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I. Iv. . III -leI .li: who . r I - I... I I III. . I . . I I a $0.240 0.. o . . j I . .1 I . .I I I I v I . I I II . I . II I I I u I I . i . _ . ... I f ...I III .... .. Liv-.9 . I r I. I -. Lu. .0 II II . I I .... I . I. . _I .I r- , I I I I II. n. I ..I. II -J.- I I IN. a m MILL! women rm coom now: AND 11's PRACTICAL APPLICATION IN ”CIDER! IIIDUSTRY. mun for host“ of I. B. John Damn-d 20.311: 1931 THEME IITBCDUCTIOI In prepsring this thesis, considersble intornstien. illus~ trstions end dets hsve been secured from vsrioue sources. The generous response reoeived from sll of the motor unui’eoturers who were spproeched while securing this neteriel prompts the suthor to express his sppreoistion here for the sssistenoe "M.r.de The obJeotive of this study being to determine the extent to which this perticuler type of motor my be economicully epplied, without ettenpting to determine the perticuler nuke of motor that might be considered best, the author hes purposely refrained from using any nsnui'scturer's me or any nteriel which could be easily identified. It is understood, theretore, thet my enterisl embodied herein hes been used only for the purpose of illustretion or proof end not beoeuse of my prefer- ence or opinion the suthor night hsve i’or eny psrtiouler testnre of construction. 1. mm 01' TH! nmmnc comm ROM since the phuemene celled electricity res first discovered. men heve been etteepting to develop nes seys of using it to lighten the burdens of humenity. i'o ettempt to enumerete ell of the meny weys in tioh this boon to menkind hes been utilised to eid in eetiefying the sunts of mu could be e stupendous test end one shioh would not edd much‘ to the velue of this investigetion. In order to prepere the proper beckground or besis for this perticuler study, it will be necessery to ettenpt to treoe et leest e por- tion of the developments in one epplicetion of this interesting egent or force. In ettempting to treoe these developments, may confusing reports heve been received from different sources. For this reeson. eny seeming discrepenoy in stetements mede herein will kindly be overlooked since the purpose of this study is not to prove when eny perticuler developeent took pleoe but rether to determine how one specific fore or type w best be epplied te nodern industry end to whet extent it my profitebly be used. Ihe title es previously given, infers thet this study concerns the preeticel epplicetion of the totelly enclosed fun cooled notor. In order to more cleerly stete the purpose of this investigetion, it my be seid thet the ultimete obJective is to determine not only the precticel eppli- cetion of this type of motor, but to esoertein the eoonomicel limit to which industriel menegenent ney go in investing in this type of equipment since it is en obvious fect thet the first cost of this motor is greeter then thet of the more femilier end populer open motor. Ihet is now celled, in the verneculer of the profession. the open notor, tee. of course, the type first developed in the process of epplying electricity to the doing of len'e vork. leny houre heve been spent in studying how to improve it end much eoney hes been spent in experieenting with different idees or theories which were edveneed by thoee interested in its development. is the motor reeched the stege in its development where it wee reelly precticel to use in doing work, other problems were encountered which greetly vexed those vho were mehing use of it. The problems which - hed been encountered up to this time were either principelly mechenicel er electricel. we difficulty, however, wes encountered which wee closely releted to both the electricel feetures end the mechenicel elements of the motor. rhis wes the neceesity for providing protection for the vulnereble end eesily demeged perts of the motor when used in oertein pleces or for oertein perticuler purposes. Ehere were my different schemes devised for providing protection, nost of which were limited in the emount of protection provided. To meke the description of these different types es brief end cleer es poseible, the following definitions heve been teken from the letionel llectricel 2. lanufacturers desccietion Publication Number 30-2 issued in October 1930. Ihese definitions. as fer as poseible, will be given in the order in which they sere finally adopted as standards end not as they were first conceived. 1e OPCnJ'IBhIHCe in open machine is a machine of either the pedestal bearing or end bracket type, with no restriction to ventilation other then that impoeed by good mechanical construction. 2. semi-Inclosed llaohine. a semi-enclosed machine is a machine in which the ventilating openings in the frame are protected with wire screen, expanded metal, or perforated covere, the openings in which muet not exceed 1‘ sq. in. in area and must be of such shape as not to permit the passage of a rod larger than & inch in di‘ICtCre lxception - Ihere the distance of live parts from the guard is more than 4 in. the openings may be 3} eq. in. in area, but must be of such shape as not to permit the passage of a rod larger then f in. in diameter. 3e IO‘CII’ IDBIOICQ H‘Oh1n.e en enclosed machine is a machine tion is so completely enclosed by integral or auxiliary covers as to practically prevent the circulation of air through its interior. such a machine is not necessarily air tight. .4. Protected llachine. d protected nachine is a machine in which the armature. field coils and other live parts are protected mechanically from accidental or care- lese contact, while free ventilation is not materially obstructed. 5. Separately Ventilated liachine. l separately ventilated machine is a machine adapted for connection with means external to the motor for passing air through it. 6. Incloeed Self-Ventilated llachine. (a) An enclosed self-ventilated machine is a totally enclosed machine except that openings are provided for the admission and discharge of the cooling air, which is circulated by means integral with the machine. These openings are so errenged that inlet and outlet duct pipes may be connected to them. (b) Ihen inlet or outlet ducts or pipee or both are used to conduct air to or from an enclosed self-ventilated machine, they shall be so arranged and have ample section to furnish the epecified volume of air to fit. mn.e 7. Inclosed separately Ventilated lachine. (a) An enclosed separately ventilated machine is a totally enclosed machine, except that openings are provided for the admission and dis- charge of the cooling air, which is circulated by means external to and not a part of the machine. The" openings are so arranged that inlet and outlet duct pipes may be connected to then. (b) 'rhe external fan or blower furnishing air to an enclosed separately ventilated machine, together with the inlet or eutlet ducts er pipes shall be of such capacity and so arranged as to furnid the epecified volume of air to the machine. 