OSP Cabinets

Brian L. Mordick, RCDDHoffman Enclosures

Agenda• Types of OSP Cabinets

– Wall, Pole, Pad Mounted• Materials

– Aluminum– Steel & Plated (Galvanized)

Steel– Composite (Polycarbonate,

Fiberglass, etc)• Applications

– WiFi, Cellular, POTS, FTTX, Security, LAN, etc

• Equipment– Hardened vs. standard

equipment

• Telcordia GR-487 & UL Type ratings– What it is?– How it influences costs

• Understanding Thermal Requirements to Avoid Extra Cost and to Run “Greener”– Thermal Management

techniques– Insulation– Color– Solar shield

• Summary

Outside Plant (OSP)• Pad-Mount• Pole-Mount• Exterior Wall-Mount• Vaults and tunnels• Roof Tops

Hardened vs. Standard Equipment• Hardened OSP Equipment

– Made for high temperatures – 125F– Withstands vibrations & impacts– Coated to withstand molds, corrosion, etc– Central Office, Cellular, and Military specifications– Developed to provide “Highest reliability”

Designed for OSP applications

• Standard “TE” / IDF equipment– Made for indoor controlled environments

85 – 95F max typical No protections for vibrations, impacts, moister, corrosion, etc

• The use of typical “TE” equipment for OSP environments is never recommended– Need to provide a protected environment inside the cabinet

OSP Materials• Aluminum

– Most common material (especially for Pad mount)– Light weight with corrosion protection

• Stainless Steel– Corrosion protection – coastal areas – Salt– Food, petro chemical, water treatment, others

• Painted Steel– Not usually used but could be for a low cost solution– Not well accepted by the OSP industry.

• Composite– Used mostly for WiFi, vaults and tunnels applications– Typically smaller Wall and Pole Mounted cabinets

Aluminum – Pole Mount

• Typical OSP application• 19” spaced equipment

rotated to reduce width of cabinet– Less load on pole

• Heat exchanger for thermal control

• Solar shield to reduce heat build-up

• Typical “Telco” equipment

Composite – Pole-mount

• Ideal for WiFi pole-mount applications

• Lightweight – Pole mounted applications

• Chemical resistant– Great for Petro-

chemical facilities• UL Type 3R, 4, 4X

– Some are Type 6 & 6P• Easy to drill cable entry

holes where needed

UL Type Ratings• UL has several Type ratings that are commonly

used for OSP cabinets– Type 3R – Protects against rain and dust

Not gasketed or sealed – Outside air mixes with equipment Example - Outside AC breaker box

– Type 12 – Indoor but can be used outdoor in moderate temperatures (No icing or Temps below 40F) Fully sealed from outside air penetration

– Type 4 – Protects against icing, rain, etc Fully sealed from outside air penetration

– Type 4X – Same as Type 4 but corrosion protections Stainless steel, Aluminum, or composite

– Type 6P – Submersions in water Rare but some times used in tunnels and vaults

Telcordia GR-487 PopularityIn the hundreds of OSP enclosure project applications

received by Hoffman every year, the de facto standard cited is frequently Telcordia GR-487

• Developed by the old Bell System • A good standard

– Performance based– Recently updated– Smorgasbord of tests– Ala cart of testing procedures

• Very expense when it is embraced in its’ entirety, withoutexceptions

What’s in Telcordia GR487?• Finish• Metallic Materials• Polymeric Materials• Lifting Details• Security/Alarms• Bonding & Grounding• AC Power• Exposure to High Temperature• Thermal Shock• Water & Dust Intrusion• Acoustical Noise• Firearms Resistance• Fire Resistance• Corrosion Resistance• Shock and Vibration• Seismic Resistance.............. and more

All this and more!“Ala Cart”

Only order what is needed

Hypothetical $8,000 Cabinet System

• To save capital expense:– Become more discerning regarding GR487– Consider your anticipated lifespan for the deployment,

the geography and climate – Don’t build a bullet-proof 25-year system if you

don’t need one

$0.00

$100.00

$200.00

$300.00

$400.00

$500.00

$600.00

$700.00

$800.00

HighTemp

Seismic Salt Fog TransVibe

Firearms PolymericMatls

Does not include the Lab Testing Cost!Seismic Testing - $15,000 alone

3.26 Exposure to High Temperature:• Ambient range

– -40C to +46C (-40F to +115F)

• Allowable interior range depends on equipment

• Effects of solar load must be included

• Unmitigated– This often times means

an air conditioner is the only solution

3.26 Exposure to High Temperature:• Steps to mitigate the cost:

– Careful selection of internal electronics (choose tolerant)

– Consider the temperature ranges in your geography

– Understand the cost for “worst case scenario”?

