Eco-Friendly Choice in Single Phase UPS
By Miguel Rascon
AC Power Senior Product Manager
Abstract
“Environmental protection”, “high efficiency” and “energy savings” are nowadays trendy topics and as they also
apply to UPS, UPS have become a trendy topic as well. ECO mode represents an interesting feature in UPS technology
in particular related to small or single-phase applications with less than 10 kVA. UPS industry has spread its use in the
last few years for applications using on-line double conversion products. These products, characterized by double
power conversion stages, usually lacked high efficiency performance during on line operation mode, which is why
the use of ECO mode brought an extra value to achieve higher efficiency and energy savings. However there is a
former ECO mode used inherently in other UPS products and perhaps no so well known: this is exactly the topic we
are going to deal with in this paper.
Eco-Friendly choice in single phase UPS
“Environmental protection”, “high efficiency” and
“energy savings” are topics of very high concern for
both large corporations, as well as for individuals since
these aspects are part of everyday life and may generate
significant cost savings in both cases.
This is also valid for UPS ranging from large ones
protecting substantially vast datacenters, to small ones
with just a few kilowatts that safeguard a network or
single cabinet in more modest settings.
The ECO mode (also known as “energy saving mode”
or “high efficiency mode” depending on the UPS
manufacturer) is currently highly discussed within the
industry. The debate primarily focuses on on-line UPS
and on large UPS. Nevertheless, energy savings and
efficiency are extremely important aspects also in small
and micro power UPS (typically from 500 VA to 10 kVA).
The reasons are the same as for large power systems:
savings on energy costs and lower environmental
footprint.
Choosing a UPS in the most proper way, means
considering the criticality of the application that needs
to be protected, as well as evaluating the energy used
by the UPS to protect the load against disturbances and
interruptions.
In this paper, I would like to highlight the “inherent ECO
mode” that can be found in line interactive UPS products
(VI or “voltage independent” according to EN62040-3).
In this type of line interactive UPS (VI), the power stream
flows from the input through several protection devices
(overcurrent, overvoltage, etc.) and mainly through an
Automatic Voltage Regulation (AVR) transformer.
2
The AVR is in charge of providing output voltage
regulation, in order to minimize voltage variations in AC
supply and ensure a regulated voltage according to the
load tolerances.
Because of the high efficiency of the AVR (typically
around 98% or 99%) and of the protection devices
through which energy flows, as well as the lower quantity
of electronic components used in this type of UPS
topology, a high performance line interactive UPS can
provide an efficiency level higher than 96% at full load. A
perfect example of this is Liebert PSI UPS, which makes
use of line interactive technology and therefore of AVR,
and which can reach the efficiency levels mentioned
above. As said, this operation mode is inherent to line
interactive UPS topology, and its high efficiency is also
ensured in wide load operating conditions and AC mains
variation. While ECO mode in on-line UPS is operating in
a smaller input voltage range, line interactive topology
is able to operate in high efficiency mode during most
input voltage changes while still being capable to
provide some output regulation.
When comparing a line interactive UPS with a double
conversion online UPS there are many aspects to be
taken into consideration such as stepwise or pure sine
wave inverter, transfer time, size, etc. However one of
the main differences is exactly that line interactive UPS
feature “inherent high efficiency” because of the VI
technology and the use of AVR as mentioned earlier.
The energy savings associated to it are highly appreciated
even if we are talking about single phase UPS meaning
UPS which range from 0 to 10 kVA, because:
1.Daily saving just a few watts in continuous UPS
operation 365 days a year amounts to a significant
total yearly saving
2.In applications such as campuses or big corporations
where many of these small UPS devices are used
contemporarily, the few watts saved daily per each
device increase even more the daily and yearly total
saving and reduce the total campus or corporation
expenditure.
To provide an example, assume a load of 2.5 kW being
protected by a UPS. Such load may correspond to a
cabinet with several servers for enterprise applications or
to a wiring closet distribution panel. Such UPS can work
in line interactive mode (assuming 97% efficiency) or
operate in double conversion mode with 90% efficiency,
using a rough estimation. The difference in power losses
and thus energy savings, will be around 200 W. Assuming
an electricity cost of 0.138 €/KWh and doing a quick
calculation on yearly savings, you can get a value of around
272 € saved per year. This amount can be multiplied for
five years and the total saving will reach nearly 1,500 €.
So it will be clear by now that additional to traditional
ECO mode (typically used in double conversion online
UPS in general and large UPS in particular) there is an
inherent ECO mode used in single phase UPS, specifically
line interactive ones.
This grants significant savings to customers as the line
interactive technology is inherently highly efficient and
as the UPS making use of it are typically used daily all
year long so in the long term even little daily saving
amounts to a considerable total figure.
And what about ECO modes in on-line UPS in this small
UPS range? Is there any difference or advantage? There
is an interesting story too, but this will be dealt with in
another paper.
3
Ensuring The High Availability
Of Mission-Critical Data And Applications.
About Emerson Network Power
Emerson Network Power, a business of Emerson (NYSE:EMR),
delivers software, hardware and services that maximize availability,
capacity and efficiency for data centers, healthcare and industrial
facilities. A trusted industry leader in smart infrastructure
technologies, Emerson Network Power provides innovative data center
infrastructure management solutions that bridge the gap between
IT and facility management and deliver efficiency and
uncompromised availability regardless of capacity demands.
Our solutions are supported globally by local Emerson Network Power
service technicians.
Learn more about Emerson Network Power products and services at
www.EmersonNetworkPower.eu
Locations
Emerson Network Power
Global Headquarters
1050 Dearborn Drive
P.O. Box 29186
Columbus, OH 43229, USA
Tel: +1 614 8880246
Emerson Network Power
Europe Middle East And Africa
Via Fornace, 30
40023 Castel Guelfo (BO) Italy
Tel: +39 0542 632 111
Fax: +39 0542 632 120
ACpower.Networkpower.Emea@Emerson.com
Emerson Network Power
United Kingdom
George Curl Way
Southampton
SO18 2RY, UK
Tel: +44 (0) 23 8061 0311
Fax: +44 (0) 23 8061 0852
While every precaution has been taken to ensure accuracy and completeness herein,
Emerson assumes no responsibility, and disclaims all liability, for damages resulting
from use of this information or for any errors or omissions.
Specifications subject to change without notice.
EmersonNetworkPower.eu
Globe Park
Fourth Avenue
Marlow Bucks
SL7 1YG
Tel: +44 1628 403200
Fax: +44 1628 403203
UK.Enquiries@Emerson.com
Follow us on Social Media:
Emerson. Consider it Solved, Emerson Network Power and the Emerson Network Power logo are trademarks and service marks of Emerson Electric Co. or one of its affiliated companies.
©2014 Emerson Electric Co. All rights reserved.