Selecting UPS Systems

The Uninterruptible Power Supply (UPS) that you select will depend on the type and size of load you are trying to protect. There are some critical aspects that should be considered:

First is the type and size of the Load. These factors have an impact on the type of UPS you select. Three-phase loads are unsuitable for ferroresonant systems, as are loads with large start-up or in-rush currents. The size of the unit you select should reflect not only current loads, but also plans for the growth of your system. It is important to remember that for most computers, electrical power consumption per computing horsepower is dropping every day. That means that your new computer may do more for you with less electricity.

The second thing to consider is the Installation Location. The site you select for your UPS will have an impact on the unit you purchase. UPS systems can make noise and give off heat. The line interactive units are the quietest and coolest units. They may be more suitable for office installation.

The third thing to consider is Cooling. It is important to remember that computer systems will not run if they get to hot. If you back up your computer and do not provide some means to keep the environment cool, it may trip off line, and even damage the system. Do not put your cooling system on the UPS. Instead some type of back-up generator should be used to power the cooling system.

Fourth, consider Lighting. Remember to provide back-up power for lighting in the area where personnel will bring the computer to an orderly shut down.

Fifth, remember to include Batteries. When purchasing a UPS make sure that the price of the batteries is included in your quoted price. In some cases the batteries will require their own storage cabinet, in others they will be internal to the UPS. The amount of battery time you purchase will depend on your circumstances. The most common reference point will be the length of time required to bring your computer to an orderly shut down. If you require extended run time you should consider coupling your UPS to a stand-by generator.

Sixth, consider whether you need a Stand-by Generator. If you decide to power your ups from a stand-by generator for extended run times, the generator should be at least 2.5 times larger in size than the UPS. By doing this you will avoid unit interaction problems.

Seventh, consider Installation. Some units will be plug-in systems, while others will require installation by electrical contractors. It is important to remember that the UPS will use more current than the computer system alone. This may necessitate rewiring as part of the installation.

Finally, consider the Efficiency of the UPS. The efficiency of the unit will let you know the operating costs for that unit. The higher the efficiency, the lower the operating cost.