– Insulate the cabinet interior– Include solar shields– Choose light color

CR3-210 Seismic Earthquake Resistance:

• Select Zone 4 only if you must– Requires very heavy

cabinet construction Inset doors (Door jam) Heavy hinges & latches Thick mounting provisions Careful selection of vibration-

proof hardware Extra care at assembly and

installation.

• Cost are significantly reduced in Zone 3 or 2

R3-203 Salt Fog:• Salt Fog test is 30 days (720 hours)

– No visible evidence of corrosion can be present

• Requires costly components:– Stainless steel handles & latches– Stainless steel hardware on the interior

(racks, etc.)

• NEMA and UL Type 4X is 200 hours• To save costs, evaluate

– Your situation/ environment– Intended product lifespan Is this a failure?

R3-207 Transportation Vibration:• Rugged test per GR63

– Analogous to “driving down a rail road track for 30 minutes”

• Mitigation:– Invest in a “shock pallet”– Package critical electronic

components separately inside the cabinet, install them at final destination

– Use special blocking inside the cabinet to be removed at final destination

R3-200 Firearms Resistance:• Three levels of test:

– 12 GA shotgun– .22 Cal rifle– .30 Cal rifle

• Material performance: – .080 thick aluminum passes

shotgun– All practical thicknesses of

aluminum fail .22 Cal rifle– Composites and fiberglass fail

shotgun

• Mitigation:– Choose steel / stainless steel

16 gauge passes .22 Cal rifle

12 GA Shotgun.22 Cal Rifle (fail)

3.5 Polymeric & Non-metallic Materials

• Some of the most modern, commercially acceptable polymeric materials will not pass the entire criteria– Fire resistance– Insect sprays– UV & Ozone

• Mitigation: – Consider your

situation/environment– Determine most important

criteria

Standard GR- 487- CORE R3 -151

• Enclosure Solar Load Test– With equipment running– Ambient temp 115 F– Illuminate on three sides

with controlled light banks 70 W/sf

– Recorded internal temperature must be less than lowest rated component

Solar Absorption αs = 1- reflectance Surface Solar Radiation

(αs) absorption Polished Aluminum .15

White .14 Yellow .30 Cream .25

Light Grey, Green Blue .50 Med. Grey, Green Blue .75 Dark Grey, Green Blue .95

Black .97

Thermal Requirements• OSP Thermal management

requirements are very demanding

• Wide range of environments

• Many alternatives• Operating cost vs. up front

capital costs• “Green” initiatives• Noise ordnances• Equipment – Hardened?

Why it is important to size the Cooling System?

At Extreme Temperatures…• Shorten life of equipment• Poor reliability & performance• Rectifier performance is de-

rated • I/C based devices may

experience intermittent fluctuations in output and voltage migration

• Mean Time Between Failure (MTBF) decreases exponentially

• Catastrophic failuresA Digital Equipment Corporation Study shows, “For every 18ºF (10ºC) rise above normal room temperature, the life expectancy of the electronics is reduced approximately 50%

Heat Transfer - BasicsHeat Transfer is a Combination of :Conduction q=kA(t1-t2)/x

Convection q=hA (t1-t2)

Radiation q=F1F2AσT4

σ =1.713 x 10-9 btu/(hr-ft2-°R)

This CFD of a ventilated cabinet illustrates the temperature gradients

of approx. 20°C ( 36°F) within the enclosure .

MATERIAL BTU/H-FT2° F (k) ALUMINUM 117

CARBON STEEL 25 STAINLESS 9.4

WINDOW GLASS .45

Air Film BTU/H-FT2° F (h) St ill (Free Convect ion) .79 - 1.65

4.5 mph w ind or 6.5 f t /s 2.10 7.5 mph w ind or 11 f t /s 4.00 15 mph w ind or 11 f t /s 6.00 77.5 mph w ind or 114

f t /s 13.20

Convection – Air cooling• How to dissipate the Heat - Watts?

