Why are DC shunt motors not considered suitable?

DC shunt motors are not suitable for traction purpose, the reasons are given below: 1. The dc shunt motor is a constant speed motor and its speed-torque characteristic does not meet with the requirements of traction. Thus the torque developed is considerably affected by variation in supply voltage.

Can DC motors have variable speed?

A: In general if you don’t do anything special to it, a DC motor will have variable speed. The main factors are the DC voltage applied to the armature coil and the amount of torque load you are trying to drive. In order to make it into a constant speed DC motor you have to have some sort of electronic feedback.

What are the disadvantages of DC shunt motor?

Disadvantages of DC shunt motor:

• Dc motors are unreliable at low-speed operations.
• The size of Dc motors is large compared to alternative current motors.
• The installation of DC machines is expensive compare with other types of machines.

What are the applications of a DC shunt motor?

DC Shunt Motor Applications

• These motors are used wherever stable speed is required.
• This kind of DC motor can be used in Centrifugal Pumps, Lifts, Weaving Machine, Lathe Machines, Blowers, Fans, Conveyors, Spinning machines, etc.

Why DC motor has higher speed than shunt motor?

In a shunt wound DC motor, the armature (rotor) and field (stator) windings are connected in parallel. The net voltage increase causes the armature current to increase, which increases the motor torque. This additional motor torque increases speed enough to compensate for the slowdown that occurred due to loading.

Why DC series motor is suitable for traction?

DC series motor has develops high torque at low speeds, low torque at high speed, this is the basic requirement of traction unit. Commutating property of series motor is good so we get sparkles commutation. Torque is unaffected by variation in supply voltage. DC Series motor maintenance cost is less.

Which type of DC motor is used for variable speed control application?

4. Compound DC Motors. Compound DC motors or compound wound motors have both series and shunt field windings. These types of motors offer good starting torque, but they may have control problems in variable speed drive applications.

How can the speed of a DC motor be varied?

Thus, the speed of a DC motor can control in three ways: By varying the flux, and by varying the current through field winding. By varying the armature voltage, and the armature resistance. Through the supply voltage.

What is the disadvantage of shunt?

There are some disadvantages of a transistor shunt regulator are given below, It has poor efficiency for large load currents. It has high output impedance. The output DC voltage is not absolutely constant because both VBB and VZ voltages decrease with increase in room temperature.

What are the factors affecting the speed of a DC shunt motor?

The above equation shows that the speed depends upon the supply voltage V, the armature circuit resistance Ra, and the field flux Ф, which is produced by the field current. In practice, the variation of these three factors is used for speed control.

Which DC motor is preferred for constant speed?

DC shunt motor
Detailed Solution. DC shunt motor is almost constant speed motor and its torque varies linearly as the current.

How to control the speed of DC shunt motor by armature voltage control?

The set up for speed control of DC shunt motor by armature voltage control method is shown in the figure. A rheostat is connected in series with armature winding. By varying the value of R we can vary the voltage across the armature. We can use this technique to control motor speed below its rated value.

What is the difference between Series motor and shunt motor?

The speed characteristic of a shunt motor is different compared with a series motor. As a DC Shunt motor attains its complete speed, then the armature current can be directly connected to the motor load. When the load is extremely low within a shunt motor, then the armature current can also be low.

Which type of motor is best for variable speed application?

Until the late of the 1980s, when the variable frequency drive was not invented, dc motor was the best option for variable speed application. Series motor: D.C series motor have poor speed control and high starting torque. Speed control of this motor is possible by varying supply voltage.

Why shunt wound DC motor is called a constant flux motor?

But we know that the armature current is proportional to the field flux (Ish ∝ Φ). Thus the Φ remains more otherwise less stable, due to this reason; a shunt wound DC motor can be named as a constant flux motor. Whenever the DC shunt motor’s armature winding rotates within the magnetic field which is generated by the field winding.