AE Newsletter Volume 5 -

Always Free Issue No 5

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Welcome to the 5th Issue of the Precision Cooling AE Newsletter! There are a lot of exciting things on the horizon but one of the

most riveting is the new DA125 unit within the DSE product family. Early site feedback from Field Trial sites has been incredibly positive with regards to energy consumption, condenser sound, and cooling uniformity/consistency.

For those of you unfamiliar with this product, the DA125 is a completely new unit that we are currently offering for Field Trial site installations with a full production release in the early June time frame. It has several nice features that are being incorporated:

1.) DX dual stage R410A high efficiency coil 2.) Tandem Scroll/Digital Scroll compressors 3.) EC plug fans 4.) Electronic Expansion Valves 5.) Pumped Refrigerant Economizer utilizing VFD refrigerant

pumps 6.) New global condenser

The combination of all these features allow the DA125 to achieve SCOP values that significantly exceed the

newest ASHRAE 90.1-2010 requirements.

One of the biggest energy saving features of this unit is the EconoPhase option. This economizer is different from a Glycool DS unit because instead of using a separate glycol coil upstream of the DX coil in the airstream, it uses the systems R410A as a VFD pumped two phase refrigerant (without compressor operation) within the same DX coil that is typically used during DX operation with the tandem compressors. With the larger high efficiency coil this economizer can achieve 100% system capacity (125 kW) at approximately 35

F outside ambient while only

consuming roughly 12 kW for the VFD refrigerant pumps, EC fans, and condensers combined. Using a single coil also reduces the fan energy required. Partial loads require far less system energy. In one of the Field Trial sites a PUE of 1.08 was recorded in EconoPhase operation.

Your Precision Cooling AE can help you quote up these DA125 units today. Refer to AMP for additional

information, presentations, and manuals!

A.E. NEWSLETTER EMERSON NETWORK POWER LIEBERT PRECISION COOLING / February 2012

Editor Tyler Voigt, Senior Application Engineer

L R S

Pages 2-5 SFA Spotlight Dual Power SFAs

Pages 6-9 Technical Effects of Elevation

Pages 10-12 LRS Update

Page 13 Welcome Medin and Bill!

Page 14 Fun Stuff


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Pulling back the curtain on the available list of SFAs once again, it is the SFA Spotlight on Dual Power & Dual

Disconnect Options for current product offerings. Often specifications arrive with generic requirements for dual or redundant power options. These requirements can be exclusive to the indoor equipment or extend all the way to the heat rejection devices and pumps. The ambiguity in these requests often causes confusion from beginning to end during the evolution of the job. In an effort to clear up confusion associated with the dual power combinations that are available, listed below are different options for applying dual power features to several products. The SFAs include separating internal loads onto two power supplies (reduced load on two sources), dual disconnects for redundant power scenarios (two separate power supplies, the backup will operate the unit during an outage of the primary), accessory SFAs (options to increase the features on the base dual power SFAs) and the Single Point Solution. Not all unit sizes, types or options can utilize these SFAs, as many of these SFAs are very specific to the unit and components that can be included on a unit. Pay close attention to the limitations or you can always contact your Precision Cooling Application Engineer for help with a solution.

For customer sites that have reduced power available per feed to the equipment (typically due to UPS or

generator sizing) we can offer the following solutions to break component loads onto separate power sources.

E-4218: Two power blocks for dual power supply Applicable to Challenger, Liebert DS, Liebert CW This SFA removes the disconnect switch (s) from the unit. They should be field supplied and wired.

E-3886: Unit built with six pole disconnect for dual power supply Applicable to Liebert CW, Challenger, 8 Ton Minimate, or DX units where 60 amps is not exceeded on either side. This SFA provides a single disconnect switch to power the entire unit. Using a CW unit as an example: the fan and controls on one source, reheat and humidifier on the other source all through one six-pole disconnect switch.

