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) | |||||||
|---|---|---|---|---|---|---|---|
| Series | Current System | Type of service | Number of wheel pairs | Weight (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 Hz | Freight | 8 | 184 | 6,520 | 45.1 | 110 |
| VL60K ............... | same | Freight | 6 | 138 | 4,450 | 31.8 | 100 |
| ChS4T ............... | same | Passenger | 6 | 126 | 5,100 | 17.4 | 160 |
| ChS4 ............... | same | Passenger | 6 | 126 | 5,100 | 17.4 | 160 |
| VL10 ............... | 3-kV DC | Freight | 8 | 184 | 5,200 | 39.5 | 100 |
| VL8 ............... | 3-kV DC | Freight | 8 | 180 | 4,200 | 35.2 | 100 |
| VL22M ............... | 3-kV DC | Freight | 6 | 132 | 2,400 | 23.9 | 75 |
| ChS2T ............... | 3-kV DC | Passenger | 6 | 126 | 4,620 | 19.4 | 160 |
| ChS2 ............... | 3-kV DC | Passenger | 6 | 123 | 4,200 | 16.5 | 160 |
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