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8/7/2019 heat load upsNetworkCloset_Low052308

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A White Paper rom the Expertsin Business-Critical ContinuityTM

Power and Cooling Design Guidelines forNetwork Access Rooms


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Introduction

Network access and telecom rooms arehousing more powerul and criticalequipment as businesses rely on thesespaces to support an increasing number

o business-critical applications. Thetechnologies supporting the deploymento IP telephony, wireless networking,converged applications, and otherequipment outside traditional IT data storageand management are nding their way intonontraditional spaces that werent designedas data centers. These rooms also supportimportant operational unctions includingtime and attendance equipment, buildingmaintenance alarms and security equipment.In the event o a ailure within a networkaccess room, organizations may besusceptible to the disruption orevenue-generating activities or theinoperability o security and phone systems,among other serious consequences.

Because network access equipment hastraditionally been housed in convertedclosets or other spaces not well suitedor electronics, its reliability and that onewer devices has been placed in jeopardy.

These spaces oten constrain growth orenhanced use o the closet because o thelack o physical space and power/coolinginrastructure required to support thepowerul and critical equipment on whichthe business is now dependent (Figure 1).

More powerul equipment generates moreheat. When the equipment is trapped ina small, poorly ventilated space, heat canquickly raise the temperature to unsaelevels that reduce perormance and shorten

equipment lie. Additionally, the hardwarerunning these applications requires higheravailability power protection through anuninterruptible power supply (UPS) system.

Threat to Business ContinuityFor example, Voice over Internet Protocol(VoIP) can change the economics associatedwith network access downtime by addingsignicant costs to a business should there bea disruption. When evaluating the criticality

o network and telecom closets, IT managersshould review applications supported bythe network and evaluate the impact tothe business i those applications becomeunexpectedly unavailable. Addressing costsassociated with employee productivity andrevenue-generating activities should not beoverlooked. As downtime costs rise, so tooshould the investment in technologies thatcan increase availability.

Conguring the appropriate solution involvesboth overcoming the physical challengesimposed by the space and understanding thecost o downtime or the environment. Thegood news is that there are solutions availabletoday that allow powerul and sensitivenetwork equipment to operate saely andreliably in almost any environment.

Figure 1. New switches, routers and otherequipment being deployed as part o an ITsystem upgrade may require enhanced powerand cooling support.

Evaluating the Physical Environment

The network access room environment posesa number o challenges or power, cooling

and monitoring systems. Evaluation o thenetwork closets size and existing powerand cooling attributes will help ensure thatit is designed with solutions that can easilysupport growth and fexibility as businessneeds change.

1

More powerul

equipment generates

more heat. When the

equipment is trapped

in a small, poorly

ventilated space, heatcan quickly raise the

temperature to unsae

levels that reduce

perormance and

shorten equipment lie


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SizeThe small size o network access roomscan limit power and cooling equipmentcongurations. Most network access roominstallations require UPS systems that willtake at least 2U o rack space, not including

extended runtime batteries.

Existing CoolingCooling and ventilation will determine howeectively heat can be removed rom the rackand rom the access room. Equipment typeand access room size will largely determinecooling requirements. Simple ventilationmay suce, or a dedicated cooling systemmay be warranted. Initial considerationsshould include ventilation o the access room,

ducting o walls and ceilings, and year-roundavailability o building air conditioning.

Existing PowerWhen evaluating a room to handle networkequipment, check out elements o therooms existing power supply to see i it canadequately support the technologies that itmay house.

The size and number o circuits requiredare determined by power usage and

redundancy requirements. Support or Powerover Ethernet (PoE) can quadruple powerrequirements. Certain redundancy strategies,such as dual bus may require more than onecircuit or UPS systems. I additional circuitsmust be added, it is wise to provide someroom or uture growth as new PoEstandards will allow the ormat to supporthigher-powered devices such as laptops.

Also, the type o wall receptacles in theaccess room will impact compatibility withUPS systems. For example, UPS systemswith capacities o more than 2,000 VAhave dierent plug types that may not tthe commonly used 15 amp or 20 ampreceptacles in network access rooms.