3. d. rotally lnolosed l‘an Cooled Mine. A totally enclosed fan cooled machine is an enclosed machine equipped for exterior ventilation by means of a fan or fans, integral with the machine but external to the enclosing parts. As previously stated. it has been found difficult to secure authentic information regarding the sequence of the development of the different types as defined in the foregoing items. Using the information secured and by making a few assumptions ( which lay not be absolutely correct) the following order of development has been arrived at. he open motor as defined under Item 1 was of course the starting point. It has advanced far in its development from the crude form in which it was first built end has now reached a stage of efficiency and refinement which no other comparable form or type of prime mover has, due principally to the ease with which it may be adapted to suit varying con- ditions. me next step or stage of development seems to have been the "protected" machine. In this type of motor the live parts were protected mechanically. from injury due to accidental causes or careless handling of objects or things which might come in contact with the motor. lrhis wgs perhaps the first recognition of the fact that outside agencies or con- ditions could have a very definite effect on the functioning of the motor. At least it leads to the belief that experience had proveu that the frame, end bells and bearing supports were insufficient protection for the vital parts of the motor. . Ihe semi-enclosed machine is but another form of definition of the W just mentioned, although the standard description of this specific form seems to have been adopted previous to that of what is called the “protected eachine." the use of the semi-enclosure was of course an attempt to secure protection for the live parts of the motor. lo definite action seems to have been taken to exclude smaller objects or particles of foreign material from the motor until some time later when the totally enclosed machine was brought out. Ihis development was the result of experience with motors Mch had been operating in atmospheres laden with injurious dust, fumes. etc., which seriously affected the performance of the motor and, in new cases. caused the motor to fail entirely. This type of motor, except in the very seall sises. proved to be very expensive to build, principally because of the difficulty encountered in dissipating the heat generated within the motor. This, together with other mechanical and electrical defects. forced the motor manufacturers to devise some more practical means of providing the necessary protection to the motor. [my schemes were de- vised end tried out with this objective in view, some of which were adopted and etendardised by certain manufacturers as evidenced by the descriptions given in Items 5, 6 and 7. The enclosed self-ventilated machine provided means integral with the motor for circulating the necessary cooling air through the motor but did not prevent this air frca coming in contact with the live parts of the machine. 'i'his. of course, necessitated securing the cooling air from 4. a source which was not contaminated with injurious matter. particles or tunes. I'he expense of this type of construction and installation wee found to be prohibitive in all but the most extreme cases. be enclosed separately ventilated motor was but a variation of the enclosed self-ventilated motor in that the cooling air must be brought to the machine frms a suitable outside source by some means ex- ternal to the motor itself. his method was found to be more expensive and more productive of operating troubles than the self-ventilated motor and was therefore used only in the most extreme cases. None of the may schemes devised up to this time were very successful and continued attempts were made to improve the existing methods or to devise new ones. !he next important step or development was the production of the totally-enclosed fan cooled machine, in which the live parts of the motor were entirely enclosed, the cooling air being supplied and circulated by a fan or fans integral with the motor but outside of the enclosure. This type of motor, after mch research and experimental work, was finally found to be a solution to the problem from the performance standpoint and mch less expensive to build than any of the other types. The motor manufacturers, having arrived at what they considered a practical solution of the vexing difficulties which had been confronting them, then devoted their energies toward improving and refining the construction of the motor. the improvements which have been incorporated in this type of motor in the last four years have been very numerous and important. The discussion of this type of motor which follows is based on motors having the latest im- provements and considered to be among the best available. II. CGIPARISOH O? TOIALL! Home!» us COOLID MOM vrm STANDARD OPEN xoron A. technical Construction. Before the discussion and comparison of the two upes of motors is actually started, one important fact should be stated in order that echo of the handicaps under which the manufacturers have been laboring in developing the totally Inclosed ran Cooled motors may be more clearly understood. In the past many unsuccessful attempts were made to standardise the principal dimensions of open motors. Due possibly to the lack of proper organisation on the part of those advocating the necessary changes, these attempts were fruitless. some four years ago another attempt was made to bring about the desired result. which was successful. it the present tine each of the motor manufacturers is producing a line of motors which are interchangeable with those of other manufacturers who are members of the lational Electrical Hanufacturers Association. Previous to this momentous change. the individual manufacturers had been attempting to make their line of totally enclosed fan cooled motors as nearly interchangeable with their line of cpen motor. To be con- sistent than, under the new schem, they have been endeavoring to manufac- ture a line of totally enclosed fan cooled motors in the new standardised frame sisee which would be interchangeable with the new line of open motor sisee. In doing so, they have been laboring under space limitations and other serious handicaps which, by one who is familiar with motor construc- tion, will be readily understood. Io simplify this discussion and aid in illustrating the features of construction incorporated in the Totally Bnelosed ran Cooled lotor, the Illustrations numbered 1 to 8 were selected. As previously stated, these illustrations were selected because thq best served the purpose and not because of an actual individual superioriv. mferring to Illustration lo. I. the construction shown here is typical of the features embodied in practically all of the different makes of actors on the market today, especially in the smaller sisee. (Frames 884 to 404 incl.) to secure the proper consideration of 1m. important points, it will be best to discuss each part of the motor separately in comparing it with the open motor. ' rhe frame of this motor is inherently the same as that of the open motor, the air duct openings in the center of the frame , however, are 5. closed by means of sheet metal covers. Those coverings are added for the sole purpose of directing the blast of cooling air across the entire face of the frame as well as across the stator laminations and the radiating surface of the inner enclosure. 