Uninterruptible Power Supply Requirements
An uninterruptible power supply (UPS) is a device that sits between a power supply (such as a wall
outlet) and a device (such as a switch) to prevent outages, sags, surges, and bad harmonics from
adversely affecting the performance of the device.
A UPS traditionally can perform the following functions:
•
Absorb relatively small power surges.
•
Smooth out noisy power sources.
•
Continue to provide power to equipment during line sags.
•
Provide power for some time after a blackout has occurred.
In addition, some UPS or UPS plus software combinations provide the following functions:
•
Automatically shut down equipment during long power outages.
•
Monitor and log power supply status.
•
Display the voltage (current draw) of the equipment.
•
Restart equipment after a long power outage.
•
Display the voltage currently on the line.
•
Provide alarms on certain error conditions.
•
Provide short circuit protection.
Selecting a UPS
To determine UPS requirements for your switch, answer these questions:
•
What are the amperage requirements?
•
What is the longest potential time period that the UPS would be required to supply backup power?
•
Where will the UPS be installed?
•
What is the maximum transition time that your installation will allow?
Note
We recommend that you use a UPS that provides online protection.
Calculating Volt-Amperage Requirements
To determine the minimum volt-amperage requirements for your UPS:
1 Locate the voltage and amperage requirements for each piece of equipment. These numbers are
usually located on a sticker on the back or bottom of your equipment.
2 Multiply the numbers together to get Volt-Amps (VA):
VA = Volts x Amperes
3 Add together the VA from all the pieces of equipment to find the total VA requirement.
To determine the minimum volt-amperage requirements for your UPS, we recommend that you add
30% to the total.
Site Preparation
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