The speed of a DC motor (N) is equal to: Therefore speed of the 3 types of DC motors – shunt, series and compound – can be controlled by changing the quantities on the right-hand side of the equation above. Hence the speed can be varied by changing: The terminal voltage of the armature, V.
How can the speed of a DC motor be controlled?
Thus, the speed of a DC motor can be controlled in three ways: By varying the supply voltage. By varying the flux, and by varying the current through the field winding. By varying the armature voltage, and by varying the armature resistance.
Which speed can be obtained from field control of DC shunt motor?
6. Which speeds can be obtained from field control of DC shunt motor? Explanation: Speeds greater than rated speeds can be obtained by lowering the flux of shunt field motor. Field cannot be made any stronger, it can only be weakened by this method.
How can I increase the speed of a DC shunt motor?
The speed of a D.C. shunt motor can be increased by
- A. Increasing the resistance in armature circuit.
- Increasing the resistance in field circuit.
- Reducing the resistance in the field circuit.
- Reducing the resistance in the armature circuit.
Which speed control methods offers below normal speed in DC shunt motor?
Shunt motor is a special type of DC motor which runs at a constant speed. But using field and armature rheostat control method we can make it more versatile. Field rheostat provides above normal speed and armature rheostat provides wide range of below normal speed.
What is the speed of dc motor?
DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.
What is base speed of dc motor?
The base speed of a DC motor is the speed attained by a motor at rated armature voltage, rated load current, and rate field current. The motor operates below base speed when the armature voltage is reduced. The torque of the shunt motor remains constant at below base speed.
Why DC shunt motor is constant speed?
If the load on the motor increases armature speed reduces and thereby cause a reduction in the back emf. Hence, when back emf decreases the armature current increases. … Hence, a DC shunt motor always maintains a constant speed. Under no load condition, the back emf becomes nearly equal to the applied voltage.
What are the 3 types of DC motors?
Main Types of DC Motors
- Permanent Magnet DC Motors. The permanent magnet motor uses a permanent magnet to create field flux. …
- Series DC Motors. In a series DC motor, the field is wound with a few turns of a large wire carrying the full armature current. …
- Shunt DC Motors. …
- Compound DC Motors.
What are types of speed control of shunt motor?
Speed control of Shunt motor
- Flux control method. It is already explained above that the speed of a dc motor is inversely proportional to the flux per pole. …
- Armature control method. …
- Voltage Control Method. …
- Flux control method. …
- Variable resistance in series with armature. …
- Series-parallel control.
What is the principle of DC shunt motor?
Construction and Working Principle
The working principle of a DC Shunt Motor is, whenever a DC motor is turned ON, then DC flows throughout stator as well as the rotor. This current flow will generate two fields namely pole as well as the armature.
What are the advantages of DC shunt motor?
Advantages of Dc shunt motor:
- The power supply of the DC motor is any way cheap.
- Shunt would motor able to runs at a predetermined speed.
- The speed of a dc shunt motor is sufficiently constant.
- Direct current machines can use for heavy industrial applications where the torque and speed wider range.
What will happen with increase in speed of dc motor?
What will happen, with the increase in speed of a DC motor? a) Back emf increase but line current falls. … So, with the increase in speed, the back emf also increases. Therefore, armature current is also decreased, in case of series motor, armature current is equal to the line or load current.
Which starter is used for DC shunt motor?
Three-point starter is used to start dc shunt motor | Electrical Machines.
Which DC motor is preferred for constant speed?
Explanation: Rotary compressor generally demand constant speed operation throughout the load. Sometimes, DC machines are not able to produce constant speed throughout the process hence, synchronous machine is used. 4.
What is the most common method used in varying the speed of a DC motor?
(5.10). This reduces the voltage available across the armature and hence the speed falls.By changing the value of variable resistance, any speed below the normal speed can be obtained. This is the most common method employed to control the speed of d.c. series motors.