Document B5Nx7Z69r543J450m4L6qdobj

630 Chapter 35 Table 1. Classification of Motors 1945 Guide Power Supply Type Charac- Full Voltage Starting Torque Starting Current Hp -Range Type of Application Sfftt FOOTNOTEf Constant Speed Drives 1. Shunt D-C 2. Compound 3. Series Constant formal ' Variable High Variable High Vormal Ml wxmitthroller) Normal AU [with controller) Normal Small (with controller) o) Fans and c) centrifugal pomps and centrifugal compressors (6) (c) (e) Reciprocating pumps and fre- quent or hand starting (d) Fans direct con nected. . 4. Squirrel-Cage Constant General Purpose Class A Normal 0.8-1.5 times ' 5. Squirrel-Cage . Class B Constant Normal 08-1.5 times 6. Squirrel-Cage Class C Constant High 2-2.6 times Polx- . WlASE A-C . - 7. Wound Rotor, Constant or Variable High : 1-2.5 times High AU . 6-8 times Normal Medium. 5-6 times - Small Normal Medium 5-^6.times Small Low 1-3 times with sec ondary control AU : (a) Fans and (e) centrifugal pumps and centrifugal compressors (c) Fans and centri fugal pumps and centrifugal com pressors (5) Reciprocating pumps (e) and compressors started loaded - () Hoists () reciprocating pumps and com pressors (c) and frequent (e). or hand start 8. Synchronous High Speed' Exactly. . Constant Normal 0.75-1.75 times Normal 5-7 times Medium . Large (d) Fans and cen trifugal pumps and . centrifugal com pressors . 9. Synchronous Low Speed Exactly. Low Constant 0.3-0.4 times Low Medium 3-4 times Large (a) Reciprocating compressors start ing unloaded ' 10. Capacitor Constant High-. Normal : Small (5) `Pumps and compressors 11. Capacitor Fan Constant Normal. Normal Small (o) Fans, centrifugal pumps Single PHASE A-C 12. Capacitor Start Constant Induction Run 13. Repulsion : Induction Constant High High Normal. Normal Small Fractions Medium Small (a) Fans (b) pumps and compressors (a) Fans (b) pumps and compressors 14. Split Phase ______ _____ __ Constant and Adjust able . Normal Normal Fractiona (o) Fans (b) pumps and compressors . (d) fans--direct toA. pDprliivceastiohnavsiing 1medium or low starting torque and inertia (IFR*) such as fans and centrifugal pumps or reb.cipDrroivceastinhgapvuinmgphsigahndstcaormtinprgestosorqrsuessta, rsteudchuansloraedceipdr.ocating pumps and compressors started loaded. c. Similar to (<?) except where frequent or band starting (large JFR5) requires a higher starting and accelerating torque. 3. Fans direct connected. c. Stoker drives. * Motors and Motor Controls Table 1. Classification of Motors--(Concluded) 6S1 Type Speed Charac teristics Full Voltage Starting Torque Starting Current Hp Range Application ' SEE FOOTNOTEf D-C Adjustable Speed Drives 15. Shunt Field Adjustment Constant Normal 16. Armature Resistance Adjustment Variable. 17. Variable Voltage Constant Control Normal Normal Normal AU (with controller) Normal All (with controller) Normal AU (a) Fans and (e) centrifugal pumps (o) Fans and (e) centrifugal pumps (d) Fans and centrifugal pumps Poly phase A-C 18. Squirrel-Cage High Slip. Transformer Adjustment Variable 19. Squirrel-Cage Constant Separate Wind Multiing or Regrouped Speed Poles 20. Wound Rotor, Variable External Secondary Resistance Normal Normal or High ' High Normal Normal or Low Low Medium Small All All (a) Fans (a) Fans (6) pumps and (c) compressors ' (al Fans (h) centrifugal pumps and compressors 21. Repulsion Variable High Single *Phase A-C 22. Capacitor Low Torque Tapped Winding 23. Capacitor Low Torque Trans former Adjust ment Variable, Two Speed Variable 24. Split Phase Constant Regrouped Poles Low Low Normal Normal Normal Low Normal Low and (a) Fans--centrifugal Fractional pumps (5) compressors Fractional (d) Fans, direct Fractional (d) Fans Fractional (d) Fans DIRECT CURRENT MOTORS Direct current motors are classified (see Table 1) under three headings, depending on the type of winding: shunt wound, compound.wound, and series wound. Shunt Wound motors, being suitable for application to fans, centrifugal pumps, or similar equipment where the amount of starting torque required is relatively small, are used for the majority of direct current applications. in the field of . heating, ventilating, and air conditioning. They may be used on reciprocating pumps and compressors if started under unloaded conditions. Without auxiliary control the shunt wound motor is designated as constant speed.* Fig. 1 illustrates the characteristics of direct current motors, showing speed, horsepower, and torque as a function of current. The speed regulation* of small size shunt wound motors from % hp to 5 hp is 12 per cent as specified by the NEMA while on larger motors it is 10 per cent. Refer to Glossary at end of chapter.