These actors, along with building layoutand network equipment criticality, will drivethe decision on whether to use centralizedor decentralized UPS systems. Someorganizations may be able to utilize a single

UPS located in a computer room to protectnetwork access rooms throughout the samebuilding. The advantages o a centralized UPSwith larger, more robust technology includelower cost o ownership and higher systemavailability because o ewer potential pointso ailure and easier management (Figure2). This approach also simplies service andmaintenance requirements.

Others may adopt a decentralized strategyin which UPS systems are located in eachrack or access room. Advantages o thisstrategy include simpler installation and loweinitial cost. Highly reliable, rack-mounted,line-interactive and double-conversion UPSsystems are available rom 700 VA to 10kVA, making it practical to deploy powerprotection in almost any environment housinrack-mount servers, switches and routers.Also, new 208V UPS systems increase the

2

Module Capacity Size

CostperCapacityUnit

Smaller UPS modules

Larger UPS modules

The advantages o

a centralized UPS

with larger, more

robust technology

include lower cost

o ownership andhigher system

availability because

o ewer potential

points o ailure and

easier management.

This approach also

simplies service

and maintenance

requirements.

Figure 2. Larger UPS modules leverageeconomies o scale to drive down the costper kW.


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ability o IT and network managers to adaptto the requirements o modern applicationsand IT equipment, including servers, routersand switches that can handle either 120V or208V power with no modications necessary.

I decentralized power protection is used,be sure to account or UPS losses whendetermining room power requirements.

Determining Network HardwareRequirements

Network hardware required or convergedapplications will require a high-availabilityinrastructure that may have more incommon with systems used in the datacenter rather than those traditionally used in

network access rooms.

Achieving High Availability Protection

High availability protection or network accessrooms can be realized through deployment oreliable, fexible and cost-eective solutionsthat provide necessary levels o power quality,power reliability, cooling and ventilation,remote monitoring and management,physical security, and preventive maintenanceand rapid response service.

In many instances, most o this criticalnetwork equipment will be stored together ina rack. Its imperative to use a rack equippedwith ease-o-use design fexibility that allowsor the quick installation o new technologies.Physical security will be enhanced with alocking door, which should be perorated toimprove airfow to reduce heat, helping toensure higher availability.

Power QualityThe criticality o the network equipment willdetermine the type o UPS required. Doesthe network equipment only need powerbackup during outages or does it requirecontinual power protection and conditioning?

Again, VoIP may elevate network criticality.Whereas power availability or phonesystems was traditionally provided by phonecompanies, today it is the responsibility of eachorganization. Converged applications should

be supported with higher power availability up to 99.9999 percent to withstandbetween 31 seconds and 5.2 minutes o totalannual downtime.

Most general network access applicationsuse a line-interactive UPS, such as the LiebertPSI. This type o UPS provides extendedbattery capacities, some power conditioning,and delivers solid backup power protectionor a wide variety o applications i ull powerconditioning or a ault-tolerant design is

not required.

For business-critical, always-on applications,a true online, double conversion UPS, suchas the Liebert GXT, is a preerred choice.A double conversion UPS delivers a lowertotal cost o ownership, provides highlyeective power conditioning, and relies lesson the battery system to correct or poweranomalies, extending battery lie. It alsoprotects against UPS component ailures,including premature battery ailure romoverheating, power overload and ailureo the internal inverter. True online UPS unitshave higher reliability than line-interactivesystems because they include a ault-tolerantdesign with an internal bypass that maintainspower during any o the above circumstances.

Midsize, three-phase UPS systems, suchas the Liebert NX (Figure 3), can providehighly reliable centralized power protectionor multiple network access rooms rom a

single location. These systems can introducecapabilities not available in smaller UPSsystems, such as sotware scalability, whichallows capacity growth without addinghardware, and uneven paralleling, whichpermits dierent size modules to operate in

3

High availability

protection or network

access rooms can

be realized through

deployment o reliable,

fexible and cost-

eective solutions

that provide necessary

levels o power quality,

power reliability,

cooling and ventilation,

remote monitoring and

management, physical

security, and preventive

maintenance and rapid

response service.


