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
VL80^K, VL80^T, VL80^R ...............	25-kV single-phase AC at 50 Hz	Freight	8	184	6,520	45.1	110
VL60^K ...............	same	Freight	6	138	4,450	31.8	100
ChS4^T ...............	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
VL22^M ...............	3-kV DC	Freight	6	132	2,400	23.9	75
ChS2^T ...............	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