E-23799: Liebert DS unit to be built with dual disconnect switches for two power input feeds, no switchover Applicable to Liebert DS only Uses either locking or non-locking disconnect switches, allowing unit loads to be separated onto two sources provides for a disconnect switch for each source. Typically SFA E29786 is used in conjunction with this SFA to stage compressor restart after power is restored if a UPS/generator will be providing back up power to the compressor circuit to limit the amount of in-rush current.

E-9075: Liebert CW units with dual disconnect switches for two input power feeds, no switchover Applicable to Liebert CW only The variations of this SFA depend on unit size and disconnect types.

Before reviewing the list of dual disconnects and reversing starter SFAs, we need to define a few key terms associated with them:

Dual disconnects means there will be two disconnects on the unit. Each disconnect will be connected to a

separate source of power, providing power to the unit components from the active power source. Reversing starter is a relay that can switch between power sources in a few milliseconds. It operates like a

small, featureless transfer switch. If there is no delay on the switching mechanism, the units control will be unaware of the switch to the secondary power source due to the speed of the switchover. However, some SFA variations feature time delays to prevent nuisance switching. Switching back to the primary source from the backup typically has more of a delay which could reset the iCOM controls.

SFA Spotlight: Dual Power and Dual Disconnect Options for Cooling Units

Matt Getridge, Newly Promoted Senior Application Engineer


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Manual reset to primary refers to manually resetting the unit back to primary power when the primary power source is restored. Whichever source is powered to the unit first will become the primary power supply. To reset the unit, a person can cycle off both disconnects, engage the primary source first and then engage the secondary source. This is required when both power sources are always on utility sources and you want to designate which source is the primary to the unit. The unit will also re-designate power source #1 as the primary if it is available and the backup (generator) power source is removed. In most cases this is sufficient given the secondary source will typically be removed on the building level after the utility or main source of power is restored. The generator controls are handled on the building side.

Automatic return to primary will automatically switch the unit back to the primary source once the primary

source has been restored even when the backup source is available. That is to say, there is no need for anyone to cycle the unit disconnects off and reset the unit back to primary, as described in the Manual reset to primary; even if both sources are lost and then returned at different times.

When the specification calls for dual power inputs with a switch to backup or secondary power, the SFAs

below can satisfy the requirement. There are several variations that are applicable across the entire product catalog, but each carries its own limitations. It is important to note these, so as not to over promise and under deliver on this key provision in specifications. In most cases, Liebert CW can support just about any of these SFAs with the exception of 48 long units (CW026, CW038, CW041), as there is not enough space in the unit for two disconnects and a reversing starter. A solution for these units is to upsize the frame via another SFA which will provide the additional space needed. On Liebert DS/VS and Challenger units, space constraints make dual disconnects with a reversing starter difficult, although there are a few solutions available for specific models. Condensers, drycoolers and pump packages also have options for dual power sources with power switchover with several restrictions and limitations.

E-6289: Dual disconnect switches with a reversing starter and a selector switch to set the type of switchover Applicable to Liebert CW This SFA carries several limitations based on unit size. Indicator lights, status contacts to indicate source, pneumatic timers for delayed switchover can all be included. The selector switch will allow switchover to be automatic or remotely initiated; the reversing starter can only provide 27 amps through the secondary side.

E-9107: Dual disconnect switches with reversing starter, manual reset to primary Applicable to Liebert CW Liebert CW 48 units will need an upsized frame to accommodate this SFA. The secondary power supply limited to 27 amps through reversing starter. This SFA can be offered with lights and contacts to indicate source currently in use. Other accessory SFAs can be combined with this one for added features. Refer to the Applications page on PartnerWeb under SFA s: Details, Features & Operation for more information on the operation of this SFA. This SFA is often combined with E-7260 (see below).

E-33398: Dual disconnect switches with reversing starter, manual reset to primary Applicable to Challenger split system evaporator or CW only In addition to the limited type of Challenger, this SFA limits the unit voltage to 380, 460 or 575V and requires the unit does not have any reheat option. This SFA operates the same as E-9107.

