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____________________________________________________________________________________
Editorial Topic: Towards The most Efficient UPS: Eaton's Energy Saver
System
In October News we have presented Chloride new Trinergy UPS system designed for data centers
with a claimed maximum efficiency of up to 99 percent. Same month Eaton presented its Energy Saver
System option for Eaton 9395 and 9390 systems, which enable large, three-phase Uninterruptible power
systems (UPSs) to operate at 99 percent without sacrificing reliability.
Both Chloride and Eaton harness Eco-Mode principle to increase efficiency, suggesting new solutions to
overcome Eco Mode drawbacks.
Chloride's Trinergy uses the UPS inverter as an active filter to provide conditioned power. Whereas
Eaton's Energy Saver suggests a fast Turn - On Inverter, providing conditioned power through the
double conversion route.
According to Eaton, normal Eco Mode operation is associated with a hot standby inverter, which
consumes about 2% to 3% of rated UPS power. Energy Saver technology eliminates these losses,
achieving 99% UPS efficiency, by turning the Inverter off, during the Eco Mode regime.
Eaton's Energy Saver System
Eaton's Energy Saver system offers the following operational regimes, with automatic selection to
optimize power conditioning for achieving both protection and low losses:
Normal Mode: when utility is within acceptable limits, the UPS operates on bypass, providing 99% UPS
Efficiency and surge protection. The Inverter is turned off to save losses, while being in "Charged" and
synchronized condition.
High Alert Mode: UPS turns on its Inverter upon sensing a short term voltage or frequency deviation
problem and converts within 2 milliseconds to Double Conversion Mode for predefined period, before
returning to Normal Mode.
Storm Detection Mode: Sensing significant number of power disturbances during a short time, UPS
automatically switches to Double Conversion Mode for eight hours, before returning to Normal Mode.
Double Conversion Mode: Can be selected by user providing On Line Protection and 94% efficiency.
The technology is offered for new 400V and 480V, 9390 and 9395 UPS systems. Existing systems can
be field upgraded by Eaton's service. More information is presented on Eaton's Website.
Discussion:
July Newsletter, devoted to Eco Mode, indicates that this mode provides efficiency of 97% to 98%
versus 94% to 96% in Double Conversion regime.
Eco Mode like any other Standby operation, powers the critical load from utility, transferring to
Inverter's output whenever mains voltage deviates from preset levels.
Standby UPS systems are generally used for low power low cost and less critical applications, where
the UPS serves mainly as short time battery backup, to enable power outage ride through or graceful
shut down if outage persists. Standby disadvantages stem from unconditioned output during normal
operation, inability to correct Mains or external Generator's frequency deviations, uncorrected input
Power Factor and limited autonomy time.
An Online UPS with Eco Mode mitigates said drawbacks effect. The ability to transfer to Double
Conversion Mode provides conditioned power in unstable grid environments, solving also frequency
deviations as well as extended power outages by additional battery backup or backup generator.
Still, we are of the opinion that users are reluctant in implementing the Eco Mode. Despite the fact that it
is offered by some producers for quite a few years, and although it can be easy implemented by
modification of UPS software, it is still not accepted as mainstream by most UPS manufacturers. For
example more than 70% of Online RackMount UPS systems presented on UPSonNet's website do not
offer the Eco Mode feature.
Parting from the conservatively safe Double Conversion harbor raises doubts about Off Line solutions.
Concern with working continuously in an unconditioned environment, uncertainty about the health and
ability of the standby inverter to work with full load, worry about the ability to transfer smoothly at
mains outage, and "low cost technology" preconception associated with standby operation, may
disarm even an economically minded IT manager or consultant from voting for Eco Mode.
Chloride's architecture, offering continuously conditioned voltage, supported by working UPS inverter
seems to overcome better most mentioned drawbacks.
Eaton's Saver Technology may not be accepted by certain users. Conditioned power is not provided in
Normal operation. Transfer failure probability during mains outage still exists, although the High Alert
and Storm detection modes decrease significantly the probability of frequent transitions from Eco to
Online operation. Additionally, turning Off the Inverter increases Efficiency, but may cause concern
with regards to the health of the Dormant Inverter, and its ability to perform when called to action in
case of Power Emergency.
The said opinion refers only to technological aspects. Practical systems applicability is dependant on
numerous factors, such as specific product's design and features, field experience, cost per
performance considerations, as well as vindication of manufacturer's claims.
UPSonNet News
We have added in November to Industry Prices of UPS Systems categories, also the Industry prices of
Single Phase Online Rack Mount 120V UPS category. The price of these systems is higher compared to
Tower type units.
RM price presentation complements our Rack Mount Product Selector, enabling users to consider not
only UPS size, make and type, but also the price, before selecting the proper system. Our Press Release
titled New Uninterruptible Power Supply Prices Offer Generous Rewards to Savvy Buyers , advices
how considerable cost savings can be gained by consulting Industry prices.
Industry News
November News reveal UPS market trends, indicating that the industry, although mature, doesn't stand
still. See, Riello UPS Support services, Chloride's entrance to generator market, Borri UK leasing
service, and the tremendous Growth of Pentadyne a rotary UPS manufacturer.
