UPS System

http://answers.yahoo.com/question/index?qid=20080213202604AAboHfD

online UPS = parcel arrives

offline UPS = parcel doesn't arrive

Off line or on line parcel arrives on dot time by UPS.So there is no difference ( Known by experience). Ofcourse joke.

On line UPS is always in circuit. Off line have to be pushed on when supply fails in simple terms

Another thing I would add to soebfatehi's link would be that the "online" UPS usually supplies power from a double-inverter integrated into the UPS. This allows frequency adjustments and negates variations from the incoming voltage and frequency considerably. Basically, your load is powered off of the float on the battery bank or flywheel, dependent on your UPS type.

On-Line UPS: The power flow is through the Battery Charger and Inverter under normal condition. The power flow switches to the bypass system if the UPS encounters a problem, such as failure or overloaded.

Off-Line (or Standby) UPS: The power flow is directly from the commercial source under normal condition. UPS is used only when the utility power fails.

- MS

is it possible to build a kinda prospective ups wherein the impending loss of power is sensed and battery power is supplied in anticipation thus reducing the duration of lost power?

if this is not already being done then it can become the next big thing after Noah's ark . . . .

When using the inverted output of the UPS there is no loss of power whatsoever at the output during interruptions or sags.

The system is already been built and are running in place. Static Transfer Switch (STS) does the job of transferring from a failure (or faulty) source to another standby source (from UPS to Bypass for Online UPS and Bypass to UPS for Offline UPS system). STS monitors the condition of both sources and it transfers the load from failure (or faulty) source to the healthy source within few milliseconds (almost zero-break time) and thus the load doesn't experience the power loss during the transfer.

See this link for more about STS:

http://www.frost.com/prod/servlet/market-insight-top.pag?docid=7225997

- MS

Alternately a static transfer switch can be used between two or more UPS', the UPS' and the mains, the UPS' and a generator bus, etc.

We have two UPS' running through a static transfer switch tied to a shared bus. The UPS' also have a static switch built into them to allow for a maintenance bypass. There are also maintenance bypasses installed upstream of the UPS' to allow for maintenance of the entire path.

There is such a plethora of configurations which allow maintenance of switchgear and equipment which never causes an interruption to the load.