'rhe stator construction is the same as that used in the open motor, the various manufacturers using practically the same methods of stator iron assembly, insulation, coil assembly, etc., as in the open motor. 'l'he outer surface of the stator iron is left exposed to the direct action of the cooling air. At each end of the stator, an enclosing shield has been added which forms part of the enclosure around the live parts of the motor. Ihis on- closing shield, which is as thin as possible in order to offer the least hindrance to the quick transfer of heat and still possess the necessary mechanical strength, is very carefully joined to the stator and machined around the outer edge to form a dust tight joint with the end cover. iho end cover ahown in Illustration lo. I is formed from sheet ' steel, of sufficient mechanical strength to withstand all normal usage, flanged at the outer edge to fit over the enclosing shield with the inner surface carefully machined. an. inner edge of the center opening in this shield forms a stationary 'seal with the bearing housing and bearing cap, a vellumoid gasket being added for extra measure to insure a tight jeint. rho remainder of the enclosure is provided by the cartridge type grease-packed ball bearing. this type of bearing has been chosen by practically all of the manufacturers since it lends itself best to the problem in question, that of enclosing the vital parts. it this point we find the only "running seal” in the mole enclosure. It is, of course, impossible to build a motor with no running seals, since the shaft must extend through the enclosure if the motor is to be used for transmitting power. In this type of construction, the labyrinth seals at 3 and 3' are depended on to exclude all injurious foreign matter which might work in around the shaft. fhis form of seal has been found to be most efficacious and least liable to be a source of mechanical trouble. It has also been found that if the labyrinths are long enough, this type of seal will moosofully act as a flame shield as well. he type of enclosure just discussed is not used by all manufac- turers, some of whom make use of the bearing brackets to form the dust tight enclosure as well as to support the bearings. This form of con- struction is shown in Illustration lo. 8. There are, of course, advan- teges and disadvantages in both forms of construction, the matter of preference, however, is a matter for the individual to settle since it is not the objective of this study. It can safely be said however, that, all other things being equal, the form of construction which offers the least chance for the entrance of injurious foreign matter, either tux-ouch poor joints, careless assembling, failure of seals, easily damaged parts or other causes, is the type to be preferred. continuing with the discussion of the constructim shout in Illustration lo. 1, we find that the end brachsts of this motor are used primarily to support the bearings and to preserve the alignment of the rotor in the stator opening. This function is as important in.this type of'motor as it is in any type because of the necessity of maintaining uniformity in the air gap. 0n the pulley end of the motor, it also serves to guide the cooling air nearer to the bearing. This is very desirable, since some difficulty has been experienced by some of the manufacturers due to the tendeney of this bearing to overheat. The the mounted on the rotor shaft at the opposite end from the pulley end is enclosed with a housing wlidh serves a double purpose. It serves to guard the fun from.injury as well as those eho work with the motor. Its prime purpose, however, is to direct the incoming air. The design of this cover and the fan is such that the incoming air is suffi- ciont in.quantity to adequately cool the motor and travels with sufficient velocity through the air passages to prevent, in so far as possible, the depositing of foreign material in the ducts. The design of this fen has been very carefully studied since it requires power to drive it and any added power consumption, of course, tends to lower the efficiency of the motor. The loss incurred by the addition of this fen will be discussed more in detail in connection with the electrical characteristics of the Iatore The rotor of this motor is essentially the same as the rotor of the open motor, the only difference being a slight change in the design of the fhns which are integral with it. In the open motor, the function of these rotor fans was to force the air to circulate around the rotor and out through the openings in the end frames and through the stator air ducts. In this motor, the fins serve to circulate the air from the center of the motor, where the heat naturally would be the greatest, to the radiating wells of the enclosure. Since these fens represent no addition to the motor, they therefore represent no added power consumption. The fans in this instance are made of steel, being welded to the stator end ring. Some of the manufacturers, in the earlier stages of the motor's development, made use of a fun at each end of the motor, leaving off the sheet metal covering over the air ducts through the frame. In this type of construction, the air was drawn in at each end of the motor and passed over the end enclosure and stator iron and out through the frame air ducts at the point marked A. Actual application together with close study of the results obtained have led practically all of the manufecturers to adopt the one fan type of construction as standard. The ultimate objective being to simplify the construction of the motor, provide the correct amount of cooling air, eliminate in so fer as possible the deposit of foreign material in the air ducts and to consume as little power as possible in driving the fan. It has been found that the type of construction shown in Illus- trations lo. I and lo. 2 is satisfectory in the smaller frame sizes, and most manufecturers are now showing in their published lists, motors rated up to 40 H.P., 1200 R.P.ll. in the same frame else as the correspondingly rated open motor. Some also build motors of larger ratings in the same frame sise as the open motor. It is generally recOgnisod, however, that the problem of heat dissipation in the sises above 40 8.9., 1200 B.P.li. needs special consideration.and possibly a different fans of construction. 