The primary task of a UPS system is to protect the
load from down time caused by potential power problems. A UPS must be
able to cope with all the power problems which exist in the utility
However, when choosing any type of electrical
equipment it is important that operational costs are taken into
account. Operational costs consist of electrical, operations staff and
maintenance costs. In UPSs the electrical costs are closely linked to
the efficiency of the UPS equipment.
The efficiency of a UPS system needs to be measured
in an actual installed environment. The type of load, stability of the
utility power and the effect of partial loads are all factors which
need to be taken into account.
There are many competing claims about the relative
efficiencies of different types of UPS topologies. When tested in
laboratory conditions the efficiency ratings for various types of UPS
can be misleading. The reason for this is that the parameters of
utility power input and the load can be precisely controlled and
optimized to produce the highest efficiency levels. When the UPS is
used in real life situations the results can be radically different.
In a normal operating environment the most
important elements, as far as factors for efficiency, are: input
voltage fluctuations, load level of the UPS and the type of load.
Voltage fluctuations are present in just about all
utility systems. Most UPS are able to correct them, but some designs,
for example line-interactive UPSs, have low efficiency when they are
forced to regulate voltage.
Partial loads are very common as UPSs are hardly
ever 100% loaded in real-life situations. In most installations some
allowance for load expansion is made. Single UPS units are typically
60-80% loaded. When two or more units are run in parallel
(redundancy), it automatically means that the UPSs are not fully
loaded under normal conditions. For example when a 200kVA load is fed
through two 250kVA units the load for each UPS is only 40% of the full
capacity. It is important therefore to consider whether the UPS you
choose will offer high efficiency under low or partial load conditions
IT equipment, including computers, are typically
powered by what is called Switch Mode Power Supplies (SMPS). These
power supplies are small and cost-effective, but have a special
characteristic in that they draw electrical current from the mains in
bursts which gives a non-linear waveform. Therefore, when protecting
computers, the efficiency of a UPS needs to be determined under
computer (non-linear) load conditions.
A double conversion on-line UPS regenerates power
continuously regardless of the input voltage and load waveform.
Therefore because the rectifier and inverter are used continuously any
change in the input voltage or load conditions has very little effect
on the operation and efficiency of the UPS. Double conversion not only
offers the highest level of protection available but also, through the
use of advanced IGBT and DSP electronic circuitry can offer the
highest levels of efficiency as well (up to 94%). Use of these
technologies means there are less components in the UPS, which in turn
means less energy is consumed.
Line interactive (including Delta Conversion) UPSs
compensate for the deficiencies of the utility power and distortions
caused by the load. This means that if the load and utility power are
set to optimal levels, the UPS does not need to compensate for any
deficiencies (in effect does not need to do anything) and therefore
high efficiency levels can be achieved under laboratory conditions. In
contrast when this type of UPS is used in real life situations there
are inevitably going to be voltage fluctuations which will cause the
output converter to be employed and typical computer loads will create
waveform distortion which means the input converter also needs to be
used. These converters consume power, which means the overall
efficiency of this type of UPS can in fact be much lower in a normal
operating environment compared to 'ideal' laboratory conditions. When
combined with the fact that these units do not operate very
efficiently under partial loads, it is apparent that the real life
efficiency is typically lower than in a modern double conversion UPS.
In conclusion, as the performance of a modern
double conversion UPS is not dependent on the utility or load
conditions it offers the highest efficiency in real world
installations. Not forgetting that it also offers best power
A globally recognized industry leader for more than
40 years, Powerware designs and manufactures a full line of
Uninterruptible Power Systems (UPS), DC power systems, power
management software/connectivity products. Powerware products are
typically used in networking, PC, financial, medical, industrial,
voice and data communications, military and aerospace applications -
wherever continuous power is essential to daily operations. Powerware
is headquartered in Raleigh, NC, and is part of Eaton Corporation.
The company offers a full range of UPSs ranging in
size from 300 volt-amperes (VA) for personal computers to greater than
1,000 kilovolt-amperes (kVA) for mission-critical applications
including data centers, Internet service providers, and server farms.
Network-connectivity devices, extended battery cabinets, power
distribution modules and other power-related devices further enhance
Powerware UPS hardware offerings. The Powerware product portfolio also
includes a full line of DC Power Systems ranging in size from mini
systems for roadside cabinets or customer premises equipment to large
systems for major switching installations. Power management software
and IT infrastructure management software complete the company's
product line. Basic power management software provides
industry-standard monitoring, alarm and shutdown capabilities. More
advanced software packages offer expansive data archiving, trending
and regression analysis tools with predictive capabilities. With
innovative software that can predict the type and timing of possible
future events, Powerware is leading an industry shift from reactive
power protection to proactive power management.
Eaton Corporation is a diversified industrial
manufacturer with 2003 sales of $8.1 billion. Eaton is a global leader
in fluid power systems and services for industrial, mobile and
aircraft equipment; electrical systems and components for power
quality, distribution and control; automotive engine air management
systems and powertrain controls for fuel economy; and intelligent
drivetrain systems for fuel economy and safety in trucks. Today, the
company classifies its business into four distinct segments, which
are, by size: Fluid Power, Electrical, Automotive and Truck. Eaton has
51,000 employees, 207 manufacturing sites and sells products to
customers in more than 100 countries.
GemNet is a power solutions company, providing
quality power products and services. Our philosophy has always been to
combine its local expertise and commitment with quality products,
technical competence and the support of its principal. Since
inception, it has been our goal to build deep and long lasting
relationships with our customers and alliance partners by providing
them top-quality power products and services. This has been the single
most important success factor for GemNet, earning it the reputation as
one of the leading and most professional power products and solutions
companies. Today, GemNet enjoys an established track record of
excellence with its customers in Pakistan and the United Arab
Emirates. GemNet is the authorized distributor for Eaton Powerware's
range of AC and DC Uninterruptible Power Systems, and offers a large
range of specialized power related products and services. The company
has local offices in Karachi, Lahore and Islamabad (GemNet Pvt.
Limited) and Dubai, United Arab Emirates (GemNet Gulf).
AREAS OF EXPERTISE:
* Service plans to fit the clients needs, including
plans that cover the client's existing Power Systems and UPSs.
* Services also include: Needs Analysis,
Comparative Product Analysis, Cost Justification, End-User Training,
Maintenance, After Sales Support, Data/telecom center, electrical
contracting and site preparation.
* Power Consulting & Critical Environment Site
Audit (CESA): Audit of existing UPS and recommendation of a power
solution. Analysis of the quality of power feeding the systems.
Facility/Site inspection, identification and correction of the