Name
Sobol Alexander Nikolaevich
Scholastic degree
•
Academic rank
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Honorary rank
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Organization, job position
Kuban State Agrarian University
Web site url
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Articles count: 2
In the article, the following items are represented: mathematical formulation of system including: asynchronous generator with cage rotor, condenser’s for excitation, induction load. Electromagnetic and electromechanical processes of induction motor’s connecting and feeding are described. Equations of voltage stability, equations of current, equations of rotor are used for describing of electricity circuits of generator
It is estimated that (85-95%) of the electric motor
failures occur due to damage to the stator winding. In
this case, more than 90% of damage are because of
interturn short circuits. Short circuits in stator windings
of stand-alone asynchronous generator change the base
magnetic flux incidentally, so the probability of its long
work with such kind of damage is great. A latent
failure, existing as a loop closure, significantly reduces
the reliability of the generator as a backup power
source. Now sensitive protections of asynchronous
generators do not exist, since it is believed that in the
case of short circuits (short circuit), the generator loses
its excitation, and protection is not required for it.
Identification of information signs of short-circuit
currents in the stator winding of an asynchronous
generator makes it possible to develop relay protection.
The main principle of detection of stokes closures in
the stator winding of an asynchronous electric motor is
the measurement of the emerging asymmetry of the
stator currents. It has been established that in the case
of short-circuit faults, the asymmetry of the currents
and voltages is not large and comparable to the
asymmetry in the AAG load circuit. This does not
allow performing a protection that reacts to this
asymmetry. You can also say about changing the
harmonic spectrum of currents and voltages. To build
protection, it is necessary to use highly sensitive
circuits for detecting the asymmetry of a three-phase
system of currents and voltages, as well as distortion of
the shape of currents and voltages, for example, by
harmonic analysis. Do not exclude the possibility of
using other protection devices, such as reacting the
vibration of the case of an induction generator in the
event of damage to the stator winding