E-23749: Dual disconnect switches with reversing starter, manual reset to primary Applicable to Liebert XDP This SFA automatically switches to secondary upon a loss of primary power and can be configured to include lamps to indicate which power source is in use.

E-33253: Dual locking disconnect switches and reversing starter, manual reset to primary Applicable to Liebert DS This SFA requires the FLA to be less than 80 amps and OPD to be less than 100 amps on a Liebert DS/VS unit with 208, 230, 460 or 575V input power. No reheat and no humidifier is allowed on the unit (cooling only).


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E-29959: Dual disconnect switches with reversing starter, timer to delay switch to secondary power upon failure of primary power supply

Applicable to Liebert CRV only This SFA can only be applied to Liebert CRV CW models without reheat. The iCOM quick start function and auto or

manual return to primary power can be added. Refer to Volume 4/Issue 4 (October, 2011) edition of the Precision Cooling AE Newsletter for more details about this SFA.

E-32269: Dual disconnects with reversing starter, automatic return to primary power Applicable to Liebert CW 97 frame size and larger This SFA provides primary and secondary power to all high voltage devices, and includes pneumatic timers on both sources to delay switching between sources. Also included are customer contacts and status lights to indicate current power source in use. Units that use this SFA must have an FLA of less than 85 amps. This SFA is similar to combining SFAs E-9107 & E-7260 (see below), but with the addition of a second pneumatic timer on the secondary side to delay the return to primary power.

DC-27194: Remote power supply transfer box with reversing starter, automatic return to primary Applicable to Fan Speed Control, Variable Frequency Drive, Lee Temp Condensers, or Fan Cycling Drycoolers only The current variation of this SFA is limited to 460V / 60Hz only and the unit must be ordered with a disconnect switch. This SFA provides a ship loose, field mounted remote box without disconnect switches -- they can be ordered separately or provided in the field for the box. The SFA includes an adjustable time delay to delay switching between primary and secondary, with an automatic return to primary when it is available. Normally open contacts are provided on each power supply for remote indication of the source in use.

DC-1022: Dual pump controls in weather proof enclosure, separate power feeds for each pump with automatic switchover to secondary source and secondary pump upon loss of primary power

Applicable to Dual Pump Package Control Panels This SFA for a dual pump control panel will switch to the secondary power source that powers the second pump if the first pump loses power or flow. If power is restored to the primary source, the control panel will switch back to the primary source and pump. If the primary pump is not capable of providing flow, the panel will switch back to the secondary source and pump. When the secondary pump and source are in use a customer contact will close indicating the secondary pump is in operation. There are also variations of this SFA that will provide dual power supplies on the control transformer as well as the pump power supplies. It is worth mentioning that other pump control SFAs also feature automatic switchover to a secondary power source and pump, but they are variations on a different concept. For instance, DC-896 for a dual pump control and 42 day lead/lag timer can be configured with a dual power, auto switchover option, but this is a small variation on the main intent of the SFA: to provide a 42 day lead lag timer. Contact your Precision Cooling Application Engineer if you would like to explore dual power options on other pump control SFAs.

Note: Liebert CW146 & CW181 units include an optional pricebook feature for dual disconnects with a reversing starter. This optional feature matches the design and operation of SFAs E-9107 & E-7260 (see below).

There is also an SFA that provides a single disconnect that can accept two sources. The SFA is non-

automatic, it will not switchover to the secondary source on a loss of primary. However it does allow two sources to a single disconnect allowing either source to power the entire unit.

E-6104: Unit with manual selector switch, disconnect to allow either source to power the unit with a center off position

Applicable to Liebert CW, Liebert DS/VS and Liebert XDC This SFA provides a single disconnect switch connected to two separate power sources to allow either source to power the entire unit. The disconnect switch will have a center off position. A manual switch between the two sources is required.


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The following SFAs can be combined with a few of the dual disconnect SFAs above to get different accessory options included with dual disconnects and a reversing starter.

