How can a DC motor below base speed?
Speeds below the motor base speed are obtained by weakening the generator field. This, in turn, lowers the generator voltage supplying the DC motor armature.
How can the speed of a shunt DC motor be controlled?
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.
What is base speed of DC shunt motor?
Base speed is Hz multiplied by 60 then divides the result by half the number of poles. Rated speed is the base speed minus the slip at full rated load. An induction motor slows as it is loaded. 60 x 60 x 2 = 7,200 no-load rpm Ã· number of poles.
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.
How do you increase the speed of a DC motor?
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.
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 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.
Why DC shunt motor is started on no load?
For DC shunt motor the field resistance is high and armature resistance is low so the variation of flux is very less when rated voltage is applied to the motor and motor speed does not exceeds rated speed at no load. So we can start the DC shunt motor with no load.
What will happen if excitation of DC shunt motor is changed?
2. What will happen if excitation of DC shunt motor is changed? … Explanation: Speed of the DC motor obtained from speed equation is inversely proportional to flux produced by the field. So, reducing the field current flux produced by armature will decrease, and speed will increase.
Which starter is used for DC shunt motor?
Three-point starter is used to start dc shunt motor | Electrical Machines.
What will happen if DC shunt motor is connected across AC supply?
What will happen if DC shunt motor is connected across AC supply? Explanation: In case of parallel field connection, it won’t rotate at all and will start humming and will create vibrations, as a torque produced by positive and negative cycle will cancel out each other. DC motor will be heated up and it may burn.