AC and DC Drives: Drive HeatDissipation and EnclosureSizingThis is an upgrade of the Application Notes Binder Article 1B. ThisApplication SolutionTable 2. SP200 Drive Dissipation*upgrade reflects the latest product offerings from Reliance ElectricStandard Drives.HP100115 VIntroductionAC and DC drives are very efficient devices. AC drive efficiencies1Even with these high conversion efficiencies, drive losses (heat200240 V200240 V1 phase3 phase3 phase/2303030301525211 /2808047-50-2-908585are 95%, while DC drive conversion efficiency is often over98%.200240 V* Assumes 8 kHz carrier frequency (worst case)dissipation) must be considered when sizing the enclosure thatwill house one or more AC or DC drivesIn this application note, we will provide AC and DC drives wattsTable 3. SP500 Drive Heat DissipationHPpurposes.Drive Heat Dissipation1/4 -1575 V70605090200240 V80losses and the standard enclosure heat dissipation capabilities.This provides for an appropriate cabinet selection for installation380460 V115 V2-1201003-2101401205-250180180Because AC and DC drives operate at less than 100% efficiency,127/--210220heat is generated by the drive and expressed in terms of watts10--250-loss. Tables 1 through 6 provide values for a wide range of AC and15--375--600-DC drives.Table 1. SP120 Drive Heat Dissipation*20-

Table 4. NEMA GV3000/SE Drive Heat DissipationHPTable 4a. Bookshelf GV3000/SEDrive Heat 014031ET4060518018038ER40607 4160HP115 VAC230 VAC115 VAC230 300-5100350-6150400-7350* V/Hz models only** Chassis style units*** Derikon model onlyModel No.Watts Loss6070100150210250380470600Table 5. Single Phase DC Drive Heat Dissipation(Watts Loss)Minpak Plus/Flexpak Plus1/31/23/4111/2235DC3 60 Watts at full load (all models)DC2

Table 6. Three Phase DC Drive Heat Dissipation(Watts Loss)face area of the cabinet becomes the determining factor in sizingtotally-enclosed cabinets for heat dissipation. Horizontal surfacesdo not dissipate heat well and therefore are not considered as afactor. Since the back of the cabinet is usually against a wall,heat dissipation from this area should not be considered either.The resulting calculation can be based on the front and two sidesof the cabinet as long as there is at least six inches of unrestricted air space between the cabinet and adjacent structures. If acabinet side is against a wall, then that side cannot be considered in the heat dissipation calculation.An internal circulating air increases the amount of heat transferred to the walls of the cabinet and hence to the outside air.Instructions for sizing Cabinets1. Locate the watts loss value for the type of drive being usedand its horsepower rating from tables 1-6.2. Based on the type of enclosure required for the application,locate the minimum enclosure size from table 7 that will dissipatethe watts loss of the drive selected in step 1. (Note that NEMA 1is vented enclosure whereas NEMA 3, 3R, 4, 4X, and 12 are notvented.)13. Ensure that the selected enclosure is large enough to housenot only the drive (with adequate clearance for air ventilation perChoosing An Appropriate Cabinetassociated instruction manual) but also any additional controlThe data in table 7 provides the heat dissipating capabilities foritems that may require cabinet mounting. Examples of additionalall standard wall and floor-mounted cabinets.items are input-line fuses, circuit breakers, contactors, relays,timers, etc. Table 9 shows watts loss values for these items.NEMA 1 vs Totally-Enclosed Cabinet Heat DissipationNEMA 1 cabinets (with louvered or slotted openings) have consid-These additional devices can result in sizing a larger enclosuredepending on the required mounting space.erably more heat dissipating capabilities than totally enclosedtypes. In NEMA 1 enclosures, hot air rises with the cabinet, drawing cooler air in through the openings in the lower sections andexhausting hot air from the openings at the cabinet's top. Totallyenclosed cabinets must count primarily on radiation and conduction as their means of dissipating heat and therefore must besized based on their conduction and radiation capacities.A cabinet will dissipate most of its heat through exposed verticalsurfaces due to convection air currents; therefore the vertical sur-1Fora further discussion of NEMA and its definitions, see "Doesthis Nema Rating Match Your Required IP Rating?" (D-7745)

