Document 5L703o2jDYrz7qdGoeX0q9wL0

628 - CHAPTER 35 ' 1948 Guide Typical Specifications for Wound Rotor Motors.'. f208i - , -Hp---------"... _RPM, {go} Cycles, {^l Volts, {|} Phase, .Wound Rotor 550.' Induction Motors For Driving...::._.:______ 1.:......... Motor Shall'Be Arranged for '- .'(Application) . Mounting And Shall Be Provided. With A___!_____________ ___________ l vertical j (Open, Splashproof, etc.) Typeof Enclosure, NEMA {q^s b} Insulation:and {sj^ye} Bearings. . Typical Specifications for Synchronous'Motors Hp,_______ RPM,_____Per Cent P.F.,:_____ Vohs, {|| Phase, {^} Cycles, (Belted] Synchronous Motors of the | Coupled ] Type for Driving. (Engine J (Application) Motor Shall be Arranged for {vertha"13'} Operation and Shall. Be Provided With A____________ ...........i__ _______ ;..Type of Enclosure. Motor Shall be Capable (Open, Splashproof, etc.) of Developing A. Starting Torque of _____ Per Cent Full Load Torque, A Pull-In Torque of__ _Per Cent Full Load Torque; And A Pull-Out Tbrque of Per Cent Full Load Torque. The Motor Field Shall Be Excited From A (Direct Connected Exciter' Belted Exciter. Which (Shall \Shall \ Not/ Be Included With The Motor. M-G.Set Exciter . d-c Bus , the,power factor. With purchased,power,,it.the rates, include a clause embodying, a. penalty for low power factor, or, a bonus for high-power factor, the.saving in power costs may often,make a very good return.on. the investment required.for the corrective equipment. Synchronous motors are' used to drive fans, blowers, pumps, compres sors and- other applications. Compressor; applications having a high peak'torque, require the use of flywheels to smooth out power'peaks; and should always be referred-to the electrical manufacturer for recommen dations. ' ........ ' ... 'Synchronous motors are provided with built-in damper windings on the rotOr and operate during the starting-period similarly to squirrel-cage mOtors. After'themot'or is nearly up td'speed;-`field excitation1 is applied arid, the `motor' draws' into step at synchronous speed. After excitation'- is apjplied the mOtor runs at exactly constant rspeed and will remain at this speed until a load approaching the pull-out load is reached;'whereupon the motor, pulls out-of synchronism and stops.; s''' In applying synchronous motors consideration must be given to the torque the motor can develop on pull-in, that is, at the.instant when field Motors: and Motor Controls 629 excitation is applied. Table 2 tabulates typical application requirements of synchronous motor drives, listing starting, pull-in, and pull-out-torques: Typical specifications for synchronous motors are shown: On page 628. Multi-Speed, motors provide flexibility in many types of drives;-'-, Syn chronous'motors can be furnished only with a 2 to 1 ratio in speed, single winding. Squirrel-cage induction motors may be 2, 3 or 4 speed. Two-speed induction motors are usually of single winding type, haying a 2 to Lspeed ratio such as 600 rpm and 1200 rpm, or may be double winding. Three-speed induction motors are always two winding, and four-speed motors are usually two winding with a 2 to 1. speed, ratio Fans Table 2. Typical Application Requirements of Synchronous Motor Drives Showing Starting, Pull-In and Pull-Out Torques Method op Motor to Load Starting Conditions Torques Start Pull- Pulling in Out Rbmabk Exhaust and Ventilating Coupled or Belted Usually . Loaded : . 50 60-125 150 WK* of Fan Must be Considered Cydofdal Positive Coupled or Engine Type S3 * Blowing Engines Reciprocating Engine Type- Unloaded .Unloaded 40-60 40-60 150 40 40-60 150 Two-Speed Motors Sometimes Used Turbo High Speed Direct Connected or Step Up Gear Unloaded *: 30 (Intake Closed) 50 150 WR* of Blower Must be Considered Air Engine Type Unloaded 40 40 150 . . Flywheel Effect Important 15 Ammonia and Ammonia High Speed--Belted Unloaded Low Speed--Engine Type (By By-Pass) 40 40 150 Flywheel Effect Important Booster Occasionally Coupled a Eo U Freon High Speed--Belted Low Speed--Engine Unloaded 45 60 150 Flywheel Effect (By By-Pass) Important Gas Highspeed--Belted . Unloaded. 40 40 150 Flywheel Effect Reciprocating" : Low Speed--Engine (By By-Pass) Important