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4

parallel. These eatures work together toenable a clear, easy-to-manage path oradding capacity or redundancy.

Power ReliabilityReliable power is the lieblood o ullyunctioning network access rooms. Based onthe increasing criticality o applications relyingon the technologies powered in these rooms,any power abnormalities have the potentialto thwart business continuity. Thereore,

several important considerations includingUPS sizing, runtime requirement, powerdistribution and power redundancy, must beevaluated to achieve desired levels o powerreliability.

UPS SizingWhen sizing the UPS or a network accessroom, use ull load calculations or protectedequipment to help ensure adequate powerand allow or growth. Some organizations use

nominal loads or estimate their average loads,which could result in undersized UPS units

leading to critical equipment downtime. Withthe changing nature o network technologyand growth in power requirements, sizingthe UPS units to accommodate a 50 to 100percent growth actor is not excessive.

I PoE is being used, power usage calculationsmust account or the inline power to thenetwork devices (Figure 4). Remember thatPoE draws could grow rom the current 15watts per port to 40 watts per port as newPoE standards emerge. As a result, powerdensities in network access rooms are otenthree to ve times greater than traditionalnetwork equipment, which will require largeror additional UPS systems.

Runtime RequirementsRuntime requirements will vary based onequipment criticality. Organizations wantingto support graceul shutdown o equipmentmay only need a ew minutes o runtime.Conversely, organizations wanting to ensurecontinuity o critical applications may needtwo hours or more, which requires additionalbatteries. Its important to note that batterysystems may require additional space iextended runtime (beyond ve minutes)is required.

Power DistributionPower distribution is important or ensuringpower reliability. Rack-level power distributiounits (PDUs) provide basic receptacle-levelpower distribution and high capacity designsor high-end switches.

Additionally, intelligent power strips cansupport remote power control as someproducts provide on-o operation oindividual receptacles. This eature can be

used to limit how much equipment is plugged

Cisco Catalyst Model Data Power (Watts) PoE Ports PoE Power (Watts) Total Power (Watts)

4503 405 48 830 1235

4507r 920 144 2491 3411

4510 1200 288 4962 6162

Figure 4. Using Power over Ethernet changes network access room power requirements.

Several important

considerations

including UPS

sizing, runtime

requirement, power

distribution andpower redundancy,

must be evaluated

to achieve desired

levels o power

reliability.

Figure 3. The Liebert NX is a midsize,three-phase UPS designed or scalability.


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into the UPS, reducing the risk o circuitoverload and ensuring that only authorizedequipment can be powered up.

Power RedundancyPower redundancy has become more

important with the growth o high-availabilityapplications as organizations seek to reducesingle points o potential ailure. Most networkequipment now comes with multiple powercords to support redundancy. A redundancystrategy should be driven primarily byavailability requirements.

In a single UPS conguration (Figure 5),both cords are plugged into the same powerdistribution unit, which is then plugged into a

single UPS connected to the wall outlet. Whilethe UPS provides backup i the utility powerails, there is no UPS redundancy in case theUPS ails.

To protect against UPS ailure, one cord othe rack equipment may be plugged into thewall receptacle, with the other cord pluggedinto the PDU connected to the UPS (Figure6). This conguration allows incoming powerto provide redundancy in the event o a UPSailure but exposes the network to potential

utility loss.

Using a single UPS with a maintenance bypassand power distribution switch is a low costway to protect against utility loss. With thisconguration, each equipment cord goes toa separate PDU with each PDU plugged into

the maintenance bypass switch (Figure 7).One cord rom the maintenance bypass switchis plugged into the wall and the other cord isconnected to the UPS.This conguration allows power to be providedrom the UPS to rack equipment in the event

a utility power outage occurs. Power can alsobe provided rom the wall i a UPS ails or whilethe UPS is being maintained. Although thissolution is certainly better than a standalone UPS,it does not provide UPS backup redundancy.

For true high availability applications, UPSredundancy should be considered. Figure 8shows a power redundancy congurationthat can be deployed in network closets;the conguration includes a PDU positioned

between the protected devices and the UPS.The highest availability is achieved with adual bus system. With this conguration,equipment cords are plugged into separate

5

Figure 6. Single UPS with utility power.