E-4230: Under voltage and phase loss monitor protection relay to turn off the unit upon detection

E-7260: Pneumatic timers to delay switchover, auxiliary contacts and lamps to indicate source in use, automatic return to primary, compressor lockout when on backup source and more

E-7319: High withstand short circuit disconnect for Liebert DS, Challenger and Liebert CW Soon to be a standard option on several products

E-30781: High withstand short circuit disconnect for Liebert CRV

E-30832: High withstand short circuit disconnect for Liebert XDP

E-32827: Customer contact wired to remote alarm to indicate loss of primary power when the unit is on secondary power

Notice that Minimate, Datamate, Intellicool and XD evaporator modules are decidedly missing from the above list of SFAs. Generally this is due to space limitations within each units electric panel or frame. In the case of the XD evaporator modules, the XDV and XDH both feature dual redundant power inputs with automatic switchover as a standard feature. The design of the Liebert XDC makes fitting dual disconnects and a reversing starter impossible. If a single disconnect with dual power inputs is acceptable for the Liebert XDC, use SFA E-6104 (see description above).

Finally, if the combination of SFAs above cannot satisfy your needs or if the pricing on a per unit basis is just

too great, there is a simplified solution. By comparison, the Single Point Solution is more robust, better engineered for the task and can be sized for a number of units.

E-27386: ASCO 4000 Series automatic transfer switch in a 1(C)-NEMA 1 enclosure This ATS can be sized to provide backup power to a number of units in lieu of dual disconnects with reversing starters on the individual units. If dual disconnects are not available on the unit that you are bidding or the combination of features prevent dual disconnects from being applied -- this SFA is the only (and perhaps best) solution. Refer to the

Applications page on PartnerWeb under SFA s: Details, Features & Operation for more information on this drop shipped product.

So there you go! The most up to date list of dual power, dual disconnect, reversing starter and accessory SFAs that are currently available. Remember that SFAs change, not only in pricing, but in design and function. Be sure to contact your Application Engineer for the latest features and options associated to these SFAs and how they apply to each product before committing to these SFAs on any of your projects. Great selling!


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Did you know that the Colorado Rockies Coors Field has the record for most home runs in a MLB park? The record is 303 homeruns set in 1999.

One factor that played into this hitter-friendly park is its elevation at 5,280ft. At a mile high Denver has an air density that is 82% of that at sea level (densities shown below in Figure 1 at 70

F). Air density varies directly and linearly with temperature, and inversely

and exponentially with altitude. Therefore; the denser the air the more drag imposed on an object traveling through the air.

Figure 1. Comparison of air densities at 1 mile high and sea level

Air density not only affects a baseball game but can also affect the performance of chilled water or DX coils.

An important thing to keep in mind is that most manuals publish capacities at sea level. When designing for an elevation other than sea level, capacities need to be re-calculated. Using the following equations you can derive a Sensible Heat equation to make this process easier.

First we will calculate the mass flow rate of the air:

Where:

Now to calculate the sensible heat transfer for a given amount of time -> :

by substituting the equation from the previous section

Where:

Effects of Altitude/Elevation Nick Swathwood, Newly Promoted Senior Application Engineer


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Since the

,

( ), and

( ) are constants (for sea level) we can multiple them to get

.

This is commonly referred to as the CFM transfer factor (different values at different elevations shown in Table 1).

This leaves the final simplified equation to figure out the sensible heat transfer for a given amount of time -> Q in

:

And in our terms:

This quantity in our case will be negative. The negative sign signifies heat is being taken out of the air. Using Table 1 below, the capacity loss can be calculated using varying CFM transfer factors based on elevation.

