Uninterruptedly Power Supply (UPS) information

[klaukholm]

There seems to be a need for general information on UPS technology. Please post personal experiences and some dos and don'ts. It would be valuable to hear from members who have solutions that have saved them in a pinch as well as solutions that have failed.

Here is some general information I was given from an engineer who designs UPSs.

Almost all UPSs have a bypass system to supply power when the UPS fails. It is not foolproof but it helps. If the system requires more reliability, then 2 or more UPSs are paralleled so that if one fails the other will continue to supply power. Chloride has bypasses or “static” bypasses in all their UPSs. Static meaning that it has no moving parts (i.e. electronic). The others have relays or contractors.

This all depends on the power level you are interested in. Chloride makes or distributes UPSs from 200 VA to 750 KVA. We can parallel from 6 KVA and up.

There are two major categories of UPSs.

1. Standby or line interactive: This is where the line power is used until a power outage occurs and then the inverter is started and supplies power. The major failure occur when transferring from line to inverter.

2. Double conversion: This is where the inverter runs all the time. The rectifier supplies power to the inverter and also charges the battery. When power goes out, the rectifier stops and the inverter is supplied from the battery with no break or transfer More reliable but a higher cost.

UPSs last up to ten or more years depending on the maintenance agreement or schedule. The batteries will typically last 3 to 5 years. Some longer, up to twenty years, depending on the type you buy.