Figure 5. Single UPS confguration.

For true high

availability

applications, UPS

redundancy should

be considered. The

highest availabilityis achieved with a

dual bus system.

Figure 7. Single UPS and Maintenance BypassSwitch.

UtilityOutlet

UtilityOutlet

Liebert UPS

Liebert UPS

Liebert MP Advanced Power Strips

Liebert MPAdvanced

Power StripNetwork Switch

Liebert MicroPODWith maintenance

bypass switch

Risk of utility loss

Liebert UPS

Liebert MPAdvancedPower Strip

Network Switch

UtilityOutlet


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PDUs and the PDUs are plugged into separateUPS units. In turn, the UPS units are plugged

into separate circuits. A dual-bus congurationprovides UPS backup redundancy during apower outage and up to nine 9s o poweravailability, which translates into just 3/100 oa second o potential downtime each year.

Cooling and VentilationTodays power-hungry switches generatemore heat than previous generations oequipment. As a result, rack temperaturesoten exceed sae operating levels and

because the heat will not dissipate, it must beremoved rom the rack and the room. Heatthat is not removed will be drawn back intothe rack.

Cooling requirements depend primarily onthe equipment type and room size. In caseswhere switch power requirements are low,

simple ventilation may suce. Higher densityequipment will typically require a dedicatedcooling system. In act, the Uptime Institutehas reported that equipment located in thetop one-third o a data center rack ails twice aoten as equipment in the bottom two-thirdso the same rack. The organization estimatesthat or every increase o 18 degrees F above70 degrees F, long-term electronics reliabilityalls by 50 percent.

When determining cooling requirements,those responsible or the environment shouldevaluate the existing cooling system as notedpreviously, and determine whether the spacehas dedicated air conditioning or relies on thebuilding air conditioning system or ventilation

When planning the cooling system, determinwhether the door, ceiling or walls can supportductwork or ventilation and whether the heacan be exhausted to the outside. I the closetis cooled by the buildings air conditioningsystem, cooling is probably insucientbecause building air conditioning systemscycle on and o and do not run throughoutthe year.

Figure 9 shows options or cooling andventilation. For equipment loads o 100watts to 1,000 watts, ventilating the closetspace should be adequate. This should beaccomplished without compromising thephysical security o the space, which mayrequire the installation o intakes and exhaustgrills on the closet door.

Figure 8. UPS redundancy with the dual-busapproach provides the highest availability.

When planning the

cooling system,

determine whether

the door, ceiling or

walls can support

ductwork orventilation and

whether the heat

can be exhausted to

the outside.

Total Heat Load Recommended Cooling Solution

< 100 Watts Leaks and wall conduction

100 1000 Watts Intakes and exhaust grilles in doors or walls

1000 5000 Watts Dedicated cooling with remote heat rejection

> 5000 Watts High heat density cooling with remote heat rejections

Figure 9. Cooling requirements are determined by equipment power consumption.

UtilityOutlet

UtilityOutlet

Liebert UPS

Liebert UPS

Liebert MPAdvanced

Power Strip

Liebert MPAdvanced

Power Strip

Switch


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7

Rack ans provide another inexpensivemethod o removing heat rom equipmentwith the closet ventilation removing it romthe space.

Rooms with more than 1,000 Watts

o equipment will need some orm odedicated cooling. Sel-contained cabinetsor rack enclosures, such as the LiebertMCR (Figure 10), are available that includesupport systems such as computer grade airconditioning, a UPS, monitoring capabilitiesand security eatures. I rack power is likelyto exceed 5 kW, a high heat density coolingoption such as the Liebert XDF (Figure 11)may be best, although the system will requireproper ventilation o the closet space toremove condenser heat. This energy-ecientsolution utilizes digital scroll compressors toautomatically match cooling requirements tothe heat load at any time, which ensuresthe cooling unit is not always running atull capacity.