Table 1 - Altitude Correction Factor for Air at a Constant Temperature = 70F

Altitude Barometer Specific Volume

Relative Density Air Density

CFM Transfer CFM

feet Inches Mercury

lb/in^2 ATMOSPHERE

ft3/lb SP or HP Corr Factor

lb/ft3 Factor Correction Factor

0 29.92 14.70 13.340 1.000 0.0750 1.080 1.000

1000 28.85 14.20 13.834 0.964 0.0723 1.041 1.037

2000 27.82 13.70 14.327 0.930 0.0698 1.005 1.075

3000 26.81 13.20 14.687 0.896 0.0672 0.968 1.116

4000 25.84 12.70 15.434 0.864 0.0648 0.933 1.157

5000 24.89 12.20 16.035 0.832 0.0624 0.899 1.202

6000 23.98 11.80 16.695 0.799 0.0599 0.863 1.252

7000 23.09 11.30 17.234 0.774 0.0581 0.835 1.292

8000 22.12 10.90 18.050 0.739 0.0554 0.798 1.353

9000 21.38 10.50 18.657 0.715 0.0536 0.772 1.399

10000 20.57 10.10 19.418 0.687 0.0515 0.742 1.456

Example: If an engineer designed a project for sea level and the end user decided to relocate the build to a new site at 6,000 ft. elevation how much capacity loss will the new site experience using the existing design? Given:

Find:

Solution:

CFM Transfer Factor


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Remember this is negative because heat is being transferred out of the air.

Therefore:

This means that 64,449 more

will be transferred out of the air at sea level than at 6,000 ft. elevation.

Therefore building the site at a 6,000 ft. could mean the equipment previously specified might not be sufficient.

You could also take the ratios of the CFM Transfer Factors between the two elevations to see how much capacity you will be short:

Let us do the same example using the Liebert Rating System (LRS).


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In the above example we had to lower our water flow rate to maintain the of the air but left all other conditions the same. So why did the BHP drop between the two elevations?

Since a fan is a constant volume device for a given RPM and static pressure, the fan volumetric air flow (CFM) is not affected by air density changes. With this in mind adjusting the RPM will correspond to a change in CFM. The fan motor however is affected by both RPM/CFM and air density.

Below are the Liebert Blower Program runs for the above example. Notice the differences between the two runs.

Centrifugal Fans Elevation at 0ft, sea level

Elevation at 6,000 ft.

SCFM is Standard CFM whereas ACFM is the Actual CFM. The easiest way to explain the difference between the two is that SCFM incorporates the actual heat transfer capability (based on mass flow rate) of the air moving at sea level conditions whereas ACFM is the actual amount of air moving (based on volume). At elevation the ACFM has to be increased to get the same heat transfer (thermal mass movement) as to what you have at the denser sea level. Using the example above the blower is moving 16,500 CFM, however at sea level it would have the equivalent heat transfer capability as a unit moving 13,240 CFM. That is why the first thing you will notice when you are sizing drives for higher elevations, the drive is typically sized larger to push more ACFM so that you get the same heat transfer of the SCFM at sea level.

What can you take from this article? You need to be sure elevation is considered when sizing units for job sites. If it is not, the units could be short on capacity (assuming the elevation is above sea level). Because air is less dense at higher elevations more airflow is required to reject the same amount of heat. This has all been made easier with the use of LRS and the Blower Program. Inputting the ACFM is all that is needed and the programs will do the rest. In addition to the programs you now have a Sensible Heat transfer equation to use as a reference for future higher elevation jobs.

Air density ratio = 16500/16500 = 1.0

Air density ratio = 13240/16500 = 0.8

Why did the 0.20 of ESP increase to 0.25? When entering the ESP you do so at the ACFM. Sizing the drive package is based on SCFM so the ESP gets converted to add to the ISP. = ESPACFM/Air Density ratio = 0.20 / 0.8 = 0.25

Due to the air density it takes less power to move the same amount of air at higher elevations.


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In the upcoming release of the latest LRS revision youll notice a new button in the options at the bottom of you LRS homepage. This new option will allow you to run performances for the new Liebert air cooled DA125A (DSE product family). Here is a little preview of what to expect since it will be a little different than the LRS to which you are accustomed. Once you have clicked the DSE Performance button, you will see a new project screen just for DA125A projects.

