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868 CHAPTER 56 the drive-motor. Long-coupledcentrifugal pumps'v.-are mounted on a common-base:with their,nM>tor.:Theyare. as sembled at the factory, and properly aligned.-However,' all base-plates areflexible to some degree, and each pump, there fore, must be re-aligned' after installation in accordance with the' manufacturer's, instructions.. Alignment' can - be main tained only when the foundation has been correctly designed and.therbase plate has been'properly bolted to it -... ' ..The'foundation must always Insufficiently rigid for proper support of the base plate and should weigh from 134 to 3 times .the total pump weight for proper.vibiationicontroL . /: AP^UCATIONS - Heating and cooling systems, or combinations of both,-are usuaily closed systems, where the pump'or pumps circulate either; hot or chilled.water. As bog as these systems areclosed and are adequately maintained, system ooribsbn'is'no' prob lem. If the -systems are chemically treated, "AtgA chemical concentrations and leak-preventative.compounds: will directly influence .both seal and poking gland life.- The higher-the chemical concentration, - the greater will be the reduction in gland or seal life expectancy. It has been the usual practice' to place .chemical feeders across the pump-connecting it..from suction-.to .discharge. As systems .of. this type-usually, have bronze-fitted pumps,[.caustics, should-not-be-fed directly through .the pump. Chemical feeders, , when, and if necessary in; the system,,are best, installed downstream so as to feed chemicals into the discharge line rather than the suction line. This prevents collection of a high concentration of chemicals 1965 Guide And DatO 'Book in the pump during operation as well as during idle or shut down periods? If pumps'are to' be subjected to high nhpmi^i concentrations, they, should be selected accordingly. Cooling-tower pumps'also are almost always bronse-fitted centrifugal pumps. The comments in the foregoing paragraph apply, although tower systems are.dasafied as open hydraulic systems. Efoaon in the pumps'will'be excessive, if solids are permitted to concentratein'the system due to evaporation of water and coilection'of dust from the.cooling air dusk; This can be prevented by maintaining a continuous loss or ^low- down from the system during pump Operation. This keeps the accumulation of suspended solids toa minimum. Condensate pumps handle condensed steam from condensers and other heat.exchange equipment.-Since the-condensate is usually hot, a pump with the proper 'required NPSH charac- teristicamust be selected. Packing glamia or seals mustusually be suitable for operation under. vacuum-conditions., Bronae- fitted pumps are ordinarily selected. Pumps handling conden sate at high pressure and high temperatures require special materials as well' as special or panlring gland - (See Chapter 8 of the 1964'GuidbAnd DataBook.) ' ': Boiler-feed7pumps usually' take water from a'deaerating heater'or a feed-water heater and deliver it to the.boiler.Here, too; care must be taken that'the available'-NPSH at the pump' exceeds the required-NPSH; Materials used in the boiler feed pumps-must be'suitable`to withstand cbrrdrive arid-erosive' action'of treated feed-water: The pump design'will also follow the pattern for high-temperature pumps both as to materials and special cooling of glanda and bearings.' ' ['; CHAPTER 57 MOTORS AND MOTOR PROTECTION Hecfric Power Supply; Electric Motors: Types, AppTication; Motor Control; Codes and Standards; Domestic Refrigeration; Room Air Conditioners; Central Air Conditioners; Small Commercial Refrigeration; targe Commerciaf Refrigeration THE electric motor, available in many different types- mon chamber, the insulation of the unit must therefore withsuitable for various services, is now the most widely'' " stand the action of the refrigerant and the lubricating oiL used form of motive power. The equipment for starting, con trolling, and protecting these motors varies with the type - Application and with the functions it is desired to attain. Motors are divided into two general classifications, alternating-current . or direct-current, depending on the power source to be used. . When applying an electric motor, the following characteris tics are important: (X) mechanical arrangement including position of motor and shaft, portability desired, drive connec ELECTRIC POWER SUPPLY tion, and space limitations; (2) speed range desired; (3) horse power requirement; (4) torque; (5) inertia; and (6) frequency The following characteristics of the power supply are im portant; (1) whether current is alternating or direct, (2) voltage, (3) the number of phases of alternating current, (4) alternating-current frequency, (5) voltage regulation, (6) continuity of power. Alternating-current (a-c) is available throughout the UJ3.A: Dtred-eurrent (d-c) is still used in some parts of the country. Hie various types of electrical power supply in tire UBA: of starting. Motor characteristics frequently used are gener ally presented in curve form (Fig. 1). Torque. The torque required to operate the driven machine at every moment between initial breakaway and final shut down is important in determining the type of motor. The torque available at zero speed or standstill, the starting torque, depending upon the design of the motor,-may be-less than 100 percent, or as high as 300 percent of full-load are shown in Table 1. Alternating-current must be used in hermetically-sealed Table 1 .... Types of Bectrical - Power ' Supply in the refrigeration compressors. Otherwise the electric arcing at the United States* commutator of d-c motors would result in breakdown of the refrigerant into corrosive materials. Motors are usually guaranteed to operate satisfactorily and Supply to 5yriem Kind of Motor Conmoiify AvaBabtm Voltage a fmqA to deliver their full horsepower at the rated frequency and a voltage 10 percent above'or below rating; or at the rated 2-wire, 1-phase, ungrounded 1-phase A-C . 115 and 230 voit or one conductor grounded or D-C 120 and 240 D-C: voltage and plus or minus 5 percent frequency variation. A-C or D-C Table 2 shows the effect of voltage and frequency variation on induction-motor characteristics. 3-wire, 1-phase A-C or D-C 1-phase A-C grounded neutral or D-C 120/240 DC 115/230 A-C Types RECTR1C MOTORS 3-wire, 2-phaae A-C un 2-phase A-C 220grounded or one conductor grounded The electrical industry classifies motors as fractional hp and integral hp. Fractional hp motors have ratings of less than l hp at 1700 .to 1800 rpm, and are available in a wide variety of types and sizes depending upon the application. In refrigeration and air conditioning applications, mostly single-phase fractional hp motors arc used. Integral hp motors are largely single-phase through 6 hp. Larger motors are polyphase or use direct-current. Table 3 lists motors used for hermetic-compressor and fandrive. All motors listed are suitable for either direct or belt drive, except shaded pole motors and permanent-split-capaci tor motors which can be used for direct.drive only. Compressor motors are either complete induction motors or hermetic motors.'A hermetic motor consists of a'statorand rotor without shaft, end shields or bearings for installation in refrigeration condensing units of the. hermetically sealed type (NEMA). With tire motor and compressor sealed, in a com- Tbe caaexal rqjxxnibflity for this chapter ia *T**f~--1 to TC 10.4, Electric Motor* Opes ana Hermetic. 4-wire, 2-phase A-C grounded or ungrounded 2-phase A-C 220 5-wire, 2-phase A-C grounded neutral or un grounded 2-phase A-C 220 3-wire, 3-phase A-C ungrounded 3-phase A-C 220, 440, and 550 3-wire, 3-phase A-C' one 1-phase A-C conductor grounded and 3-phase A-C 110 and 220 l-phase 220 3-phase 3-wire, 3-phase A-C grounded neutral 4-wire, 3-phase A-C grounded neutral or ungrounded 3-phaseA-C 222/440, 550 ' ' 1-phase A-C and 3-phase A-C 120 1-pbase 208 3-phase *-Typcc cf power *uppiy in dtt t&roaghrot tbc waridcn&rtcdinc pebtiJdh. SWtric CwTtni Abn>ad (United Sutec DcMrtm>t of Commerce). 869