8. To overcome this obstacle, to complete standardization and inter- ehangoability, some manufacturers have adOpted special construction in their cooling devices. One of these types of special construction is shown in Illustrations lo. 3 and No. 4. In this form, known as the Iossay Type, are embodied the following features which are designed to provide greater radiating surface for the dissipating of the heat generated within the motor: A steel header ring is welded to each end of the stator ring. Iteel tubes extending from one end of the stator to the other are welded into openings in the steel header ring. The rotor has but one fan which is so designed that it causes the air within the enclosure to circulate from the central part of the motor through these steel tubes and back into the enclosure again. The circulation of the inside air through these tubes (inch add to the normal radiating surface) causes the heat generated within the enclosure to be carried away faster by the cooling air which passes over the outer surface of the tubes. It is interesting to note that the flow of the inner air is counter to the flow of the outer cooling air. Illustration lo. 4 shows more clearly the actual appearance of the motor with the tubes incorporated in it. llotors of this or similar types are available in all ratings up to and including 150 8.2. in the National Electrical lianufacturers Association frame sisee. Ihile it is true that practically all of the manufacturers cm furnish totally enclosed fan cooled motors up to 150 H.P. in their old line of frame sisee, they are not interchangeable in all ratings with their own open motor lines and, of course, are not interchangeable with motors built by other manufacturers. It is their ultimate aim, however, to pro- dues a complete line of motors in the lational Electrical llanufacturere Association frame sises which will, of course, be interchangeable with all lational Electrical lanufacturers Association motors of the same rating. Some manufacturers have secured the approval of their complete line of totally enclosed fan cooled motors for use in Class II. installations, defined as follows: Class II. locations are "those in which combustible dust is thrown or likely to be thrown into suspension in the air in sufficient quantities to produce explosive mixtures, or those where it 'is impractical to prevent such combustible dust from collecting in such quantities on or in motors, lamps, or other electrical devices that they are likely to become overheated because normal radiation is prevented." ' Some of the manufacturers have developed a complete line of what are knon as "explosion proof motors," which have been approved for use in Class 1. locations. According to the National Electrical Code - Class I. locations are "those in which flammable volatile liquids, highly flamablo gases, mixtures or other highly flammable substances are made, used, handled or stored in other than their original containers.” In order for a totally enclosed fen cooled motor to be classed as "explosion proof" it met be built to fulfill certain requirements which my be stated as follows: the inner enclosure mist be strong enough to withstand aw ex- plosive pressures to which it is liable to be subjected. It must also be capable of preventing possible ignition within the motor from extending to surrounding vapors. In case of a burnout in the absence of overload pro- tection, the motor must radiate heat fast enough so that the surrounding gas will not ignite spontaneously. 9. Some manufacturers have designed a complete line to meet these requirements separate and distinct from their standard totally enclosed fut cooled motor line. Others, by strengthening their enclosures", en- larging the labyrinth seals, using a non-sparking fan and special outlet box, have succeeded in having their standard line of totally enclosed fan cooled motors approved for this class of locations. The prices, of course, are higher than those of the standard line because of the additional features. Comparison of these prices will be made more in detail later. 4.9 I mm: 9233 Z0 ~=< $250.5 «On ZOU 02w mezwm Pw¥m<0 ................... .. . 9013.39, 1.29 45m 5220:.(5 .5053 ozafim EOE zw>0U 02w 3.1m 92304075 oz< ¢w>OU 02w ng E omZiUg 50:. 9.0 $22.55 oz< 92.30: oz. .53 $38 02m 2338 5.99 9055ij 25, ....mm €20.25 zw>OU 02w Swim ozmbdzu oz< «96.... ozm 2328 E 82.55: Eh: a2 @2308 napoumuo mamom Swamp uhnmfi 6cm mpam omoHo .wnon mmmwmmmoza4 w>HmOAaKW 2H mmb mom moeoz @640 RmmmHDGm no way? .mpoxocan mnaamon_ucm choc noumpn no uaonanm Gamay omnmmm mafia manna Hmapmmpmpnm z_ m3 0 4V z_ aa< wmuaooo no conch» umo copoanunca L3 panama macaw one can cool» FL-» IIIIJ ~:< sop moomnm omamg mowmmmmn ham owama ho, Gnu, hoaam Bondsman wnaxaunnunoz I‘“ omnmoon ooanmmm ma ham wmaaooo Ho cwmmmmn moan # III .332 .830:va 3—000.me come—cg -.a = o9: $38 32> mmomaoomémcao o o m \ = a IA 5: . _ mz..._.Sz_u .:..z~:,r/._ / 4/ . .. \ \ ‘l I I II. “ \ i=2: :5. hie/.2: i=2? 27.4 gummy. 5.5 32.53: ..5 7.3.29. Show .12 c./._M_chcu.e.33.: Keisha: .:_...I .Em.../.c_t..._.m :95: r: :../=.:>.._ 2.3.2: 23.. 37:33; .:..z~:,;m . 52:: .25. $1.}: . , :. . . . ‘ . . . 37.5,; ..5 72,55; :29. ...—w: $4.37.... ...C 127.; z; :14...” A_.._./_.._./C.v : . . . ; . . . . . . . : . ., 7.......E...=_ .77 .E,./c_,_.f_.r. :;_:.5 3.7. z..._:f.___ ,7. 5:; :3... 7.5;... 2.3.2: xx". 145;... ...C $27.: 20.2.: C._../._ 2:24”...— IV mo 1 H08 #V ELECTRIC CORPORATION STANDARDIZED MOTOR MOUNTING DIMENSIONS DIMENSIONS 1N INCHES FRAME :9 25 2: an H u xevwav sf0.PuLLEY 204 5 8 6": 3"6 ”/3: 31 370x33: 3x3x3/4 224 5’2 9 6% 3'/z W32 I dug 4x3'/zx/ 225 5?: q 7V2 3V2 W3; 1 Véfl 4x3’/2x/ £54 W4 10, 5’4: 4’/4'7/32. Na Vflfi 4’/Zx4'/zxu3 , esov: F1502: omaznmmonc ONLY. 254 7 ,1 .qu 43/4 17/3; {V4 1441‘ 75 java/V4 5"15‘EF5‘55IOP5N ml 324 8 w: 1092 5V4 2v}; III; 3mg, @x5V2x/95 C°"‘"°=zz%"%“o&%%8€ was 326 & 12’/Z 12 5% 3V3: (-576 MW. 8x63’4xl‘76 4p SYNCHRONOUS RPM. 64 4 /4 //V4 57/5 2V3: 17/3 ’lzx‘/4 4x74’ix/7/gr ‘ 300011500 1200 400 565 4? (4 IZV4 57/5 21/3; 17/5 ’/Zx‘/4 4x73/4x/7/ Va ; ' 224 404 /0 (6 12% 63’s Il/xc 2V5 ’/Zx’/4/OK71’4xZ’/J 7/4 I 204 225 ~ 405 10 ’6 1:374 037: 0/1. 2% law. Iomuzva ’ F 204 224 234 444 H /a W: m 13m 2% 545m. Maj/4x214; w/zi204 224 225 254 405 u 16 IGVZ 1'72 I3/10: 2% S’xfl/lxwazim 2 3224 4225 254 504 12”: 20 /@ 5V2 We 2/5 find/gram): 25/1 3 ;224: gz5 1; 505 :2’/z 20 16 an 11/14. 27/5 4’4x3/a MIT/3x??? 5 1225 254 “farm: 2: 51mm": .1: 3% 27“.: non-... WZ 1 frames is 2" fund the kcywap is ”2'1: V1: mama NUMBERS FOR LOW VOLTAGE, 00 CYCLE, 5001mm. CAGE M07025 OPEN TYPE. CONT. 40° TOTALLY ENCLOSED, FAN COOLED, CONT. 55.’ SYNCH ONOUS ~ .M- SYNCHRONOU . .M. IZOO (100 O G: 14 O I 00 400 O 000 4 - ZZ 254 224 22 HP. 254 PL‘7 'J: 3'0 UVUV' UV! 04 04 4 4 4 Supersedes .. MF—ZO zoc. Jupcrse ed By 4 84 £6 {VIC—(4802': 10. D. llootrioal Contraction and Charaotoriotico. do prowiouoly montionod, tho construction of tho rotor of tho totally oncloood tan coolod motor io oooontially tho oamo ao that of tho opon motor. tho variouo manufacturoro omploy tho oamo mothodo in aooomhling tho iron.punohingo. rotor baro, ond ringo, and in.koying tho rotor to tho ohaft ao thoy do in tho opon.motor. A oaroful study wao aado or thooo ditforont porto and thoir aooombly in ordor to mako oortain that tho highor oporating tomporaturoo ot'tho totally oncloood tan coolod motor would hawo no ooriouo offocto on tho portormanoo of thio oooontial part of tho motor. Tho otator iron.in tho totally oncloood ton coolod motor io aooomhlod in identically tho oomo mannor as that of tho Opon motor. Somo manufacturoro. haro. howovor, {cund that in ordor to absolutoly ooal tho livo parto of tho motor tho: woro obligod to eliminato tho air duoto which woro tormorly incorporatod in their otatoro. Thio, in oomo inotancoo, hao rooultod in.hottor officiancioo oopooially in oomo of tho langor oizoo of motoro duo to tho incroaood amount of iron.and improvod copper diatri- hution. Tho principloo ommodiod in tho conotruction of tho otator winding have not changod matorially. A tow of tho manufacturoro ooom.to hold tho viow that looo insulation of tho otator winding is nocoooary. hocauoo thooo inJuriouo agonto or torcoo which tormorly cauood oo many insulation failuroo. haoo boon oliminatod'hy tho comploto oncloouro ourrounding tho livo parto of tho motor. iloot of tho manutacturoro otill uoo tho oano ins oulating matorialo and in tho oamo quantitioo ao in tho opon motor. Ban porionco ooomo to ho proving that thio io worth whilo and it io oafo to oay that wory tow of tho manufacturoro will agroo to any natorial roduction of tho amount or quality of tho inoulation uood. Particular attontion hao boon givon.hy moot of tho manufacturoro to tho mannor in which the loado aro brought out from tho otator winding to tho connoction outlot. Tho cponingo through which thooo loado aro brought out of tho oncloouro aro uoually ooalod with a ooni-ooft, non, cracking compound in a mannor oimilar to that ohown in illuotration lo. 8. laporionco with tho oarlior typoo of totally oncloood tan coolod motoro hao ohown that unlooo thooo loado aro woll protootod whoro thqy paoo through tho otator iron and tho air duct, that tho abraoivo action of tho ontrainod duot will ooon cauoo failuro at thio point. Having found that tho olootrical conotruotion of this typo of motor hao‘hoon givon outticiont attontion to inouro propor portbrnanoo, long lifo and production coot comparahlo with that of tho opon.motor. wo thonnmuot prooood to tho im- portant otop of comparing thoir portbrmanoo charaotoriotioo. through tho oourtoay and aooiotanoo or ono of tho prominont motor manufacturoro, portbrmanco curvoo havo hoon proparod from actual toot data ohioh ohowo what can'bo aooompliohod with tho totally oncloood ton coolod motor ao comparod to tho opon.motor portormanco. iho data from which thooo curvoo woro proparod woo takon from tho toot data ooourod.h: tooting a group of motoro in oach of tho opooifiod ratingo. rhooo curvoo woro proparod for oach oioo of.motor in tho 1200 mum. rating tron 1% 3.2. to 30 3.2. no attompt wao m to proparo curvoo for motoro largor than 50 H.P. duo to tho fact that in.induotny 11. today by for tho groator oharo of tho aotoro in uoo aro includod in that rango of oiooo, and to a cortain oxtont to tho lack of availablo data on aotoro of largor oiooo. It may aloo bo oafoly acid that thon tho purchaoo of a motor of thio claoo. in oiooo largcr than 40 H.P. io boing conoidorod, porformanco ourroo ohould bo ouppliod by tho manufacturor and givon ooriouo concidoration by tho purchaoor. Thio otatomont io Juotifiod by tho invootmont involvod, tho amount of powor boing appliod in ono unit and tho rolativoly omall numbor of thio oiao of motoro in uoo in comparioon to tho anchor of tho oaallor oiooo. In making up thooo porfornanco ohooto only tho Rovolutiono pcr linuto or Blip curvoo. tho Bfficicncy curvoo and Powor Factor curvco woro ohown. 'l'ho Amporo and Kilowatt curvoo woro not plottcd oinoo thoy will, of couroo, vary uniformly with tho officioncy. Tho llovolutiono Por Iinuto or Slip curvo io, of couroo, idontical oinco thoro aro no radical difforoncoo in tho dooign of tho two motoro which would cauoo a variation in th. 0111). who powor factor of tho two claoooo of motoro wao found to bo practically idcntioal. Tho apparont olight variationo oncountorod woro undoubtodly duo to variationo in tho individual motoro oinco tho majority woro found to bo aliko. whio point io ono to which tho onallor induotrioo uoually fail to givo propor ccnoidoration. It ohould bo givon ooriouo oonoidoration, howovor, ao tho largor induotrioo particularly thooo oporating undor powor ratoo containing a "powor factor" ponalty clauoo. or thooo having a largo powor notwork, havo loarnod by oxporionoo that it hao a ooriouo offoot on thoir cporating cooto. Tho officioncy curvoo ao 'ohown indicato a lowor cfficionoy for the totally oncloood fan coolod actor, duo, principally, to the added load of tho cooling fan and tho highor operating tomporaturoo. In moot of tho motoro for which tho curvoo woro plottod, tho offioionoy wao found to vary froa i to 2% lowor for tho totally oncloood fan coolod motor. lnopoction of tho curvoo, howovor, ohowo that from it to 1} full load thio variation io from fi to 1%. Invootigation of data oocurod from oomo of tho manu- facturoro concorning tho looooo attributablo to tho fan chow oonc variation duo, without doubt, to tho difforonoo in fan dooign and air duct dooign. rho tablo givon bolow io for ono particular mako of motor and dooo not. of oouroo,apply to all. ' cooling fan Looooo in Iatto 060 1140 1725 homo £11 an m 285 c 15 43 864. 18 24 67 284 23 48 120 524-5 54 63 100 364-4, 404-5 40 90 856 tho forogoing pointo of difforonoo in porformanco will bo givon olcoor ocrutiw in ono of tho following oootiono of thio otudy. MICHIGAN STATE COLLEGE .---O— «- 1 ha on---.--- a a . 1.- r: .... .4 . :5 . ‘r p‘ 9. Q - t o .a’... .- colon-+0 ’. .01 c.o¥v O aloIOoI VH0-.»ai uovocrv fl..." 'I‘.ol‘ .10 0a.. ovaaoYa $.n ’onro L$t17o04 1 ‘HITI - b o 9-.- .44. ago-'oqpvo.. W on 0! 4" a :4 o a o.‘ T It... _ a 0’, ...Jvtorlf - . 1 0 .oOO-ov b—‘v-d I if; ~o DEPARTMENT OF MATHE o MICHIGAN STATE COLLEGE '11.. 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Ar .. . .ry. .4ufi? m ... l - O M'yvka 5v . a . . .. .| .1 1 H1 . . .Lfl. F I .t’ 0‘ .~ 0 I . .7 I a . ' . . o ' .W‘f“ 1.... ..— n . o I .,. ', ’0 c "O O r 9 . ; ‘ . 09-04 v b-n O . ¢. 9 y‘Q—b ov°Y+ MICHIGAN STATE 'COLLEGE v ..A. y. 0'.— 01 ' \ .... ...... 0-y- -.....roo 1...‘ —l ...1 .. Q . , ‘..<,-..,. .-.V ., ~- . .4 L . 1T;L '7 Oltxt‘. .O'PA - 9‘4 ~~yo->- -->- O" o b 9 v . 5 o ‘ . Q togyuyys. ¢ho¢ . o 5~‘-oco1 ......94' 1 \IO 1.1! t +1. ...debov a .9..l‘. .. . . . v9 '11 o+< .. . . n .I" € . .2 . DEPARTM EN f OF MATH EMATIC. MICHIGAN STATE COLLEGE 6 . o 6 v-c -... Hiv- yt>4~476 .