UPS Full Form – Uninterruptible Power Supply

UPS Full Form

UPS Full Form – Uninterruptible Power Supply

The word “U.P.S.” is stand for “Uninterruptible Power Supply” or “uninterruptible power source” or “U.P.S.” is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails.

The world’s largest “U.P.S.”, the 46-megawatt Battery Energy Storage System (BESS), in Fairbanks, Alaska, powers the entire city and nearby rural communities during outages.

This has become popular even in the cheapest “U.P.S.” because it takes advantage of components already included.

A “U.P.S.” differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries, supercapacitors, or flywheels.

The “U.P.S.” on-battery run-time of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment.

It is a type of continual power system.

A “U.P.S.” is typically used to protect hardware such as
data centers,
telecommunication equipment or
other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss.

UPS Full Form – Uninterruptible Power Supply

“U.P.S.” units range in size from units designed to protect a single computer without a video monitor (around 200 volt-ampere rating) to large units powering entire data centers or buildings.

Common power problems   Edit
The primary role of any "U.P.S." is to provide short-term power when the input power source fails. 

However, most “U.P.S.” units are also capable in varying degrees of correcting common utility power problems:

Voltage spike or sustained overvoltage

Momentary or sustained reduction in input voltage

Voltage sag Noise, defined as a high frequency transient or oscillation, usually injected into the line by nearby equipment
Instability of the mains frequency

Harmonic distortion, defined as a departure from the ideal sinusoidal waveform expected on the line

UPS Full Form – Uninterruptible Power Supply

Some manufacturers of “U.P.S.” units categorize their products in accordance with the number of power-related problems they address.


The three general categories of modern “U.P.S.” systems are on-line, line-interactive and standby:

An on-line “U.P.S.” uses a “double conversion” method of accepting AC input, rectifying to DC for passing through the rechargeable battery (or battery strings), then inverting back to 120 V/230 V AC for powering the protected equipment.

A line-interactive “U.P.S.” maintains the inverter in line and redirects the battery’s DC current path from the normal charging mode to supplying current when power is lost.
In a standby (“off-line”) system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails.

Most UPS below one kilovolt-ampere (1 kVA)
are of the line-interactive or standby variety which are usually less expensive.

For large power units, dynamic uninterruptible power supplies (DUPS) are sometimes used.

A synchronous motor/alternator is connected on the mains via a choke. Energy is stored in a flywheel.

When the mains power fails, an eddy-current regulation maintains the power on the load as long as the flywheel’s energy is not exhausted.

UPS Full Form – Uninterruptible Power Supply

DUPS are sometimes combined or integrated with a diesel generator that is turned on after a brief delay, forming a diesel rotary uninterruptible power supply (DRUPS).

A fuel cell UPS was developed by the company Hydrogenics using hydrogen and a fuel cell as a power source, potentially providing long run times in a small space.

The offline/standby “U.P.S.” offers only the most basic features, providing surge protection and battery backup.

The protected equipment is normally connected directly to incoming utility power. When the incoming voltage falls below or rises above a predetermined level the “U.P.S.” turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery.

The switch-over time can be as long as 25 milliseconds depending on the amount of time it takes the standby UPS to detect the lost utility voltage.

The “U.P.S.” then mechanically switches the connected equipment on to its DC-AC inverter output.

The “U.P.S.” will be designed to power certain equipment, such as a personal computer, without any objectionable dip or brownout to that device.

The line-interactive “U.P.S.” is similar in operation to a standby “U.P.S.”, but with the addition of a multi-tap variable-voltage autotransformer.

This may also be performed by a buck–boost transformer which is distinct from an autotransformer, since the former may be wired to provide galvanic isolation.

UPS Full Form – Uninterruptible Power Supply

This is a special type of transformer that can add or subtract powered coils of wire, thereby increasing or decreasing the magnetic field and the output voltage of the transformer.

Depending on the design, changing the autotransformer tap can cause a very brief output power disruption,which may cause UPSs equipped with a power-loss alarm to “chirp” for a moment.

It instead compensates by automatically selecting different power taps on the autotransformer.

This type of “U.P.S.” is able to tolerate continuous undervoltage brownouts and overvoltage surges without consuming the limited reserve battery power.

The main 50/60 Hz transformer used to convert between line voltage and battery voltage needs to provide two slightly different turns ratios:

The One to convert the battery output voltage like “a multiple of 12 V” to line voltage, and a second one to convert the line voltage to a slightly higher battery charging voltage such as a “multiple of 14 V”.

It is easier to do the switching on the line-voltage side of the transformer because of the lower currents on that side.

The difference between the two voltages is because charging a battery requires a delta voltage (up to 13–14 V for charging a 12 V battery).

UPS Full Form – Uninterruptible Power Supply

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