Table of Contents
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 uses of synchronous motor?
In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. These machines are commonly used in analog electric clocks, timers and other devices where correct time is required. In higher power industrial sizes, the synchronous motor provides two important functions.
What is the main purpose of a synchronous motor in practice?
Synchronous motors are often used in large plants to drive the central air compressor. A large synchronous motor can be used to control the power factor of the whole plant, compensating the lagging power factor of a large number of medium and small induction motors.
Where is synchronous motor used in ship?
The synchronous machine on ship is normally not used as a motor in ship applications, with exception of large propulsion ship drives, typically > 5 MW directly connected to propeller shaft, or >8- 10 with a gear connection.
Can a synchronous motor be used as a generator?
Figure 1 shows a cross-sectional view of a salient-pole synchronous machine. The armature windings are shown as concentrated windings, but in reality, they would be distributed. Such machines can be operated either in Motor or Generator mode.
What are the main parts of synchronous motor?
The Construction of Synchronous Motors A synchronous motor is generally made up of two parts, a stator the stationary part of the machine that carries the armature winding in which the voltage is generated, and a rotor the rotating part of the machine that produces the main field flux.
What are the main characteristics of synchronous motors?
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.
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.
What is the working 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.
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 are 3 types of motor controls?
There are mainly there are three types of motor control circuits: Direct On Line Starter (DOL starter) Star Delta Starter. Auto Transformer Starter.
Which motor is used in ship?
3 Phase Induction Motor – Construction and Working. The popularity of 3 phase induction motors onboard ships is because of their simple, robust construction, and high-reliability factor in the sea environment. An induction motor can be used for different applications with various speed and load requirements.
What are different types of motors?
Some of the most common electric motors used today include: AC Brushless Motors. AC brushless motors are some of the most popular in motion control. DC Brushed Motors. In a DC brushed motor, brush orientation on the stator determines current flow. DC Brushless Motors. Direct Drive. Linear Motors. Servo Motors. Stepper Motors.
Can a generator become a motor?
In principle, any electrical generator can also serve as an electric motor, or vice versa. In hybrid vehicles and other lightweight power systems, a “motor–generator” is a single electric machine that can be used as an electric motor or a generator, converting between electrical power and mechanical power.
What is the difference between synchronous motor and generator?
Synchronous Motor: The main difference between the two is the sign conventions. Current reference is out of the plus terminal of the generator, but into the plus terminal of the motor. This leads to different diagrams for various DC excitations of the field as shown below.
Why we use synchronous motor as a generator?
Synchronous generators are commonly used for variable speed wind-turbine applications, due to their low rotational synchronous speeds that produce the voltage at grid frequency. Synchronous generators can be an appropriate selection for variable speed operation of wind turbines [166,167].
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.
What is meant by synchronous speed?
: a definite speed for an alternating-current machine that is dependent on the frequency of the supply circuit because the rotating member passes one pair of poles for each alternation of the alternating current.
What are the two types of synchronous generators?
Types of synchronous machines Hydrogenerators : The generators which are driven by hydraulic turbines are called hydrogenerators. These are run at lower speeds less than 1000 rpm. Turbogenerators: These are the generators driven by steam turbines. Engine driven Generators: These are driven by IC engines.
What are the types of synchronous motor?
Synchronous motors can be classified into two types based on how the rotor is magnetized.This type of synchronous motor is divided into three categories and is available in three designs, each of which has unique features: Hysteresis Synchronous Motors. Reluctance Synchronous Motors. Permanent Magnet Synchronous Motors.
What is difference between synchronous and asynchronous motor?
Synchronous motor is a machine whose rotor speed and the speed of the stator magnetic field is equal. Asynchronous motor is a machine whose rotor rotates at the speed less than the synchronous speed. AC Induction Motor is known as the Asynchronous Motor. Synchronous motor does not have slip.
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.
How does a motor start?
When the supply is connected to the stator of a three-phase induction motor, a rotating magnetic field is produced, and the rotor begins rotating and the induction motor starts. At the time of starting, the motor slip is unity, and the starting current is very large.
What is the speed of synchronous motor?
Synchronous speed is the speed of rotation of the magnetic field in a rotary machine. An induction motor always runs at a speed less than synchronous speed. The rotating magnetic field which is produced in the stator will generate flux in the rotor which will make the rotor rotate.