Remote Management and MonitoringWhile most organizations want to minimizethe cost o physically inspecting andmaintaining equipment in network accessrooms, they want to be able to detect

any adverse trends beore they turn intoemergencies. Remote monitoring andmanagement sotware has the capabilityto identiy adverse changes in theenvironment and equipment, including shitsin heat and humidity, water leaks, fuctuationsin UPS input power, declines in batterycapacity, and changes in runtime and outputload percentage, as well as coolingequipment status.

Network management sotware can be usedto determine the status o cooling equipmentand automate the graceul shutdown o

equipment in the event o a prolonged poweroutage. It can also reboot network equipmentand control power usage at the rack PDUreceptacle level to ensure adequate totalcapacity. For example, the Liebert Normmanagement sotware can initiate sae

shutdown o critical equipment i absolutemaximum temperatures are reached withinthe network closet.

For organizations using network managementsoftware, communication cards are availablethat allow power (including batteries) andcooling equipment data to be compiled andanalyzed (Figure 12). This tool also providesthe ability to remotely cycle the UPS on ando. In addition, small monitoring units canbe integrated into the system to provide

Figure 10. Sel-contained cabinets providean easy-to-deploy integrated power andcooling solution or low heat density networkaccess equipment.

Network management

sotware can be used

to determine the status

o cooling equipment

and automate the

graceul shutdowno equipment in the

event o a prolonged

power outage. It

can also reboot

network equipment

and control power

usage at the rack PDU

receptacle level to

ensure adequate total

capacity.


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real-time monitoring o temperature andhumidity changes, contact closures andwater leaks.

Physical SecurityBecause network access rooms escapethe scrutiny common to computer rooms,physical security is oten a major issue. This iswhy it is important to make sure ventilation isnot dependent on keeping doors open, whichcould allow unauthorized access. Simply, it isimportant to secure access room doors andsecure equipment inside lockable cabinets.Also, various mechanical locking systems areavailable to enhance the physical securitywithin network access room cabinets. Some

cabinets include easy to use 3-cylinder

combination locks to control access, withoptions available that allow access to bemonitored via the customers network.

Preventive Maintenance and RapidResponse Service

Preventive maintenance and service arecritical to ensure the availability o networkequipment. A number o options are oeredto help meet maintenance and availabilityobjectives, including maintenance bypassswitches, environmental monitoringproducts, warranties, and remote monitoringand on-site services.

When selecting network access roomequipment, it is essential to understand the

parameters o the product warranty. I acomponent ails, will the company replacethe UPS overnight via 24x7 customersupport? And, will the warranty covershipping both ways?

Some companies oer inexpensiveone- and three-year extended warrantiesat the time o purchase that can costeectively lengthen the lie o the UPS.Depending upon the warranty, on-site andpreventive maintenance services may be

included, with remote monitoring and otherservices also available.

Figure 11. The Liebert XDF is a securedenclosure with integrated high heat densitycooling, providing the benefts o big roomsupport. Optimized horizontal air circulationcools the protected equipment both instandard and backup ventilation modes.


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Conclusion

Network access rooms present a challenge asar as power and cooling are concerned. In thisdynamic environment, it is important to sizeand scale the power and cooling solutions or

fexibility and uture growth. Organizationswith business-critical applications will likelybenet rom dual bus redundancy, whichcreates parallel power paths to eliminatesingle points o ailure. Organizations that areonly concerned about utility power loss maybe able to unction with a single true onlineUPS.

Whatever the level o power redundancy,the network access room must be properlycooled and ventilated because heat willnot dissipate and will be drawn backinto the rack i it is not removed. To keepequipment operating at peak perormance,a variety o remote monitoring andmanagement sotware is available thatcan detect environment and equipmentchanges beore adverse trends turn into

emergencies. Organizations can also benetrom preventive maintenance and serviceagreements, including extended warrantiesthat are cost eective and can help lengthenthe lie o the UPS.

Organizations with

business-critical

applications will likely

benet rom dual bus

redundancy, which

creates parallel powerpaths to eliminate

single points o ailure.

Organizations that are

only concerned about

utility power loss may

be able to unction

with a single true

online UPS.

