If necessary, the alternator can be applied to three-phase asynchronous motor with short-circuit rotor squirrel cage type, This decision is due to the wide availability of asynchronous motors, as well as due to the absence of such engines of collector-brush site, making such a generator is reliable and durable. If there is a convenient way to bring it into rotation, the rotor to generate enough electricity will be connected to the windings of the stator three identical capacitors.
Experience shows that such generators can run for years without needing maintenance, Because the rotor is remanence, the rotation in the stator windings of an induction ELECTROMOTIVE FORCE, and because the windings are connected capacitors to be a corresponding capacitive current, which will be a magnetizing rotor. When further rotation of the rotor will see media help, so will three-phase stator windings in the sinusoidal current.
In turbine mode must match the speed of the rotor of a synchronous frequency of the engine, which is above its working asynchronous frequencies. For example: the AIR112MV8 engine stator winding has 4 pairs of magnetic poles, so it has a synchronous frequency is 750 rpm, but when running under load, the rotor of the motor rotates with a frequency of 730 RPM because it’s induction motor. Thus, in turbine mode you need to rotate the rotor at 750 RPM.
Accordingly, for engines with two pairs of magnetic poles rated synchronous frequency is 1500 rpm, but with one pair of Poles-3000 rpm, Capacitors are selected according to the capacity of the asynchronous motor and the nature of the load. Reactive power of capacitors in this operating mode, according to their capacities, can be calculated by the formula:
For example, there are induction motor with a nominal power of 3kW with three-phase network with a voltage of 380 Volts and a frequency of 50 Hz. Therefore, full load capacitors should provide all this power. Because the current is three-phase, then we are talking here about the capacity of each capacitor, Speaking about modes of generators of the induction motor, it is important to note that at idle connected capacitors will generate reactive current that will warm the stator windings, so it makes sense to make the condenser units, and capacity building in accordance with the requirements of a specific load. Idle current, in this decision, will be significantly reduced, which would relieve the system as a whole. The reactive load-on the contrary would require additional capacitors, exceeding the estimated value of the typical reactive power factor loads.
Allowed connection of stator windings in Star for 380 Volts, and the triangle, for 220 volts. If there is no need for three phase current, you can use only one phase by connecting capacitors to only one of the stator windings, You can work with two windings. Meanwhile, remember that power, output each of windings in the load must not exceed one third of the total output of the generator. Depending on your needs, you can connect the three phase rectifier, or directly use alternating current. For convenience, it is useful to organize the indicator display measuring instruments, ampermetrami, and frequency counter. To switch the capacitors are ideal machines circuit breakers, Particular attention should be paid to safety, take into account the critical values of currents, and to calculate the cross section of the wires. Sound isolation is also an important factor of security.