Motors and generators

Pressurized motors and generators are not subject to special requirements for temperature limitations concerning windings and rotor, there are no stringent 

For large power drives, e.g. for compressors, two development areas determine the design of rotating machines  

Rated frequency 90 cps at 5400 min-1 Total weight 701 Weight of rotor 9.31 Compressor - Natural gas depletion compressor, Output pressure 65.5 bar Motor and compressor equipped with active magnetic bearings. 

Additional examples for pressurized motors are given in Figs 6.31-6.33. These examples demonstrate the great bandwidth of application of pressurization for large drives. 

Type of protection EEx ped [ib] IIC T3 Rated power 10 800 kW Rated voltage 3kV Purging volume 10.8 m3. 

In the case of both motors and generators, current must be fed or extracted from the rotating coils of wire. This is accomplished by connecting the ends of the coil to insulated collector rings which rotate against stationary brushes (Fig. 10.8). Since it is important that electrical contact resistance and friction be low, collector rings are usually made of copper and brushes of graphite. 

As the coil shown in Fig. 10.7 rotates, forces F) will vary sinusoidally from a maximum, in the position shown, to zero when the coil has rotated 90° in the motor mode. In the generator mode, the current will vary sinusoidally from a maximum value (/ ) to zero  

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Segment plate, used as insulation between copper commutator segments on direct-current universal motors and generators, accounts for the primary use for built-up mica. Phlogopite built-up mica is preferred for these segments because it wears at the same rate as the copper segments. 

The nonoriented steels are subdivided into low, intermediate, and high siUcon steels. The first contain about 0.5—1.5% siUcon, used mainly in rotors and stators of motors and generators. Steels containing ca 1% siUcon are used for reactors, relays, and small intermittent-duty transformers. 

Intermediate siUcon steels (2.5—3.5% Si) are used in motors and generators of average to high efficiency and in small- to medium-size intermittent-duty transformers, reactors, and motors. 

Molding. Mol ding is the older of the two forming methods and is used to form products ranging in size from bmshes for motors and generators to billets as large as 1.75 m diameter by 1.9 m in length for use in specialty appHcations. 

Natural graphite is required in some motor and generator bmshes. Its high conductivity, high contact drop, and anisotropy make it particularly usehil in bmshes for d-c equipment. 

MG-I Reference to a publiealion on Motors and Generators by NEMA (National Electrical Manufacturers Association. USA) which is adopted universally. 

Motors and generators ratings, constniction, testing and performance... 

NEMA/MG-1/1993 NEMA/MG-2/1989 Motor and generators ratings, construction, testing and performance Safety Standards (enclosures) for construction and guide for selection, installation and use of rotating machines ... 

Figure 6.63 Motoring and generating torque curves for a 1500/1000 r.p.m. dual-speed motor (torque and current curves for generating region are drawn for only low-speed winding)...

Secco, M.. Bressani, M. and Razza, F., Medium Motor and Generator Plant, Ansaldo Component i SPA. Italy. Progress and development trends in large induction motor stator winding insulation. 

ANSI C.37.47/1992 Specifications for distribution fuse disconnecting switches, fuse supports and current limiting fuses Motors and generators ratings, costruction. testing and performance... 

Utility system restrictions. Loeal utilities may restriet eurrent applieation for motorizing and generation of power during normal operation. 

In Division 1 areas, motors and generators must be either explosion-proof or approv ed for the classification by meeting specific requirements for a special ventilation system, inert gas-filled construction, or a special submerged unit. Although explosion-proof motors are expensive, they normally are available. Explosion-proof generators normally are not available. 

Space heaters, particularly in electrical motors and generators which may be idle for significant periods of time, can also help prevent the accumulation of moisture. Space heaters installed in classified areas must operate at temperatures below high temperature devices. 

ICS 6 Enclosures for Industrial Controls and Systems MG 1 Motors and Generators... 

MG 2 Safety Standard for Construction and Guide for Selection, Installation, and Use of Electric Motors and Generators MG 10 Energy Guide for Selection and Use of Polyphase Motors VE 1 Cable Tray Systems... 

The early development of electric motors and generators can be traced to the 1820 discovery by Hans Christian Oersted that electricity in motion generates a magnetic field. Oersted proved the long-suspected... 

Refer to the many details of standardization, applications, and design features in NEMA Standard MGl-1993, Rev. 1995 Motors and Generators and the safety and environmental requirements of the National Fire Protection Association Codes. ... 

Used by permission NEMA Standards MG 1-1978, Motors and Generators, 1974. National Electrical Manufacturers Association. 

Used by permission Motors and Generators, NEMA Standard MG 1-1993, Rev. 1, Section II, Part 12, p. 25-26, 1995. National Electrical Manufacturers Association. (Note All references to NEMA Standards are reprinted by Permission of the National Electrical Manufacturers Association from NEMA Standards Publication No. MGi-1-1993, Motors and Generators (1995) by the National Electrical Manufacturers Association, Rev. No. 2, Apr. 1, (1995),)... 

NOTE All references to NEMA Standards are reprinted hy permission of the National Electrical Manufacturers Association from NEMA Standards Publication No. MG-1-1993, Rev. No. 2, April 1, 1995, Motors and Generators. 

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