Table of Contents
Disadvantages or Demerits: Synchronous motors are inherently not self starting motors and needs some arrangement for its starting and synchronizing. When loading on the synchronous motor increases beyond its capability, the synchronism between rotor and stator rotating magnetic field is lost and motor comes to halt.
What are the advantages of the synchronous motor?
The advantages of the synchronous motor are the ease with which the power factor can be controlled and the constant rotational speed of the machine, irrespective of the applied load. Synchronous motors, however, are generally more expensive and a d.c. supply is a necessary feature of the rotor excitation.
What are the disadvantages of synchronous compensator?
Although, synchronous condenser system has some disadvantages. The system is not silent since the synchronous motor has to rotate continuously. An ideal load less synchronous motor draws leading current at 90o(electrical).
What are the main characteristics of synchronous motor?
Main Features of Synchronous Motors Synchronous motors are inherently not self starting. The speed of operation of is in synchronism with the supply frequency and hence for constant supply frequency they behave as constant speed motor irrespective of load condition.
What are the benefits of synchronous motor in real world application?
usually, synchronous motors are used for applications where precise and constant speed is required. Low power applications of these motors include positioning machines. These are also applied in robot actuators. Ball mills, clocks, record player turntables also make use of synchronous motors.
What is the main disadvantage of synchronous motors?
Disadvantages or Demerits: Synchronous motors requires dc excitation which must be supplied from external sources. Synchronous motors are inherently not self starting motors and needs some arrangement for its starting and synchronizing. The cost per kW output is generally higher than that of induction motors.
Which is better synchronous or asynchronous motor?
Efficiency of Synchronous motor is greater than Asynchronous motor. By changing excitation the power factor of the Synchronous motor can be adjusted accordingly as lagging, leading or unity, whereas Asynchronous motor runs only at a lagging power factor.
What are the advantages of synchronous compensator?
Advantages of synchronous condenser: The reactive power can be adjusted continuously. They are giving better performance than the static capacitor in the high voltage system. Maintenance-free. A high degree of safety can be maintained.
Why synchronous motors are not self starting?
Above a certain size, synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator. Once the rotor nears the synchronous speed, the field winding is excited, and the motor pulls into synchronization.
What is the ideal power factor?
The ideal power factor is unity, or one. Anything less than one means that extra power is required to achieve the actual task at hand. All current flow causes losses both in the supply and distribution system. A load with a power factor of 1.0 results in the most efficient loading of the supply.
Why the speed of synchronous motor is constant?
When you supply 60 Hz (or 50 Hz), the motor will spin at one speed, which is dependent on the number of poles. This rotational speed will be constant with different mechanical loads, up to the point that the motor (or coupling) fails, hence it is a “constant speed” motor.
What is the principle of synchronous motor?
The principle of operation of a synchronous motor can be understood by considering the stator windings to be connected to a three-phase alternating-current supply. The effect of the stator current is to establish a magnetic field rotating at 120 f/p revolutions per minute for a frequency of f hertz and for p poles.
How does a synchronous motor start?
The motor is first started as a slip ring induction motor. The resistance is gradually cut-off as the motor gains speed. When it achieves near synchronous speed, DC excitation is given to the rotor, and it is pulled into synchronism. Then it starts rotating as a synchronous motor.
Which is main application of synchronous motor?
Synchronous motors are normally used in applications in which a constant and precise speed is required. Typical applications of these low power motors are positioning machines. They are also used in robot actuators. Synchronous motors are also used in ball mills, watches, record players, and turntables.
What are the disadvantages of synchronous learning?
Main disadvantages of synchronous learning: Both the student and the instructor have to adhere to time schedules. Much of the training depends on the quality of the instructor. Students may not receive individual attention if other students are also in need. The learning pace is set by the instructor, not the students.
What are the special applications of an over excited synchronous motor?
Application. An over-excited synchronous motor has a leading power factor. This makes it useful for power-factor correction of industrial loads. Both transformers and induction motors draw lagging (magnetising) currents from the line.
What are the causes and disadvantages of low power factor?
Now, In case of low power factor, current will be increased, and this high amount of current will lead to the following disadvantages. Large Line Losses (Copper Losses): Greater Conductor Size and Cost: Poor Voltage Regulation and Large Voltage Drop:.
What is the difference between synchronous and asynchronous motors?
The synchronous motor is a type of AC motor that runs at synchronous speed. The asynchronous motor is a type of AC motor that runs on speed less than the synchronous speed. It operates on the principle of magnetic interlocking between rotor and stator field. it is always less than synchronous speed.
Where is asynchronous motor used?
Thus, this is all about an overview of an asynchronous motor. These motors are frequently used in 90% of the applications all over the world due to reasons like great robustness and reliability. These motors are used in different moving or rotating machines like lifts, fans, grinders, etc.
Why is it called asynchronous motor?
Because induction motor can not rotate at synchronous speed it always rotate less than synchronous speed. in short, induction motor never rotates at synchronous speed so it called asynchronous motor.
Can a synchronous motor slip?
Slip is strongly associated with synchronous speed. If the motor turned at the same RPM as the magnetic field, there would be no relative motion between the rotor and the field.
What is the application of synchronous compensators *?
Explanation: The main application of the synchronous compensators is to control the reactive powers. They are designed to speeds upto 3000 rpm.
How can we improve power factor?
The simplest way to improve power factor is to add PF correction capacitors to the electrical system. PF correction capacitors act as reactive current generators. They help offset the non-working power used by inductive loads, thereby improving the power factor.
Why Statcom is used?
The Static Synchronous Compensator (STATCOM) is used in an HVDC system to provide reactive power compensation. It makes use of the Voltage Source Converter (VSC) to synthesize a controllable sinusoidal voltage at the fundamental frequency.
