Electric Machine


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Electric Machine

 

a machine that converts mechanical energy into electric energy, converts electric energy into mechanical energy, or transforms electric energy by changing the type of current or by altering such parameters as voltage and frequency. The operation of electric machines is based on electromagnetic induction and the laws governing the interaction of electric currents and magnetic fields.

Electric generators convert mechanical energy into electric energy, whereas electric motors convert electric energy into mechanical. In accordance with Lenz’s law, generators and motors are reversible—that is, can operate both as a generator and as a motor. Commercially produced electric machines, however, are usually intended for specific duty (seeALTERNATING-CURRENT MACHINE; DIRECT-CURRENT MACHINE; ASYNCHRONOUS ELECTRIC MACHINE; SYNCHRONOUS MACHINE; and COMMUTATOR MACHINE).

The conversion of current, frequency, number of phases, and voltage is achieved with rotary amplifiers, transformers, and rotary converters (seeCONVERSION TECHNOLOGY).

Electric machines also include special-purpose machines, such as magnetos, welding generators, tachometer generators, and traction motors.

Table 1. Characteristics of the electric locomotives most commonly used in the USSR (1977)
SeriesCurrent SystemType of serviceNumber of wheel pairsWeight (tons)Power rating of motors1 (kW)Tractive effort (tons)Maximum speed2 (km/hr)
11-hr rating, as determined by, for example, motor design and cooling conditions
2Maximum speed in service, as determined by locomotive design
VL80K, VL80T, VL80R ...............25-kV single-phase AC at 50 HzFreight81846,52045.1110
VL60K ...............sameFreight61384,45031.8100
ChS4T ...............samePassenger61265,10017.4160
ChS4 ...............samePassenger61265,10017.4160
VL10 ...............3-kV DCFreight81845,20039.5100
VL8 ...............3-kV DCFreight81804,20035.2100
VL22M ...............3-kV DCFreight61322,40023.975
ChS2T ...............3-kV DCPassenger61264,62019.4160
ChS2 ...............3-kV DCPassenger61234,20016.5160

REFERENCES

Kostenko, M. P., and L. M. Piotrovskii. Elektricheskie mashiny, 3rd ed., part 2. Leningrad, 1973.
Vol’dek, A. I. Elektricheskie mashiny, 2nd ed. Leningrad, 1974.

M. D. NAKHODKIN

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