– Equation [ WATT’s = .316 X CFM x ΔT in F ] At Sea level (Use equation up to 4000 Ft)

– Air volume (CFM) The greater the air volume (CFM) the more heat removed Higher the CFM, the more heat dissipation

– Temperature {Delta T or ΔT in F } The greater the temperature difference the more heat removed Referred to as Delta T (ΔT in F ) ΔT – the difference between the intake air and exhaust air Typical ΔT is about 20º - 30ºF

– Air flow, no matter how much, cannot cool below ambient! Fans and Heat Exchangers can never cool below ambient

WATT’s = .316 x CFM x ΔT

Delta T (Tout-Tin)

• Temperature {Delta T or ΔT in °F }– The greater the temperature

difference the more heat removed– Referred to as Delta T (ΔT in °F )– ΔT – the difference between the

intake air and exhaust air Tout – Tin (In F)

– Air flow, no matter how much, cannot cool below ambient!

Watts = .316 x CFM x ΔTOr

CFM =Watts / (.316 x ΔT)Or

ΔT = Watts / (.316 x CFM)

Charting {Watts = .316 x CFM x ΔT}Watts = .316 x CFM x DeltaT

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• CFM=.(___Watts Heat)/( ΔT or (Tin-Tout) x .316)• [3500 Watts / (20F ΔT x .316)]= 554 CFM

Trade – Off’s

• CFM– Noise – Higher the CFM the more acoustic noise

Direct relationship between CFM and acoustic noise Big problem in residential areas – at night particularly

– Power usage – The higher the CFM the more power consumed Money, availability, efficiency, etc

• ΔT (Delta T in F)– Avoid high ΔT (Stay between 20 – 30 F ΔT)

Why – Thermal shock, expansion and dew point Always keep internal temperatures of cabinets above Dew

pointCondensation issues (Mold, corrosion, water droplets, etc)

The higher the CFM or ΔT the higher the heat dissipation!

Watt’s > BTU’s > Tons

– 1 Watt = 3.413 BTU’s (BTU/Hr) 5,000 Watts = 17,065 BTU’s

– 1 Ton (refrigeration) = 12,000 BTU’s 5 Tons (refrigeration) = 60,000 BTU’s

– 1 Ton (refrigeration) = 3,516 Watts 5 Tons (refrigeration) = 60,000 BTU’s = 17,580

WattsTypical Home AC unit

In Midwest will have 2 to 4 TON AC unit

7,000 to 14,000 watts

Typical Home Electric Range240Vac x 30 Amps

7,000 watts

Equipment Data Form(Thermal Evaluation)

• Considerations to include in thermal evaluation: – Size H x W X D (Surface area)– Outdoor maximum temperature– Maximum allowable internal

temperature– Internal heat generation– Cabinet color– Environmental Rating

Select a cooling system that will maintain rating

– Added insulation R-0, R-2, R-4,R-6– Solar shielding

Thermal Sizing SoftwareCalculate cooling requirement, select color and insulation

Use free software toassist in calculations?

Understanding Types of Cooling• Open Loop: utilizes the ambient or outside air,

filtered or unfiltered, to cool the electronics. – Can be outdoor rated UL/CSA/NEMA Type 3R

• Closed Loop: maintains the sealed integrity of the cabinet while utilizing the internal cabinet air to cool the electronics

– Maintains sealed environment rating UL/CSA/NEMA Type 4 or Type 4X

– Air conditioner Can provide internal temp below ambient

– Heat exchanger (air to air) Internal temp is always greater than external

• Passive Cooling: cooling occurs via natural convection and heat dissipation

• Hybrid: systems that utilize both air conditioning and a open loop ventilation to reduce annual energy costs

Closed Loop Cooling

Open Loop Cooling

Insulation – Improving R Value• Adding insulation to the

inside of the cabinet:– Reduces the external

solar and ambient temperature impact

– Reduces the ability of the cabinet to radiate an internal heat load

– Usually results in using a AC unit

– Balance solar shielding to insulation Foil Back 1”

foam insulation

Thermal Options• Fan w/o Filter

– Open Loop– Clean Air– Ambient

temperature below 95F

– Economical– Need to gasket?– UL Type 1 or 3R

Cabinet– For filtered air

use UL Type 12 or 4 (Gasketed)

– $

• Heat Exchanger– Closed Loop– Dirty air– Ambient

temperature below 90F to 115F

– Does not address humidity

– Fully gasketed cabinet

– UL Type 4, 4x, 12– $$$

• Air Conditioner– Closed Loop– Dirty Air– Removes humidity– Ambient

temperature above 90F (Up to 130F)

– Fully gasketed cabinet

– UL Type 4, 4x, 12– $$$$

Hardened Vs Standard Equipment!!!!

