What is UPS (Uninterruptible Power supply) ?
An electrical device providing an interface
between the mains power supply and load The UPS supplies sinusoidal AC power
free of disturbances and within strict amplitude and frequency tolerances.
It is generally made up of a rectifier/charger and an inverter together with
a battery for backup power in the event of a mains failure.
What are the UPS topologies?
All three major
topologies perform a basic level of power protection for computers and other
sensitive electronics. Users who do not require the highest possible power
availability to the critical load have options such as off-line or
line-interactive UPS devices.
The off-line UPS is so
named because the battery and/or the inverter are not supplying power to the
load except when the utility "fails." The failure of the utility requires
the switch to transfer to inverter. The inverter then starts and runs the
load. The total transfer time after the command to switch is usually well
less than a half cycle or eight milliseconds @ 60Hz and 10 milliseconds @50
Hz. The required decision and transfer time are usually acceptable for most
electrical loads. Off-line, (also called stand-by), is a cost-effective
choice for small, non-critical stand-alone applications, for example,
isolated PCs and peripherals.
line-interactive UPS utilizes the bi-directional inverter to perform two
functions, namely to run the load and to charge the battery. As the name
implies, the inverter "interacts" with the utility to maintain nominal
output voltage to the load. An ability to interact with the utility supply
improves the overall UPS performance over that of the off-line products.
Line-interactive UPS devices offer protection against wide input voltage
swings, sustained brownout and single-phase conditions. For many users, the
line-interactive UPS represents a very good level of protection for a
moderate investment. However, buyers should be aware that present
line-interactive technology does not perform at the level of an on-line UPS.
True on-line UPS
features an inverter that is on-line all the time, as well as a battery that
is always in the energy power circuit and not separated from the inverter by
switching means. The smooth, solid and repeatable performance of this
topology yields a number of tangible benefits, particularly worthwhile for
mission-critical applications. These include:
- Superior battery life.
- Superior line/load isolation, resulting in more
stable output voltage.
- Superior reliability with simpler controls and
no switching required for battery operation.
- Wide input voltage range which optimizes
battery life and potentially reduces battery costs by up to 75%.
- Assured reliable
performance of the critical load by properly maintaining the required
output voltage and providing more stable controls.
topologies -- off-line, line-interactive, on-line and hybrids -- work. The
question is whether a given topology is appropriate for a given application.
A true on-line UPS is most appropriate for truly mission-critical loads, or
applications which require high availability. If on-line UPS performance is
a requirement for the levels of availability expected of the
computer/technology investment, then the UPS must be "on-line" in the
traditional sense. When high reliability of electric service is required,
switching between alternate energy sources is not acceptable.
What is Backup time?
Time during which the
UPS can supply the rated load with nominal-quality power while the mains are
down. This time depends on the battery and the efficiency of the UPS.
Typical backup ranges from five minutes to several hours.
Harmonics (current and voltage)?
All alternating current
which is not absolutely sinusoidal is made up of a fundamental and a certain
number of current harmonics which are the cause of its deformation
(distortion) when compared to the theoretical sine-wave.
MTBF (Mean Time Between Failures)
Calculation of the duration of normal operation
of a repairable device between failures. The product, expressed in hours, is
an indication on the reliability of the device.
What is MTTF (Mean Time To Failure)?
Calculation of the
duration of normal operation of a non-reparable device, i.e. for which a
MTBF is not possible. The product, expressed in hours, is an indication on
the reliability of the device.
What is MTTR
(Mean Time To Repair)?
Calculation of the time
required to repair a device.
The Eco-Mode function allows cost-effective
operation of UPS Systems. In this operation mode, load is supplied by the
mains. In the event of a mains failure, the inverter takes over the load and
provides supply continuity to the connected systems.
What are the
advantages of IGBT rectifier UPS?
Thanks to DSP controlled
power factor corrected IGBT rectifier provides us higher input power factor,
lower input current total harmonic distortion, wide input voltage and
frequency tolerance. Inform UPS systems provide ≥0.99 input power factor
PFi, and ≤ 5% input current total harmonic distortion THDi.
High power factor helps you to consume less
reactive power and pay lower electrical pay out. It provides minimizations
of cable cross-sections, associated switchgear, transformer and generator
Low input current THDi
avoids disturbance to other loads connected upstream the power distribution
bus and interference reflected to the mains.
What are the advantages of Intelligent Battery
Considering the importance of the battery in a
UPS system, Inform uses special technology to maximize the battery lifetime.
It provides - charging voltage control according to temperature - protection
against deep discharge - protection against over current - very low
residual, ripple voltage - battery test with indication of battery