Table 7. Enclosure Heat Dissipation CapacityHxWxD(inches)CabinetTypeVerticalsq. in.WATTS NEMA 1WATTS NEMA 12WATTSPositivepressureNo. P.U. fanP.U. FanP.U. FanOnlyP.U. 0575600NA86x34x241-bay floor-mount7,0391,6202,1207608804,14186x64x242-bay -bay floor-mount12,2442,8403,7601,2301,41012,000P.U. Power UnitApplications with Multiple Drivesof the sides, front of the enclosure. Again, since the assumptionFor multiple drives in one cabinet, add the watts loss values of allis that the cabinet sits against a wall, the back area cannot bedrives to obtain the total watts loss that the enclosure will beused to dissipate heat.required to dissipate. Use this value for steps 2 and 3 above.Other Cabinet and Heat-Related IssuesType "1A" and other Enclosure DefinitionsSlots and louvers provide ventilation in NEMA 1enclosures. TypeThen, apply this formula for a close estimation of the watts dissipation:Watts dissipation 0.125 (watts/in2) X Vertical sq. in."1A" is not defined by NEMA and carries different meanings toCheck the value calculated against the watts loss of all drivesdifferent people. Some people believe that "1A" means a pressur-and accessories to be mounted in the cabinet to see if the size isized cabinet, while others believe that it means door gaskets aresufficient.added to a NEMA 1 cabinet. Pressurized cabinets are sometimesconsidered to be dust-tight as the positive pressure prevents theDe-rating for High Ambient Conditionsingress of airborne particles. The definition of "1A" varies fromThe watts loss values provided in the tables above and the formu-customer to customer, so get a clear definition from them beforela are based on a 40 C ambient and allow for a 15 C rise to 55 Cspecifying NEMA "1A".(internal). If the application conditions require the enclosureSizing Cabinets Purchased ExternallyReliance Electric Standard Drives provides NEMA 1 and NEMA 12cabinets as per the selections shown in the D-406 catalog.However, there are requirements for other cabinet types such asNEMA 3, 3R, 3S, 4, 4X, and 13 which must be externally purchased through a third party. To establish heat dissipation capacities for these cabinets, determine the total vertical square inchesmounted in an area where the ambient exceeds 40 C, table 8should be used to de-rate cabinet heat dissipation capability.

Table 8. High Ambient De-rating factorsAmbientTemperatureDe-Rating FactorooCabinet Heat Capacity X 1ooCabinet Heat Capacity X .602ooCabinet Heat Capacity X .253ooUse seperate ventilation40 C (104 F)45 C (113 F)50 C (122 F)55 C (131 F)De-Rating for High Ambient ConditionsThe watts loss values provided in the tables above and the formula are based on a 40 C ambient and allow for a 15 C rise to 55 C(internal). If the application conditions require the enclosuremounted in an area where the ambiet exceeds 40 C, Table 8should be used to de-rate cabinet heat dissipation capability.De-Rating for High AltitudeAltitude is also a factor in enclosure heat dissipation capability.All heat dissipation capacities in the tables are based on an altitude of 3300 feet (1000 meters) or less. At higher altitudes, airdensity, fan efficiencies, and heat transfer efficiencies alldecrease. De-rate heat dissipation capacity of the enclosure by3% for each additional 1000 feet (305 meters) above the 3300feet (1000 meters).Air ConditioningAn alternative to relying on heat dissipation solely through radiation and conduction in totally enclosed cabinets is to cool thecabinet via air conditioning. Since air conditioners are rated interms of BTU/HR., controller watts loss must be converted toBTU/Hr as follows:BTU/HR Watts X 3.413Please note that not all drives cabinets can be air-conditioned norare all air conditioners UL -listed. Please contact RelianceElectric Drives group for application assistance when consideringthe use of air conditioning.

Table 9. Component Heat Loss ValuesNOTE: This material is not intended to provide operational instructions. Appropriate RelianceElectric Drives instruction manuals precautions should be studied prior to installation,operation, or maintenance of equipment.Reach us now at www.rockwellautomation.comWherever you need us, Rockwell Automation brings together leadingbrands in industrial automation including Allen-Bradley controls,Reliance Electric power transmission products, Dodge mechanical powertransmission components, and Rockwell Software. Rockwell Automation’sunique, flexible approach to helping customers achieve a competitiveadvantage is supported by thousands of authorized partners, distributorsand system integrators around the world.Americas Headquarters, 1201 South Second Street, Milwaukee, WI 53204, USA, Tel: (1) 414 382-2000, Fax: (1) 414 382 4444European Headquarters SA/NV, avenue Herrmann Debroux, 46, 1160 Brussels, Belgium, Tel: (32) 2 663 06 00, Fax: (32) 2 663 06 40Asia Pacific Headquarters, 27/F Citicorp Centre, 18 Whitfield Road, Causeway Bay, Hong Kong, Tel: (852) 2887 4788, Fax: (852) 2508 1846Reliance Electric Standard Drives Business, 24800 Tungsten Road, Cleveland, OH 44117, USA, Tel: (1) 888 374 8370, Fax: (216) 266 7095Publication D-7752 – May 2000 2000 Rockwell International Corporation All Rights Reserved Printed in USA

U.S. Drives Technical SupportTel: (1) 262.512.8176, Fax: (1) 262.512.2222, Email: [email protected], Online: not belonging to Rockwell Automation are property of their respective companies.Publication D-7752 – May 2000Copyright 2000 Rockwell Automation, Inc. All Rights Reserved. Printed in USA.