# Speed Regulation of DC Motor

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The speed regulation of DC motor is defined as the change in speed from no load to full load, expressed as a fraction or percentage of full load speed. If the load is applied to the DC motor, the speed of the motor decreases automatically. Thus to maintain the constant speed, the difference between no load and full load speed called as speed regulation of DC motor should be maintained very less.

On application of load the speed of a DC motor decreases gradually. This is not at all desirable. So the difference between no load and full load speed should be very less. The motor capable of maintaining a nearly constant speed for varying load is said to have good speed regulation i.e the difference between no load and full load speed is quite less.

# Speed Regulation of DC Motor

The speed regulation of a permanent magnet DC motor is good ranging from 10 – 15% whereas for DC shunt motor it is somewhat less than 10 %. DC series motor has poor value of regulation. In case of compound DC motor for DC cumulative compound the speed regulation is around 25 % while differential compound has its excellent value of 5 %.

The speed regulation is defined as the change in speed from no load to full load, expressed as a fraction or percentage of full load speed.
Therefore, as per definition per unit (p.u) speed regulation of DC motor is given as,

Similarly, percentage (%) speed regulation is given as,

A motor which has nearly constant speed at all load below full rated load, have good speed regulation.

## Speed of a DC Motor

The emf equation of DC motor is given by

Here,

• N = speed of rotation in rpm.
• P = number of poles.
• A = number of parallel paths.
• Z = total no. conductors in armature.

Hence, speed of a DC motor is directly proportional to emf of rotation (E) and inversely proportional to flux per pole (φ).

### Speed Regulation of DC Motor Conclusion

After going through the above portion of speed regulation of dc motor we can now establish what speed regulation of dc motor is. I hope you enjoy when reading this article, thank you.