What will happen to the back emf E of the motor?

What will happen to the back emf E of the motor?

The driving torque increases the speed of the motor which also increases their back emf. The high value of back emf decreases the armature current. The small magnitude of armature current develops less driving torque, which is equal to the load torque. And the motor will rotate uniformly at the new speed.

What happens if motor back emf is 0 no current flows?

So, if back emf is zero that means which tells us that either speed of the motor or field flux or both are zero. In other words, the motor is standstill because field flux is required for creating torque for rotation. So, if E=0, the supplied voltage equals to voltage drop against armature resistance.

What is the reason EMF is called back emf in case of DC motors?

When the armature of a DC Motor rotates, then the current carrying armature windings move through the magnetic field and as we know that when a current carrying conductor moves in magnetic field, then an emf is induced and the emf which is induced in the armature winding of the DC motor is called Back Emf.

What happens to the back emf if the speed of a DC shunt motor increases?

So, the back emf is directly proportional to speed. Hence, when the speed of a DC shunt motor is increased, then the back emf of the motor will increase.

Is back emf good or bad?

It’s kind of a good thing. Back EMF keeps current from going nuts. Pure resistance is kept low to keep heating down. After you’ve done that, you are relying on back EMF to keep your breakers un-popped and power components un-cratered.

What does back emf do?

A motor has coils turning inside magnetic fields, and a coil turning inside a magnetic field induces an emf. This emf, known as the back emf, acts against the applied voltage that’s causing the motor to spin in the first place, and reduces the current flowing through the coils of the motor.

What will happen if back emf?

If back emf of a dc motor vanishes suddenly, motor circuit will try to retain back emf by drawing more current from supply. If supplying unit didn’t trip down by this time, excess current in armature may heat up the armature and it may cause burning of armature winding.

What is the purpose of a back emf?

In motor control and robotics, back-EMF often refers most specifically to actually using the voltage generated by a spinning motor to infer the speed of the motor’s rotation, for use in better controlling the motor in specific ways.

What is the function of back emf?

What will happen if dc motor speed is increased?

From the equation. (3) we can say, speed is inversely proportional to armature current. Thus, when the speed of the dc motor is increased, the armature current will decrease.

Why is the speed of DC shunt motor dependent on back EMF?

In the case of DC motors Speed ∝ Back emf(Eb)/flux(φ). The field winding is connected across the armature. The resistance offered by the field is constant so the current is constant. Therefore the speed of the DC shunt motor depends on the back EMF.

What is the effect of back emf?

The presence of back emf makes the d.c. motor a self-regulating machine i.e., it makes the motor to draw as much armature current as is just sufficient to develop the torque required by the load.