Is line current and armature current same?

Field currents may be derived from the line also, but the current is much smaller so that to a first approximation, the armature current and the line current are the same.

What is the relationship between the armature current and motor speed by varying the field resistance?

By varying the armature circuit resistance, the current and flux both are affected. The voltage drop in the variable resistance reduces the applied voltage to the armature, and as a result, the speed of the motor is reduced.

What is meant by armature current?

In electrical engineering, an armature is the component of an electric motor which carries alternating Current. The armature windings conduct AC even on DC machines, due to the commutator action (which periodically reverses Current direction) or due to electronic commutation, as in brushless DC motors.

Why does the armature current decrease as the motor speed increases?

With a lower overall voltage across motor’s internal resistance as the motor turns faster, the current flowing into the motor decreases. The faster the motor spins the less current it draws.

What is GNA and MNA?

The geometrical neutral axis (GNA) is the axis that bisects the angle between the centre line of adjacent poles. The magnetic neutral axis (MNA) is the axis drawn perpendicular to the mean direction of the flux passing through the centre of the armature.

What is difference between armature and rotor?

It is located inside the stator and its objective is to rotate so that in turn the motor shaft or generator rotates. So basically, the rotor consists of a field magnet which rotates while the rotor remains stationary and on the other hand the armature carries current and is stationary and part of the stator.

What is field current and armature current?

The field of a machine is the part that generates the direct magnetic field. The current in the field does not alternate. The armature winding is that which generates or has an alternating voltage applied to it.

How do you increase the speed of a DC motor?

Thus, the speed of a DC motor can be controlled in three ways:

  1. By varying the supply voltage.
  2. By varying the flux, and by varying the current through the field winding.
  3. By varying the armature voltage, and by varying the armature resistance.

How do armatures work?

In the armature, an electromotive force is created by the relative motion of the armature and the field. When the machine or motor is used as a motor, this EMF opposes the armature current, and the armature converts electrical power to mechanical power in the form of torque, and transfers it via the shaft.

How are armatures made?

The core of the armature is made up of laminated thin metal plates instead of a single piece. The thickness of laminations depends on the supply frequency. It is approximately 0.5mm thick. The laminated silicon steel is used for the armature core to reduce the eddy current and hysteresis loss.

What is the relation between torque and armature current?

We know that torque is directly proportional to the product of armature current and field flux, Ta ∝ ɸ.

What happens when the speed of the DC motor increases its armature current?

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.