I have a some experience with UPS and battery systems. I work in an industrial corn plant, and we use UPS units to back up our critical DCS units, so that if the plant loses main electrical power, we can safely bring the plant down. We use Eaton Ferrups 18kVA units, rated for 120/240v. The different components are the Bypass Switch, UPS, and Batteries. The Bypass Switches we use have make-before-break switches. You can control where the power is flowing using the Bypass Switch.
Bypass Switch Positions
- Line - the switch in the line position means that the incoming power is bypassing the UPS unit entirely and going to the critical loads. This is useful when performing maintenance on the UPS or batteries. These switches are make-before-break, so there's no power "blip" when you turn these switches. When the switch is in this position the batteries are being charged. If you lose incoming power while the switch is in the Line position, the critical load will not receive power.
- UPS - the switch in the UPS position means that the incoming power is going through the UPS and being "conditioned" (i.e. getting rid of harmonics, better power quality). Keep in mind this doesn't mean that the batteries are powering the load at this point. The batteries only power the load when the incoming power feed is lost in this position. If the incoming power is online, not only will having the switch in this position clean up the incoming power, this will also charge the batteries.
- Off - the switch in the Off position means that incoming power is now disconnected, and the UPS will run off the batteries. I think this is mainly used to simulate main incoming power failure.
I think the above positions are generally used throughout the industry, although different manufacturers might call them different names. As far as the wiring goes, there should be a wiring diagram in the manual, I would look there to find the particular schematic for your unit. Hope this helps.