After clicking the NEW project button you will get the following project screen that allows you to enter some project details as well as define alternate unit selections. The next screen is similar to the unit definition screen in the current LRS, however each component selection is linked to the others. This means that for each selection made, the remaining options are reduced to only those available with the previous selections. At this time this section only currently applies to the DA125A so the available options are limited to that unit only.

L R S

LRS Update


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Once you have selected the unit options and click Next things will begin to look different. Now you will need to:

S#1.) Select unit performance level.

S#2.) Select the performance conditions.

S#3.) Click the Add Control button to add the control state to run.

Once you have added your control scheme, it will be added to the System Controls to be run. You can

continue to the performance run or add different controls schemes to run as well. You can add a run for different

capacity levels or different conditions and then click Add Control to add the new runs to the Systems Controls

section.

After all of your control schemes are added click Next and the actual performance runs will begin. Word of warning, the DA125A is a complex system to model and calculations will take some time. In the output example below you can see that with the two performance runs at 72F/50% RH, both 100% and 75% capacities were run at the same time.

S#1

S#2

S#3

System Controls


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The PRE (pumped refrigerant economizer) capacity performance is currently in development and will not be released with the DA125A performance in LRS. If you have any questions please contact your Precision Cooling Application Engineer.


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Recent changes in personnel have allowed us the chance to welcome two new members to the Precision Cooling Applications group. We would like to introduce these Precision Cooling AEs and give you a look into their background and personality.

Medin Ucubagabriel comes to us from the New Product Development engineering group. He is a 12 year Liebert vet and will support the DC, Connecticut, and Virginia FDO offices. During this time he helped participate in the design of the XD system. In particular he was heavily involved in the flexible hose options. The first thing you would notice about Medin is his height. He comes in at 63, making him the starting center for the Precision Cooling AE basketball team. Besides basketball, Medin also enjoys playing Frisbee golf (aside from the occasional ankle sprain sustained), real golf, working on computers, and spending time with his family. He has a BSME degree from The Ohio State University.

Medin is excited about his move to the Precision Cooling Applications group. He likes working on a variety of different projects on a daily basis and seeing how end-users actually use our products. He recently had the privilege of attending a 3rd party witness test in beautiful Cortland, NY and enjoyed the process of coordinating a test at a facility other than Liebert. Medin cites SFA E33319 (with Product Manager approval) as his favorite. Hes excited that we finally are able to offer EC fans in an upflow CW unit.

Bill Brown is in his 4th year of Liebert service and joins us from the Precision Cooling Support team. In his previous role Bill was a Field Service Engineer and participated in many quality improvement projects for Liebert equipment. Prior to joining Liebert, he obtained an AAS degree in HVAC and ran his own contracting company for 6 years.

Before tackling SFA requests and phone calls, Bill likes to start his day with a 5 a.m. workout at the gym. He also enjoys traveling, building furniture, and spending time with his family (including his soon to be one year old son, William IV).

Bill is looking forward to being a Precision Cooling Application Engineer and using his service knowledge to provide well rounded support to the rep offices of the Southeast. In his short time in the group, Bill (like every AE) is amazed at the variety of questions that come up about Liebert products. He is a big fan of SFA E31181 and E32047 which provide airflow to discharge out the bottom panel through the front or rear (or both). It is a simple idea, but sometimes simple ideas are the best, he says. We welcome both Bill and Medin to the group, and wish them luck (and sanity for as long as possible) as Precision Cooling Application Engineers!

Welcome Medin and Bill! Bart Holmes, Application Engineer


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Bart Holmes 4 Year Anniversary 1/1/2012

Nick Swathwood 6 Year Anniversary 1/23/2012

Bill Brown Birthday November 15

Bart Holmes Birthday November 23

Matt Getridge Birthday December 11

Medin Ucubagabriel Birthday January 8

Fun Stuff Jack Starcher, Senior Application Engineer


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Crossword Solution

Word Jumble Solution

Fun Stuff Solution for Issue #4

Documents

AE Newsletter Volume 5 -