web site:
http://www.apc.com/tools/ups_selector/index.cfm
Mitel products are listed under “VoIP Solutions.” (Although information appeared correct when
this publication was written, Mitel cannot take responsibility for incorrect information entered
or supplied from this tool.)
Notes:
1. If VoIP service must be operational during a power failure, each of the network
components must also be on the UPS.
2. The System Engineering Tool will estimate the amount of power used by each of
the cabinets in the system configuration when running the existing traffic. The
estimate does not include the power for other network equipment (L2 switches, and
so forth).
Note: Volt-Amperes (VA) is equivalent to Watts (W) if the Power Factor Correction
(PFC) of the power supply in question has a PFC value of close to 1. Most data
switches on the market today will have a PFC value close to 1.