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DC Fan Control Counter Electromotive Force Is Very Small, Starting Current Is Very Large
- Aug 16, 2017 -

The rotor includes: armature core, armature (shu) windings, commutator, shaft and fan. Rotor composition: DC motor rotor part of the armature by the arm, armature, commutator and other devices,DC Fan Control the following parts of the structure of a detailed description.

1. Armature core part: its role is embedded armature winding and through the magnetic flux, in order to reduce the motor work armature core in the attack of the eddy current loss and hysteresis loss.

2. Armature part: the role is the onset of electromagnetic torque and induced electromotive force, and the energy conversion. Armature windings have many coils or glass filaments of flat steel or enameled wire.

3. commutator, also known as commutator, in the DC motor,DC Fan Control its role is to brush the DC power supply current into the armature winding within the communication current, so that the tendency of electromagnetic torque stability in the DC In the generator, it converts the armature winding communication electromotive force into the output electromotive force at the brush end.

The commutator consists of a plurality of chips consisting of mica insulation, and the armature windings are connected at both ends of each coil to the two commutator segments. DC commutator in the role of the commutator coil in the alternating electric heat into the brush between the DC electromotive force, there is a current through the load, the DC generator to the load output power,DC Fan Control while the armature coil also There must be a current through.

It interacts with the magnetic field to generate electromagnetic torque, which tends to be contrary to the generator. The original idea simply suppresses the magnetic field torque. Therefore, the generator output power to the load also from the original idea of the output of mechanical power, the end of the DC generator will be converted into electrical energy role.

As the motor armature circuit resistance and inductance are small, and the rotating body has a certain mechanical inertia,DC Fan Control so when the motor is connected to power, the start of the armature speed and the corresponding back electromotive force is very small, starting current is very large. Up to 15 to 20 times the rated current.

This current will disturb the grid, the unit is subject to mechanical shock, commutator sparks. So the direct closing start is only applicable to the power of not more than 4 kilowatts of the motor (starting current for the rated current of 6 to 8 times). In order to limit the starting current,DC Fan Control often in the armature circuit into a specially designed variable resistor, the principle of wiring shown in Figure 1.

In the process of starting with the continuous increase in speed in time to step by step to shorten the blocking resistor, so that the starting current is limited to a certain allowable value. This starting method known as the series resistance starting, very simple, light equipment,DC Fan Control widely used in a variety of small and medium-sized DC motor.

But because of the energy consumption during start-up, it is not suitable for frequent start-up motors and medium and large DC motors. However, for some special needs, such as urban trams often start, in order to simplify the equipment, reduce weight and ease of operation and maintenance, usually using string resistance starting method.

On the larger capacity of the DC motor,DC Fan Control usually using the voltage drop start. That is, by a separate adjustable DC power supply motor armature power supply, control the power supply voltage can make the motor smooth start, but also to achieve speed. This method is more complicated power supply equipment.