Hybrid Economizer• Combination of an Air

Conditioner and Direct Air Cooling– Open Loop when outside

air is drawn into the cabinet

– At Night cool air is drawn into the cabinet and heat is dissipated

– During the day the AC engages – Closed Loop

– At night – much quieter no compressor

• Fast Payback years– Saves money by using

less power in total

OSP- Calculating Thermal Load

Internal equipment Load

Conduction thru cabinet walls ΔT extremes

Solar Load

Total Cooling Required

+

+Sun

Power

Ambient temperature

OSP- Calculating Thermal LoadTotal Thermal Load =• Internal power used

– Measure or calculate power– Voltage x Amperage = Power

(Watts)• Ambient temperature

– Max expected surrounding temperature

• Solar load (Add to equation)– Surface area exposed

97 watts / ft² (Typical for USA)– Finish (White color is the best)– Reflection – Buildings, roads, etc

Use free software toassist in calculations?

Sun

Power

Ambient temperature

Watts + (.37 x Area(FT²) x ΔT) + Exposed area to sun (3 sides) = Watts Cooling Needed

Solar analysis- Exterior Paint FinishWind

Temperature

Solarintensity

Exteriorfinishes

MaterialsSteel, Stainless Steel, Aluminum

Fiberglass

Temperature Rise - Color InfluenceInternal Enclosure Temperature above

Outside Ambient Air

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AluminumANSI 61StainlessRAL 7035BlackWhiteFiberglass

Clouds moved in andwind speed increased

June Solar Data from ASHRAE Handbook

June Time of Day Solar Irradiance and Solar Heat Gain Factors (ASHRAE) for Latitudes 32°North and 48°North

(Note: Clearness Number=1; Ground Reflectance=0.20)

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4:00 AM 8:00 AM 12:00 PM 4:00 PM 8:00 PMTime of Day

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Horizontal Surface Lat. 32°

Horizontal Surface Lat. 48°

Direct Normal Solar Irradiance Lat. 32°

Direct Normal Solar Irradiance Lat. 48°

US - Canada Border Vs US – Mexico Border

Top Solar Shield• Provides added ingress

protection• Drip edge• Reduces solar load by

25%• Protects gasket from UV• Potential downsize

thermal solution• Reduces cooling power

needs – less cost to operate

Test with Solar Shields

• Test to compare temperature rise

– Top shield only– Top and side shield– One set of data run with

internal heaters

Results of Top Solar Shield

• Shielding provided no measurable resistance for internal load (Internal heat load was not impede dissipation!)

• Top shield only provided a 5°F drop or 25% Reduction• Combination Top and Side shielding provided a 10°F drop

or a 50% Reduction in Rise due to solar shields

Thermal Summary

• Sizing thermal cooling impact of:– Color– Shielding– Insulation

• Feature cost-benefit energy consumption– Cost to insulate Vs cost to air condition

Understanding Thermal Requirements to Avoid Extra Cost and to Run “Greener”

Valuable Thermal Tools• Non-contact thermometer

– Measures surface temperature– Indirectly measure air temperature

• Amp meter (clamp on)– Measure current flow– Power in = Heat out

• PDUs with Amp meters– Provides current flow

• Anemometer– Measures airflow

• Calculator– WATTs = .316 x CFM x ΔT

Power Strip with Meter

Summary• Life Cycle

– Identify internal temperature for optimal Life and Reliability• Insulation

– Insulate when the max allowable internal temp is below the maximum ambient

– Cost approx vs reduced size air-conditioner or thermal electric saved and reduced annual consumption

• Insulation– In most cases do not insulate when internal temp is above

ambient• Color

– Use white when acceptable– Color Cost Usually Zero $, reduced solar load by 100 watts

on the insulated cabinet and by 300 Watts on the non insulated, down sized heat exchanger (less cost)

• Solar shield– Top shield reduces load by 25% has a 4 year payback

Thank YouBrian Mordick, RCDDProduct ManagerHoffman EnclosuresAnoka, MN763-422-2168Brian.mordick@pentair.com