Which Type of UPS System Works Best with a Generator?

(Teddi: This great content from Tripp Lite answers the most frequently asked questions about setting up power protection with a generator.) 

Do you have a generator to supply power during a lengthy blackout? You’ll get the most out of it if you connect your generator to a UPS system. But there’s more than one kind of UPS – it’s important to choose the right type of system so it will play nicely with your generator power.

Generator and UPS System Compatibility

A generator typically produces inconsistencies and fluctuations in voltage and frequency ranges. If the range is wider than what the UPS is willing to accept, your load will continue to run off the UPS and eventually deplete the batteries. This scenario would be typical with an off-line or line-interactive UPS system.

An on-line, double-conversion UPS system works differently and is the type of UPS we recommend for use with a generator. An on-line UPS continually converts incoming AC power – whether from the main power supply or a generator – into filtered DC power, and then reconverts it back into AC power with a pure sine wave. That’s the clean feed of power your sensitive equipment craves. And as another benefit, an on-line UPS filters variations in frequency as part of its everyday operation, so battery life doesn’t shorten prematurely.

When it Comes to Generator and UPS Compatibility, Size Does Matter

Your standby generator must provide computer-grade output power and be dedicated to run UPS protected IT applications only. Additionally, the continuous generator capacity rating must be at least twice the rated capacity of the UPS system used. As connected equipment cycles on and off, in rush currents can cause the UPS to switch between AC, battery and bypass modes. Over-sizing the generator relative to the UPS capacity will help prevent this from happening.

Don’t Forget About Grounding

If you pull the plug on your UPS to move it from the utility power supply to the generator, you’re also pulling the plug on the electrical grounding. A sudden loss of grounding on the UPS and all the equipment it powers could be a big problem: currents normally dissipated to ground through the UPS would find another path to get there, possibly through network cables, passing through other devices along the way.

Your in-house facilities manager or a local electrician should be consulted to make sure you have no safety or liability concerns. Your installation needs to maintain grounding, adhere to codes and minimize the chance of equipment damage, data loss and shock hazards.

Get Help Choosing the Right UPS to Work with Your Generator

Still unsure about which UPS system to buy? Tripp Lite’s Interactive On-Line UPS Product Finder will guide you through the choices to help you select the right on-line system for use with your generator.