Other26%

Utility/Generator 4%

LogicBoard 4%

UPSComponents 4%

CircuitBreaker 4%

OtherExternal 6%

REPO/EPO 8%

User Error 7%

End of Discharge19%

Bad Batteries18%

Figure 12. Battery problems (37 percent) represent the largest cause o UPS ailure and can beminimized through UPS consolidation or remote battery monitoring.

Top Causes o UPS Failure


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AVAILABILITY CONSIDERATIONS

YES NO

Do you know what level o power availability you require in your network access room? o oI not, have you calculated your cost o downtime or network access room equipment to help

determine your desired availability level?

o o

PHYSICAL ENVIRONMENT CONSIDERATIONS

Physical Size YES NO

Can you t all your desired network equipment - including power and cooling systems intothe rack?

o o

Can you t the rack into the room? o o

Existing Power YES NO

Is there sucient incoming power or your ull equipment loads? o o

Are there sucient circuits or redundancy i desired? o o

Have you checked which types o receptacles are present will they accommodate equipmentplugs types?

o o

Existing Cooling and Ventilation YES NO

Is the room ventilated? o o

I not, can it be ventilated to the outside? o o

Does room cooling dedicated or building cooling exist? o o

APPLICATION AND HARDWARE CONSIDERATIONSPower Quality YES NO

Will you equipment need power protection during outages only or continual protection andconditioning?

o o

Power Reliability Backup Runtime YES NO

Are you using ull loads and not nominal loads to size the UPS? o o

Have you sized the UPS based on actors such as Power over Ethernet, network equipmentgrowth, and the criticality o the equipment?

o o

Power Reliability - Distribution YES NO

Do you require basic rack PDUs those with multiple receptacles? o o

Do you require rack PDUs with monitoring and control capabilities? o o

Do you need to maintain tighter controls over who makesequipment changes?

o o

What levels o power and UPS redundancy do you need given the criticality o your equipmentand your cost o downtime?

o o

Appendix A

Network Access Room Review Checklist


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11

Power Reliability Power Redundancy YES NO

What levels o power and UPS redundancy do you need given the criticality o your equipmentand your cost o downtime?

o o

Physical Security YES NOIs your network access room secure rom physical entry? o o

Do you need to secure cabinets rom unauthorized entry? o o

Do you want to be alerted when the cabinet is opened? o o

Cooling and Ventilation YES NO

Will the equipment you install require dedicated cooling equipment? o o

Is power consumption 4kW or more - high enough to consider high-density dedicatedcooling?

o o

What are the cooling requirements o your network equipment planned and anticipated? o o

Monitoring & Management YES NO

Do you use network communications sotware? o o

Do you want to monitor power and cooling equipment via your network? o o

Do you want to be able to send alerts, initiate graceul shutdowns o equipment or and control

power usage within the rack?

o o

Preventative Maintenance & Rapid Response Service YES NO

Do you want to be able to service the UPS without shutting down power to theprotected equipment?

o o

Do you want to protect your UPSs with warranties beyond 2 years? o o

Do you need UPS and battery checks or other types o preventative maintenance? o oDo you need startup services or larger UPSs and cooling systems? o o

Do you want to consider a long-term warranty and service package to provide preventativemaintenance and repair or up to 5 years?

o o


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Emerson Network Power.The global leader in enabling Business-Critical Continuity. EmersonNetworkPower.com

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Emerson Network Power

1050 Dearborn DriveP.O. Box 29186

Columbus, Ohio 43229

800.877.9222 (U.S. & Canada Only)

614.888.0246 (Outside U.S.)

Fax: 614.841.6022

EmersonNetworkPower.com

Liebert.com

While every precaution has been taken to ensure

accuracy and completeness in this literature, LiebertCorporation assumes no responsibility, and disclaims allliability or damages resulting rom use o this inormationor or any errors or omissions. Specications subject tochange without notice. 2008 Liebert Corporation. Allrights reserved throughout the world. Trademarks orregistered trademarks are property o their respectiveowners. Liebert and the Liebert logo are registeredtrademarks o the Liebert Corporation. Business-CriticalContinuity, Emerson Network Power and the EmersonNetwork Power logo are trademarks and service marks oEmerson Electric Co. 2008 Emerson Electric Co.

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