Expression of speed and speed regulation of DC Motor with Handwritten Notes in PDF

Speed

The most conventional unit of measuring the speed of a motor is RPM. This stands for revolutions per minute, or the number of times the motor’s shaft will rotate in one minute.

Speed Of A DC Motor

Back emf E_b of a DC motor is nothing but the induced emf in armature conductors due to rotation of the armature in magnetic field. Thus, the magnitude of E_b can be given by EMF equation of a DC generator.
E_b = ^PØNZ/_60A
(where, P = no. of poles, Ø = flux/pole, N = speed in rpm, Z = no. of armature conductors, A = parallel paths)

E_b can also be given as,
E_b = V- I_aR_a

thus, from the above equations
N = ^E_b 60A/_PØZ

but, for a DC motor A, P and Z are constants

Therefore, N ∝ K ^E_b/_Ø          (where, K=constant)

This shows the speed of a dc motor is directly proportional to the back emf and inversely proportional to the flux per pole.

Speed Regulation of DC Motor

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

I hope the above Hindi video lecture and the handwritten note can help you understand the speed and speed regulation of DC Motor properly. Stay with us for more educational video lectures and handwritten notes with free job alerts as well.

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