UPS Vs Inverter

They are same when used in the context of backup supply.

But inverter per se is a different animal, and is a part of many devices for example Variable speed drives.

A UPS contains a battery and charger, and an inverter specifically designed to convert the battery output to the required local mains voltage & frequency.

An online UPS continuously charges the battery and drives the inverter with DC - which then provides the mains output.

An offline UPS continuously charges the battery, but bypasses the inverter to provide the mains output while the mains input is OK. It automatically detects when the mains input goes out of spec, and switches over to the inverter.

Dear Friend

Inverter converts DC input to AC output.

UPS - UNINTERRUPTED POWER SUPPLY, provides UNINTERUPTTED power supply ( read AC in common terminology ). Thus to provide CONTINUOUS & UNINTERUPTTED AC supply during AC mains failure, battery is provided as a source of power. The inverter SECTION of the UPS converts this DC input to required AC supply. Control circuit ensures that AC supply is ALWAYS ( read UNINTERUPTTEDLY ) available on the AC output side. To keep the battery in charged condition so that it can deliver required DC power during Mains AC supply failure, a battery charger is also provided.

Thus EFFECTIVELY INVERTER is one of the section of UPS.

Thanks and regards

Ashok Toshniwal, Bangalore, India

Inverter is made to invert or "change" the power; for exemple from 230V Ac to 24V dc, or 12Vdc to 230V ac, or any other changes. Ups is on the other hand a standby power, usually includes 12V or 24v battery pack. For exemple one UPS can be conected to 230V socket and charge 12V battery and to the Ups you can connect your computer. In the case of powerfail to the ups, the ups will convert the 12v dc power to 230v ac feeding power for your computer = the computer will not shut down.

GJA

"Inverter is made to invert or "change" the power; for exemple from 230V Ac to 24V dc, ..."

Nope, sorry, you are just wrong about that.

Inverter is used only to describe a system that changes DC to pseudo AC. Changing AC to DC is a different task and that device is called a "Converter" or "Rectifier".

Both an inverter and an UPS convert DC to AC... And they do perform the same function. However the difference exist in the fact that an UPS is an inverter and is designed to be used for a particular function, but an inverter cannot be generalized into an UPS. The difference may also exist in the following

1) Time of response i.e. an UPS has to be able to detect current outages faster but an inverter need not neccessarily need to respond that fast. Certain delay may be allowed.

2) Backup time: UPS's predominantly dont give much backup i.e. not more than 15-30 minutes but inverters are designed on a much larger scale and power a variety of devices. Thay are also more rugged...

Yes that is right, inverter is dc to ac, but you can also get one unit that combines dc to ac inverter and a charger for batteries, and in that case you can feed the unit with 230V and charge 12v or 24V battery packs. Combined unit like this is used for exemple in a boat with 24v batteries. When sailing, the inverter changes the power from 24dc alternator to 230V ac. And when the boat is at shore, the same unit is connected to 230V ac socket and charges the 24v batteries.

GJA

For a laymen question I shall give you lay men answer.

UPS means Uninterrupted power supply . Say when your computer is connected through a UPS Even when the power fails the computer will go on working as if nothing happened.It will comprise of AC to DC conversion , Battery Back up and inverter from DC to AC and it will be all the time in circuit. No change over switch is required

How long it will continue to work after the power failure will depend on its AH capacity. It's capacity is defined in terms of VA( Volt- Ampere)how much load it can take and AH( Ampere Hour) How long it can work with certain load.

Inverter as the name means is the reverse of converter.Converter converts AC to DC and Inverter converts DC to AC a reverse process. An inverter commercially is marketed as stand by power system which can be switched on manually or automatically when the power fails.It comprises of Battery charging system and DC to AC converter. In this case also capacity is defined in terms of VA and AH .

It's worth pointing out that the term UPS does not automatically infer having a battery backup and an inverter. UPS can also be applied to rotary power back-up systems such as flywheel storage and engine-generator systems with flywheel carryover. All that UPS means is "Uninterruptable power Supply".

In addition, besides UPS and VFD applications, there are also just plain Power Source inverters not used as UPS systems, such as you would find in the devices that provide AC power on boats and vehicles. Inverters are also a component of many aircraft Ground Support Equipment (GSE) power supplies and most energy efficient lighting ballasts now as well.

So to sum up;

You can have an Inverter Drive, you can have an inverter power supply, you can have an inverter UPS, you can have an inverter ballast.

You can have an inverter UPS, you can have a rotary flywheel UPS, you can have an engine UPS, with or without a flywheel or inverter carryover.

A simple system for a Battery UPS may look something like this:-

Andy in Germany has it just right because his diagram shows the best reason to have a UPS in line.

Here in the South of the U.S. it is not uncommon to have many power outages due to the fact that the power conglomerate makes money every time their above ground transmission facilities are damaged by storm, vehicle, or otherwise. With outages, as well as for other reasons glitches, high voltage momentary pulses, are not unusual. Computers can be sensitive to such.

It therefore is of benefit to have a UPS in line insofar as the battery, inductances, and capacitors of which it is made up, provide a very good filter against aforesaid glitches.

j.

You points are well made and I forgot them completely in mine, thanks for the additions.

Regards !

I have to add:

Inverter

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Converts normally from DC to AC.

Examples:

1. Drives:

Fixed-Voltage-Fixed-Frequency or Variable-Voltage-Variable-Frequency.

This type of Inverters are from-AC-to-AC Inverters; surely AC is converted to DC first

& again DC is converted to AC of required Frequency & Voltage.

Rectifier portion is normally termed as "Converter"

House-Hold Inverter:

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This is normally runs on Battery (s) and run on outage of Utillity Power.

It surely inclueds "Battery-Charger"

This Inverter needs a Battery; built-in or External.

Uninterruptible-Power-Supply (UPS)

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As its name says critical load running on UPS is NOT INTRUPTED on BLACK-OUT/GREY_OUT of

Utillity Power.

It includes Converter [Rectifier], Battery [Stand-by-Power-Source]; Inverter & Cotrol-Electronics +

Swith-Gear etc etc depending on the size & type of UPS System

Two types are in use [Small Units only]

1. On-Line: Critical-Load remains continuously on UPS output. No break in power.

2. Switched: Critical-Load remains on Utillity Power & Inverter remains in Stand-by.

On outage of power Inverter starts & Critical-Load switched to UPS output. Some break in power to load

is expected. Normally less than a 1/2 cycle in well designed ones.

In Medium Power & Large UPS Systems load remains on UPS & transferred to Generators in long outage of power.