If the electric motor is a commutator, to increase its speed or increase the voltage or reduce the load on the shaft. But remember that, first, the power generated by the engine, in any case should not exceed that to which it was designed. And secondly, that many brushed motors, especially with sequential excitation, when working without load without reducing the voltage supply to accelerate to inadmissibly high speeds. Both threatened release of motor failure. Shunting of the field winding is a method to increase momentum, to resort to which is allowed is not always - it can cause a strong overheating of the engine.
Engines with electronic control windings, in which feedback is used often in properties very close to the manifold - is that they do not tolerate reverse polarity. If you had the electronic engine has the following properties, try to increase the speed of its rotation in the manner specified in the previous step, with all their respective limitations apply to this kind of motors.
The rotation frequency of induction motorfed directly from the mains, can also be adjusted by changing the supply voltage. But this method is extremely inefficient: the dependence of speed on voltage is very non-linear, varies greatly the efficiency. For motors of the synchronous type, this method is unsuitable. Therefore, it is better to use the so-called three-phase inverter. It allows you to regulate the speed not only asynchronous but also synchronous motors by frequency variation. Select a device of this type is that it provides in reducing the frequency of simultaneous reduction and voltage, to account for reduction of inductive resistance of the windings. There are inverters for single-phase motors with magnetic shunt, and a two-phase condenser motors.
Avoid overheating, their spacing increased speed and insulation breakdown in high voltage (including self-induction).
Advice 2 : How to reduce the speed of the motor
Electric motors allow the speed control to a considerable extent. Method of adjustment of this parameter depends on the motor type. Some engines allow adjustment in different ways and their combinations.
Control of commutator motor with a permanent magnet on the stator produce a change in voltage on the windings of the rotor. The dependence of the rotation frequency of the engine is on the voltage is close to linear.
Adjustment of engine speed with electronic control and feedback (e.g., used in computer fan) perform similarly, but remember that the dependence of the number of revolutions of the voltage will be somewhat less like linear. The reversal of such motors is not allowed.
To change the number of revolutions of the commutator motor with independent excitation, maintaining a constant voltage at the stator winding to change the voltage on the windings of the rotor.
To adjust frequency of rotation of the motor with serial excitation fed from the AC mains, use a special thyristor regulator. Many of the tools equipped with them originally. Do not use regulators, not designed specifically for such engines.
To change the speed of the synchronous motor, proportionally change the frequency of the mains voltage. By reducing the frequency and simultaneously reduce the voltage so that the current through the motor windings is not increased. If the voltage does not decrease, the current for reducing the frequency may increase because of lower inductive reactance of the windings. This regime is dangerous for the engine.
To reduce the frequency of rotation of an induction motor, use in the same way. If this is not possible (for example, in the absence of the three-phase inverter), just lower the voltage without changing the frequency. If the motor is single phase, it is convenient to use Latrom. In any case, do not use thyristor regulators in conjunction with any motors that are not manifold.