Modify computer inverter to accept power from house inverter

[gotchanisa]

I have a UPS at home - for the whole house. However, everytime there is a power outage, my computer restarts. It does not restart when the power comes back! I had an old computer UPS that I had that I connected to the computer. Now when the power goes, the computer does not restart - but the computer UPS does not 'recognize' the power coming from the main House UPS. So instead of a 5 hr back up - that the house UPS gives me, I only have the 15 min back up that the computer UPS can give me. I have talked to UPS manufacturers who say they need to fit a 'filter' which will solve the problem - but they were not able to make it. They said something about a pure sine wave output- not sure if I understood. Anyone have a cost effective solution that will make my computer inverter 'recognize' the power coming from my main inverter?

 

[CWatters]

It sounds like the house UPS is of the stand by type rather than a double conversion type. In the event of a power outage a stand by type switches on its inverter and switches the load from the mains to the inverter. This isn't seamless so the computer crashes. If it was a double conversion type the inverter would be running constantly so change over would be seamless but there would be constant power loss in the inverter making it more expensive to run.

It also sounds like the house inverter only generates a crude approximation to a sine wave and that is confusing the computer UPS into thinking the input is too noisy to use. The vendor is saying that an inverter that generates a pure sine wave might not confuse the computer UPS.

I'm not sure what to recommend. A pure sine wave UPS capable of powering the whole house might be too expensive.

One possibility might be to buy an inverter rated for just the computer and connect it to the big battery in the house UPS. This inverter would run all the time so no issue when the power goes out. The only problem I see is that you might/wont get any warning when the 5 hours are up. You would have to rely on any warning the house UPS gives you.