Where approximate constant speed is to be maintained, which DC motor should be used?

A shunt motor is the appropriate choice for applications where approximately constant speed needs to be maintained. This is primarily due to the characteristics of the motor’s design. In a shunt motor, the field windings are connected in parallel (or shunt) with the armature windings. This configuration allows for a constant field strength, which helps maintain a relatively stable speed under varying load conditions.

As load increases, the armature current rises, which tends to decrease the speed; however, since the field current is only slightly affected by the armature current in a shunt motor, the field strength remains nearly constant. This results in a small variation in speed, making shunt motors ideal for situations requiring speed stability, such as driving fans, conveyors, or machine tools.

Additionally, shunt motors can achieve higher speeds compared to series motors and have better speed regulation. They are less sensitive to load variations, which aligns with the need for consistent speed maintenance. Other motor types, such as series and compound motors, do not provide the same level of speed stability under load changes. Specifically, series motors can increase in speed significantly with reduced load, which can lead to potential overspeed conditions. Thus, for maintaining an approximate constant speed, a shunt