We think that Facebook's recent decision, to follow Google and install batteries in the server cabinet
desires special consideration Such move might have a considerable impact on the UPS industry if
followed by more companies. More about it please read our April Newsletter topic titled: Learning from
Google's Server UPS Design.
_______________________________________________________________________________
Q&A referred to October Newsletter concerned with Trinergy UPS :
Some readers raised questions with regards to Trinergy UPS. Here we present the questions and
Chloride's replies, which Miss Letizia Ghirardello, Product Marketing Manager, Chloride Systems,
kindly provides:
Q: What is the change in UPS MTBF (Mean Time Between Failures) using each of the three
Modes:
Chloride Trinergy UPS, dynamically chooses the best functioning mode according with the mains
quality and load requirements guaranteeing the level of power conditioning required by the load and
achieving at the same time the highest possible efficiency. Only the components required to provide
secure power will be used by working in 3 different modes thus using all the power converters in more
distributes way (power interface Inverter, rectifier).
In addition Trinergy is able also to optimize the number of power modules necessary to supply power to
load. Thanks to the circular redundancy in case of output low load Trinergy will put some of the
modules in a special standby mode guaranteeing outstanding efficiency down to 20% of the load. The
same ageing of component is granted by rotating the module supplying load.
So it's clear that Trinergy can optimize the usage of all the components for the time that is really
necessary achieving outstanding Energy Saving and longer lifetime.
Q: How fast can the UPS transfer from the power conditioning mode (Inverter Acting as Active
Filter) to the double conversion mode?
Every Transfer to the different running mode can be defined as Zero transfer time.
Q: What is the delay time upon mains failure from power conditioning mode to the double
conversion mode?
There is no break.
Q: What are the output voltage deviations during load transfer from power conditioning mode
to the double conversion mode?
For Every transfer the Voltage deviation of the output complies with IEC/EN 62040-3, class 1.
Q: Can the voltage deviation during the said transitions cause dropping of certain loads?
No, thanks to excellent dynamic performances, due to Digital vector control of the Inverter output,
Patented vector control & Trinergy algorithm and improved hardware components. All this features
permit to have stable output performances independent from input conditions.
Q: Is back feed protection provided from UPS output to input terminals in case the AC input
breaker is disconnected?
Trinergy complies with safety standards IEC/EN 62040-1 so it provides the contact/s to command
external protection devices.
Additionally it will be possible to require a Trinergy system with internal backfeed protection device to
have plug and play safety solution.
Q: Can technical references (data sheets, average time in each regime, or other?) be provided,
supporting the statement in Chlorides Press Release that "average working efficiency in a
typical data center environment is 97.9%?"
Chloride has carried out an analysis of network data measured by its remote diagnostic and monitoring
system LIFE.net, a bi-directional, 24 –hour year round communication system designed to remotely
diagnose, monitor and manage the operational status of UPS and Power distribution systems through its
worldwide network.
The data relating to the functioning of UPS in real network conditions correspond with a sample of
2374 UPS monitored 24 hours a day, 365 days a year. A 12 month LIFE.net analysis carried out in 2008
proved that, on average Chloride UPS protected organizations against:
2709 out of tolerance per UPS
Out of tolerance average duration of 8 sec.
11 mains failures per UPS
120 Sec, average duration mains failure.
Applying the Trinergy algorithm to this real network conditions and considering a common Data centre
load, Trinergy in one year can work with average working efficiency of 98%.
Reader's Remark to October Newsletter Editorial Topic:
Mr Shri Karve, Director of Business Development, APC by Schneider Electric, remarks on the second
sentence of our comment which says: "It is unclear why UPS efficiency is reduced practically by four
percent if Eco Mode is selected.
Future loads, particularly those used in data centers are required today to provide almost unity power
factor eliminating the losses associated with upstream harmonics. "
Mr. Karve Says: " Even if the load power factor faced by UPSs is close to unity or even leading, one
would still face some percentage of harmonics from the load. Typical level of harmonics has come
down when compared with traditional servers but I have measured THDI levels of around 20 to 23 %
from new Blade Servers.
In view of the above one should not ignore harmonics and their changing profiles even if the THDI
levels have come down. Further more we should not confuse ourselves when comparing the two power
factors i.e. Displacement PF and True PF."
Our calculations confirm the correctness of Mr. Karve's remark, showing that PF of 0.95, as required
by Energy Star server spec, without displacement, has about 33 % current harmonics. Therefore the
phrase "eliminating the losses" in our Newsletter should be replaced by "reducing the losses".
Still, assuming a high upstream resistance of up to 5% of nominal load, and 0.95 input UPS Power
Factor, total UPS losses increase from 5% to 5.55 %, leaving the question in the first sentence of our
comment unanswered.
We welcome comments on the main topic, as well as to the questions/answers and remarks. Please
e-mail to: denis@upsonnet.com. Items of general interest will be presented in our next Newsletters.
______________________________________________________________________________
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| UPSonNet NewsLetter November 2009 |