$. ..fioi», -+ uJ- otllg.ro-¢ pvqoonu q 0 O. 4 I ‘0 o._4‘o‘_s-. tll Ihrll . . orb '79 ~90. v\--. ‘- Ho-J’—‘pc ~4-‘ v-f¢o£>b . . ...If ¢+. vOPP 54 r ¢~a q» . L PARTMENT OF MATHEMATICS y . .:- 12. III. APPLICATION OF TOPALLY EHCLOSED rm coom MOTORS IN MODERN INDUSTRY its much discussed problem of "Group Drive" versus "Individual Zlotor Drive" is still a live issue with some industrial engineers. The tendency however, in the majority of cases, seems to be in.favor of the "Individual motor Drive." The arguments pro and con.are many and varied and need not be discussed here except to note that with the motor mounted on or near the machine, the motor is in many cases subjected to more of the injurious effects of the dust and dirt, fumes, etc., caused by the operation of the equipment or by nearby machines or processes. Ehis fact has, of course, a decided effect on the recognition given to the necessity of providing protection for the motor. Ehe most successful maintenance engineers in industry today are those who believe in, and make use of the theony that the best way to handleilnintenanoe is to prevent it. Briefly, maintenance problems cease to be problems if they are anticipated and prevented. In order, there- fore, to keep out of trouble, the maintenance engineer seeks to prevent it. mhe totally enclosed fan cooled motor in.its present form.has proven to be one of the most efficient trouble preventers the maintenance engineer has been able to find. It can be operated in atmospheres laden with dust and dirt so thick that the ordinary cpen motor would cease to function in less than an hours time if exposed to it, because the dust and dirt are absolutely prevented from coming in contact with the live parts of the motor. It is therefore well suited for application in the metal working industries, foundries. salmills, glass factories, cement mills, steel mills, grinding end finishing rooms and various other applications. It is especially applicable in locations where explosive dust is in suspension in the surrounding air. This dust is usually not explosive except when in suspension in the air and requires a spark or flame to ignite it. who motor being built to exclude dust and dirt, rarely fails and if that should happen, the spark or flame would be smothered by the tight enclosure. The motor can therefore be used to good advantage in coal and coke handling plants, sugar mills, fuel pulverisers, flour and feed mills end grain elevators. Corrosive gases or fumes in the air which passes through an open notor have a serious effect on the insulation of the windings and in some cases attack the shaft, bearings and rotor. The totally enclosed fen cooled motor in reality is not a fume or vapor proof motor, but allows such a small amount of these injurious agents to reach the live parts of the motor that their inJuricus effect is negligible. It is therefore applicable in most instances in.dyeing and cleaning plants, plating and dipping rooms, chemical plants and the paint and lacquer industries. 13. in open motor operating in the presence of steam, moisture, oil spray, cutting and grinding compounds is usually short-lived because of the injurious effects of these agents on the windings and bearings. The totally enclosed fan cooled motor Operating under the same conditions suffers no injurious effects if its design is such that the live parts are really totally enclosed. Ileny applications of this nature are found in ice plants, dairies, laundries, paper mills, pulp factories, oondenseries, building trades, pump installations, power houses, packing houses and canning plants. Ihile making this study many instances of actual applications were found in which this type of motor had proved very conclusively that it successfully eliminated the disadvantages and handicaps under which the open motor is forced to operate in the classes of locations mentioned above. In some of the instances the totally enclosed fen cooled motor had been operating for more than two years with no attention except for greasing twice yearly. These same motors when opened for inspection were found to be entirely free from dust, dirt, moisture or other injurious matter inside the enclosure. In one specific instance a 7i H.P. open motor had been in use, driving a lathe. IThe material being worked on was cast iron. Due to the excessive amount of fine cast iron dust in suspension in the air and to the amount which actually fell directly upon the motor, it had been ex- ceedingly difficult to keep the motor running. In fact the motor had been rewound at least once in the year preceding the change in spite of constant daily attention. The open motor, when removed, was in such a serious con- dition that it had been showing signs of overheating for some time. a 6 LP. totally enclosed fen cooled motor was substituted for the 7} H.P. open motor and has been in continuous Operation for practically two and one-half years with no attention except for what cleaning on the outside which it received when the machine and the surrounding floor was cleared of the accumulation of cuttings and oil drippings. It was greased twice yearly as is the practice with all ballbearing motors. This motor was opened for inspection after 15 months service and again after 11 months service and found to be as clean and free from dust inside the enclosure as it was the day it was installed. The outer air passages, due to proper design, were not clogged or obstructed by the dust and dirt. In another instance a 25 H.P. totally enclosed fan cooled motor was installed on a large milling machine in place of a 25 LP. open motor. In the six months preceding the change the open motor had failed twice and had to be rewound due to shorted coils. In this case the motor was mounted above the machine and therefore was not in as exposed a position as the smaller motor Just mentioned. This motor has been operating for fully two years with no attention except for greasing. lunerous instances could be cited of totally enclosed fen cooled motors which have been in continuous service for periods ranging from one to two years during which time they have been subjected to caustic solution spray, cutting oil and compound mixed with metal dust and cuttings, acid fumes, lacquer thinners and solvents. In some of these instances it has been found difficult to find am kind of paint which will stand up for six months time when applied to the buildings and equipment in the localities 14. in which these actors are operating, due to the action of the acid fumes, and caustic solutions employed in the processes. If time and space permitted volumes could be written concerning actual applications of the totally enclosed fan cooled motor and the results obtained. for those who are, we might say, skeptical, the "proof of the pudding is in the eating," and the surest way to prove to them that what has been said concerning the totally enclosed fan cooled motor and its success is for them to prove it themselves by actually applying the motor on some of their own troublesome applications. 