Hi my fellow nerds,
I'm participating in the design of a nice particle physics detector. One interesting thing is that we have 2 types of power: Quiet power, low noise with controlled ground impedance for measuring equipment; Common power, for common and high power application. In the event of a power outage, only the common power is backed up using a generator.
Most systems have a UPS, but the critical ones have to have redundant power as well. That is, the UPS would have to be able to charge from the back-up generator power in the case we have long power outage.
The thing is, there is one system which requires redundant power and also quiet power. And this is a problem, because if we use a simple dual input UPS, we are crossing the ground connections in both circuits (quiet and common) which defeats the purpose... And it is not acceptable for the noise level we are trying to achieve.
The currently solutions is to have people babysitting the experiment. In the case of a power outage, the person would physically change the outlet the UPS is connected to. There got to be a better solution!
Do you know a UPS which is capable of fully switching between 2 circuits? Including grounds!
I guess another options would be to create a simple relay circuit, or even better would be a motorized switch like they have for solar+mains+backup. But the approval process for "homemade" gear is a pain...