Неисправности электродвигателей и способы их устранения.
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Motors mау have different faults. А faulty motor does not start, or, when it is started, it operates at an excessive speed. Its brushes mау spark and its windings and the commutator mау bе overheated and burnt. Besides, а motor mау produce an abnormal noise, etc. Аll these and other faults should bе detected and repaired. In case the motor does not start it mау have different faults (see the table):
Таblе
Possible causes of faults. Ways of repair
1. Fuses аrе faulty. 1. Replace the fuses.
2. Motor is overloaded. 2. Reduce motor load.
3. Circuit in armature winding has an open. 3. Repair the armature winding.
In case the motor, when started, stops:
1. Rheostat is shorted. 1. Check the rheostat and repair it.
2. Rheostat switches from one position to another. 2. Slow down operation of rheostat handle.
Brushes mау spark in case:
1. Motor is overloaded. 1. Reduce the load and re move overload.
2. Brushes are in poor condition. 2. Replace the brushes.
3. Pressure is low. 3. Adjust the pressure.
4. Pressure is excessive. 4. Adjust the pressure.
In case the armature winding is overheated:
1. Motor is overloaded. 1. Remove the overload.
2. Ventilation fails to operate properly. 2. Check for slowing down the speed ofthe motor.
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In case of abnormal motor speed:
1. Motor is overloaded. 1. Reduce the load.
2. Rotor circuit has poor contact. 2. Repair the shorting mechanism.
In case the rotor brushes against stator:
1.Rotor brushes against stator. 1. Adjust air gap.
Тема № 3 Difference Between Electric Motor and Generator
Разница между электродвигателем и генератором.
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Electric Motor vs Generator
Electricity has become an inseparable part of our life; more or less our whole lifestyle is based on the electrical equipment. Energy is converted from many forms to the form of electrical energy, to power up all these devices. The electric motor is a device which converts mechanical energy into electrical energy. On the other hand, devices are used to transform electrical energy into mechanical as required. The motor is the device that performs this function.
More about Electric Generator
The fundamental principle behind the operation of any electrical generator is Faraday’s law of electromagnetic induction. Idea stated by this principle is that, when there is a change of the magnetic field across a conductor (a wire for example), electrons are forced to move in a direction perpendicular to the direction of the magnetic field. This results in generating a pressure of electrons in the conductor (electromotive force), which results in a flow of electrons in one direction. To be more technical, a time rate of change in magnetic flux across a conductor induces an electromotive force in a conductor and its direction is given by Fleming’s right hand rule. This phenomenon is used largely to produce electricity.
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To achieve this change in magnetic flux across a conducting wire, magnets and the conducting wires are moved relatively, such that flux varies based on the position. By increasing the number of wires, you can increase the resulting electromotive force; therefore, wires are wound into a coil, containing a large number of turnings. Setting either the magnetic field or the coil in rotational motion, while the other is stationary, allows continuous flux variation.
The rotating part of the generator is called a Rotor, and the stationary part is called a stator. The emf generating part of the generator is referred to as the Armature, while the magnetic field is simply known as Field. Armature can be used as either the stator or the rotor while the field component is the other. Increasing the field strength also allows increasing the induced emf.
Since permanent magnets cannot provide the intensity needed to optimize the power production from the generator, electromagnets are used. A much lower current is flowing through this field circuit than the armature circuit and lower current pass through the slip rings, which keep the electrical connectivity in the rotator. As a result, most of the AC generators have the field winding on the rotor and the stator as the armature winding.
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