Do I need a UPS?

Do I really need a UPS?

How’s your power? An under-voltage of line power known as a brownout is the underlying cause in four out of five power disturbances. The remainder of the time power fails completely, but generally briefly. If you are new to your neighborhood, ask others for insight. A UPS can help by keeping equipment running normally until power returns or an orderly shutdown of equipment can be performed. Consider how much an unexpected power failure would impact your business. Note also that a one-second power interruption might result in 10 minutes downtime as equipment is restarted. Some database systems cannot tolerate un-orderly shutdown and will require lengthy recovery procedure.

Most vendors recommend a UPS be in place at least for each server machine to protect data. Check with your vendors or JCS for advice.

What size UPS do I need?

The power requirements of your computer equipment will determine the size of UPS you will need. Your first step is to decide which equipment will need UPS protection. This depends upon how well your business can tolerate a disruption in power. If, for example you are comfortable with briefly suspending operations during a power disturbance you need not consider printers, monitors and other peripheral equipment. If, on the other hand you want to continue business as usual during disturbances, then consider every piece of equipment, including modems, and network gear. You will probably need several UPSs as the equipment will be in different rooms.

The capacity of UPS units is rated in VA (Volt-Amperes) which you will probably not find anywhere on your electronic equipment. You can check how much power your equipment uses by reading the plate on the back of each device. You then need to convert that figure to VA.

If you are given the current that the device uses in amperes (A), then simply multiply the amperes by the line voltage (120V in USA) to get the VA. For example, if your appliance uses 4A, then multiply 4 by 120 and you will get 440VA.

If you are given the power in watts (W), simply divide the watts by the power factor (0.7 is generally used). For example, if your device uses 320W, then divide 320 by 0.7. This will give you 457VA.

Then simply add up the VA of all the devices that you will be running off each UPS. The next step is to add 25% to the above sum. It is highly recommended that a UPS has a capacity that is at least 25% greater than the total power capacity requirements of the connected equipment. This provides room for expansion, equipment upgrades, and allows for some deterioration of the UPS battery over its useful life.

Here's a simple example

Let's say you have a computer that uses 200W and a monitor that uses 320W that you want to run off a UPS. You would first have to add them together for a total of 520, and divide 520 by 0.7. This will give you a total of 743VA. Then add 25%, which gives you a grand total of 929VA. Your best bet would be to buy a 950VA or 1000VA UPS. Keep in mind that all the above calculations are for single phase UPS units only.

Depending on whether you are protecting many computers, or just one or two, you may decide to connect all the computers to one central UPS instead of using individual UPS units for each station. This may be more cost effective.

A UPS is not generally intended to be an alternative power supply. They are used to protect your systems by warning you of a power problem, and give you time to close down your applications and computers before the inevitable happens. Therefore, most UPS units are designed to provide about ten minutes of backup power (with small differences between manufacturers). This is usually enough time to back up what you need and appropriately shut down the connected equipment. It is advisable to look over the specifications of the UPS you are considering. If you need more time, then you must buy a larger UPS. It must be noted that buying a larger UPS does not always give you more backup time. The size and type of battery used in the UPS has a lot to do with it. UPS batteries are rated in Ah (ampere-hours). Ah represents the amount of energy a battery can hold. This measurement helps determine how long the battery will power the equipment it is used in. The more 'Ah' the longer the run time.