15. IT. CMPABIBOH OF cocrs The ultimate cost to the consumer of any article which he may purchase, whether it be an automobile, a house to live in, a pair of shoes, or as in the case of the question at hand, an electric motor, may be di- vided into four major parts. 1. Initial cost. 3. Cost of operation. 0. Maintenance costs. D. Length of service. The initial cost is the total amount in dollars and cents which the consumer has to pay to purchase the article and place it in service. In the case of an electric motor the installation cost varies with each application as a general thing, and need not be considered in this study except to note that this part of the initial cost will be the same for both types of motors in any specific case. The remainder of the initial cost which we will have to consider is made up only of the actual price paid for the motor. This amount varies according to the discount which the purchaser is allowed. since this discount varies with the individual customer, it will be disregarded in this study, but of course, should be considered by the individual purchaser when comparing the two types of motors as to ultimate .OUte To more graphically illustrate the difference in initial cost of the two types of motors the accompanying sheet of initial cost data (Page ) has been .prepared. The figures shown apply to actors rated at 1200 mm. since that rating is the same as that for which the accompanying performance curves were prepared. he figures for the other speed ratings, however, show the same proportionate difference. is has been previously stated, this study of costs has been con- fined more specifically to those motors rated at 50 H.P. and lower because the great majority of motor applications is found to be included in this range of- sises and because the amount of initial outlay in the sisee above warrants close scrutiny of each application. Inspection of the initial cost data sheet indicates, judging by the variation in price difference, that there is neither "rhyme nor reason" involved in the method used by the manufacturer in determining the price of the totally enclosed fan cooled motor. It is true, however, that production difficulties encountered in some of the frame sises because of space limitations, copper distribution, etc., can be blamed for the apparent erratic variations. The greatest price difference in this group occurs, of course, in the 30 H.P. sise being 65.5%. The average difference over the entire group was found to be 52.5%. In the sisee 1.5 to 10 Rd. inclusive, which constitute the greater percentage of installations of motors in the entire group, the average price difference was found to be 16. 41.2%. The average price difference in the sises 15 H.P. to 30 H.P. inclusive is found to be 52.5%. The average difference over the entire group being 45.7%. The average price differences shown should serve only as a guide in.arriving at a decision as to which type of'motor to use when install- ations of motors in groups, where the sises will be representative of the group included in this study, are being considered. it first glance the price differences shown would indicate that the totally enclosed fan cooled motor is handicapped to quite an extent by its first cost. further study of the problem, however, shows that although the price difference seems out of prOportion to the additional material and labor needed in producing the totally enclosed fan cooled motor, the additional advantage of lowered maintenance costs, longer life, and elimination of interruptions to service will offset it. The management of any industry usually sets a definite time limit in which any investment is expected to pay out. This period varies in different organisations and different classes of industry. For the problem at hand, it seems fair to select a three year period since this conforms to the practice of the majority. 3y inspection of the cost data sheet we find that the 7‘} LP. and the 30 HtP. sises show the greatest price difference. It seems logical, therefore, to select two sises as examples for investigation. Due to the lack of definite records, and the reluctance on the part of many organi- sations to divulge what records they did have, the author has been forced to rely upon records kept in one organisation for actual cost data relative to the study being made. Two 7% H.P. motors, one a standard open motor, the other a totally enclosed fan cooled motor, driving the same kind of machines were selected for comparison. The conditions under which these motors were operating were as near identical as could be possible, the following general conditions being found true in each case. laterial being worked on - Dry cast iron. Average load on motor - 75% of full load. Hours operation per year - 9 hrs. per day, 200 days - 1000 hours. The cast iron dust thrown off during the operation was quite fine and such of the finer dust was held in suspension in the air for a short time before it finally settled to the floor. Some of this dust actually settled on the motor and in the case of the open motor clogged the air ducts and windings of the motor to such an extent that it had to be blown out with compressed air at regular intervals. The open motor was found to be running hot and probably was operating at lowered efficiency. The totally enclosed fan cooled motor was opened once each year for inspection and greased twice yearly. The only cleaning it received was that given it by the operator each day when cleaning up the machine. a The open motor was wiped off, blown out with air, and oiled at regular intervals. it less frequent intervals the oil was drained from the oil wells, the wells were flushed out and refilled with new oil, an average of fifteen minutes daily being spent in performing these operations by the maintenance crew. The motor was also disassembled, cleaned and I7. reassembled four times each.year, an average of four bearings being re- placed each year due to the abrasive action of the metallic dust which had found its way into the oil. The motor was rewound once because of grounded coils. By comparing the total of the added initial cost of the totally enclosed fan cooled motor plus the service costs plus the added power con- sumption due to lower efficiency, with the total cost of maintenance caused by the open motor, we find that the use of a totally enclosed motor in this case would have been a good investment. 71» mp. - r.r.r.c. llotor - nrr. o .75 run Load - 86%, p.r. - .73 Md.d 1n1t1‘1 (30" Of TeEeFeCe Motor ’ 55.00 Interest on added initial investment (5 yrs.) 16.80 Additional power consumption (5 yrs.) 458 KI Hrs. 0 .02 6.76 00st of greasing and inspection (5 yrs.) 4 Hrs. 6 .60 2.40 Total additional cost of the T.E.F.C..flotor Q 85.96 7} 3.2. - Open notor - err. 157.5% o .75 m1 Load, 9.1. - .73 Cost of cleaning, oiling, blowing out with air, etc. 50 Hrs. per year 0 .60 Br. (5 yrs.)890.00 12 General overhaul and clean - 4 Hrs. each u .60 per hour (5 yrs.) 26.60 12 3mm 11111“. r.p1‘°“ 0 “e90 .‘0h ‘3 ”.e’ 34.80 1 Rewind - due to grounded coils (5 yrs.) 50.00 Total cost of maintenance - 5 year period 3 205.60 By comparison the totally enclosed fan cooled motor in this particular case was found to pay 81 per cent on the added investment instead of the necessary 55 l/5 per cent. The 50 3.1’. motors selected for investigation were found to have .been operating under practically the same conditions. The time required for the necessary maintenance, however, was greater because of the sise of the motor. 50 H.P. r.s.r.o. liotor - srr. 89$ o .0 Pull Load, 9.3. - .ev Added initial cost 5 175.00 Interest on added initial investment (5 yrs.) 52.50 Additional power consumption (5 yrs.) 24.64 Cost of greasing and- inspection (5 yrs.) 5 Hrs. 0 .60 5.00 Total additional cost of ammo. lotor (5 yrs.) 6 255.54 :6 mp. - Open llotor - err. 90% e .s run Load, 9.1. - .67 Cost of oiling, wiping, cleaning, 20 lin. per day, 600 days 0 .60 per Br. (5 yrs.) 8 133.00 12 General overhaul and clean 5 Hrs. each s .60 per Br. (5 yrs.) 56.00 6 hearing linings replaced at $5.40 each (5 yrs.) 52.40 1 Rewind - due to grounded coils and overheating 108.00 Total cost of maintenance (5 year period) O 296.40 18. Again we find that the totally enclosed fan cooled motor is a profitable piece of equipment, the returns on the investment, however, are not as great as in the case of the smaller motor. These cases are indicative of what the totally enclosed fan cooled motor will do under like circumstances. lum- erous cases could be cited here where the same type of motor had been as profitable an investment under conditions probably less serious. The fact still remains, however, that conditions vary with each application and those making the decision as to which type of motor to use should study the conditions carefully before deciding. An investment, to be profitable, must produce results and because it does in one case is not infallible proof that it will in others. Some industrial engineers have, in the past decided that if one totally enclosed fan cooled motor was a paying investment that they should use nothing else irrespective of location or conditions in order to obtain what they ten standardisation throughout their entire plant. hperieme ' has taught them, however, that they achieved standardisation and inter- changeability to a certain extent but at an exorbitant cost. There are sane points about the cases cited which should be mentioned. Objection might be raised that in the case of the 50 LP. motor, the item for rewinding the motor might have been avoided by more careful maintenance, in which the totally enclosed fan cooled motor would not have been a paying investment. hperience has shown that, in the plant in which the two motors were located, any motor exposed to similar conditions rarely serves more than two years without developing trouble from broken down insulation with consequent grounded coils if not an actual burnout of the winding. Injurious agents such as fine metallic dust, caustic solutions, cutting oils and compounds, acid fumes and the like, once they reach the windings are almost impossible to entirely re- move when the motor is cleaned. The residue is therefore left in the crevices and corners of the windings, in the oil wells and around the leads and, of course, continue to exert their injurious effect on the IOTOI’e In both of the cases cited, no mention was made and no account taken of the possible loss due to interrupted production while the open motor was being serviced. eases have been found where the interruption to production or service has been productive of losses greater than the cost of a totally enclosed fan cooled motor. To avoid this possibility it has been common practice in many industries to have what are popularly called "Back up“ motors in stock in sufficient numbers in the proper ratings to be available for replacement in case a motor fails. This is expensive insurance but has been the only known means of guarding “that long and expensive interruptions to service or production. These points are of greater importance in large plants or estab- lishments than in small plants. The freedm from failures which is characteristic of a totally enclosed fan cooled motor with less necessity for back up motors is one point in favor of those she argue for complete standardisation on totally enclosed fen cooled motors. It does not, however, prove the point entirely. It can safely be said that a totally enclosed fan cooled motor is not justified where a standard open motor will operate satisfactorily and economically. 19. lo attempt has been made to discuss in detail the use of the "explosion proof motor" nor to determine to what extent the extra in- vestment as shown on the initial cost sheet can be justified. As the study of the totally enclosed fan cooled motor progressed, it became evident that the applications of explosion proof motors were in most in- stances special problems and should be considered and studied as such. In reality, whenever the occasion arises in which an explosion proof motor is considered necessary, the risks involved due to the possible loss of life, loss of material, buildings and equipment is so great that the extra investment is a negligible quantity. 20. 88 a. 3.9.8 5 «.8 Evan 30.3.33 no: mad» 8...» 8.8» 8.2.» 8.»: 8.3» 8 an.» «0.2. 8.8» 8.8» 8.8» 8.8.» 8.8» 8 ES «or.» 8.5» 8.»: 8.8» 8.8» 8.3» 8 u»: and» 8.8» 8.»: 8.8» 8.»: 8.8» e» um: no.8 8.2.» 8.2: 8.3» 8.3» 8.8» 3 a». «.3» 862 8.8a 8.8» 8.3» 8.8» 8 no: u»... 8.»: 8.2. 8.8» 8.3» 8.8" 3 no» a}: 8.3a 8.8 8.3» 8.5.. 8.3a 3 «8 8.8 8.8 8.8 8.3» 8.5.. 8.1: «a $33 5.8 8.3 8.8 8.8a 8.8” 8.8 » «8a .6» 8.2. 8.5. 8.»: 8.8 8.2. » 86.: no.3 8.8 8.2 8.»: 8.8 8.8 a «a: 3.». 8.3. 8.8.» 8.38 8.2.» 8.8. em 893 .5. add...» «8.2 .nm 6:3.“ 89..» .5» 6.33 fled. flaw. 3 2.85» a. do» :8 .32 5.3 333 33:84 358 .m.m.m 82 8 83a .53 88 Sam: T. CONCLUSI ON The objective of this thesis, as has been previously stated, was to study the practical application of the totally enclosed fan cooled motor and to determine the economical limit to ohich industrial manage- ment might invest in this type of equiment. The material presented in the foregoing discussions, together with the successful applications of this type of motor Ihich were encountered while making this study leads to the following conclusions. The totally enclosed fan.cooled motor is a practical solution to the problem of providing protection for the live parts of an electric motor from outside injurious agents. It is economical to use this type of motor in the range of sises included in the analysis of costs in all localities in which the in» jurious agents are present in sufficient quantity to necessitate extra maintenance costs. In all sises above the range included in the cost analysis, special consideration should be given to each individual case. ”'2’“ ROOM'USE ONLY mom. to . 26 5‘