How does a commutator change current direction?

In a generator the commutator picks off the current generated in the windings, reversing the direction of the current with each half turn, serving as a mechanical rectifier to convert the alternating current from the windings to unidirectional direct current in the external load circuit.

How is torque maintained in a DC motor?

The torque of the motor is proportional to the product of the armature current, the main pole flux(field) and a machine constant which is a function of the armature windings. This means that if the shunt field excitation is kept constant, the torque is dependent solely upon the armature current.

How does the commutator keep the coil rotating in one direction?

So the current in the coil becomes opposite. Thus the forces again reverse which makes the coil to continue it’s rotation along a single direction. So the commutator reverses the current in every half turn producing a steady torque and the armature coil rotates in a single direction.

What is the function of commutator in DC motor Mcq?

Commutator is used as mechanical rectifier in DC machines. It converts AC armature current in to DC current. Commutator is used to convert AC current into DC current.

What will happen if commutator is not used in a DC motor?

Well, without commutator, the machine will not develop a unidirectional torque and motoring action will not take place. In a DC motor, at the instant when armature coil passes through magnetic neutral axis, current in armature coil must reverse to maintain torque in the same direction.

Which direction of DC motor reverses current?

Each half turn of the armature causes the brushes to contact a new split ring, reversing the direction of current flow through the armature windings, which reverses the polarity of the electromagnetism produced in the armature.

Which part of DC motor is used to change the direction of current?

In a DC motor, the split rings help to change the direction of current through the coil after every half rotation. For this reason, it is also called split ring commutator. Current is induced when the armature of a generator rotates.

What affects the torque of a DC motor?

Apart from the current through the coil the torque depends on the magnetic field strength. Usually DC motors have permanent magnets ( most commonly used are AlNiCo or SmCo magnets), a higher grade or strength of permanent magnets (like NdFeB) will produce a much higher torque.

Why is torque proportional to current?

With a constant voltage, the amperage drawn directly represents the load. So, increasing the load, results in an increase in the amperage. Even if the increased torque results in a decrease in speed, the amperage will increase unless the speed reduction is inversely proportional to the increase in torque.

Does commutator reverse current?

A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced.

Does the coil continue to rotate when the current is off?

When you give the coil a spin, since one side of the wire is insulated, you break the circuit briefly, so the coil continues to rotate using its momentum. When the circuit is complete again, the magnetic field once again repels the coil, so it keeps spinning. The motor can continue to spin until the battery is dead!

What is the purpose of a commutator on a motor?

On DC and most AC motors the purpose of the commutator is to insure that the current flowing through the rotor windings is always in the same direction, and the proper coil on the rotor is energized in respect to the field coils.

What is a commutator on a coil?

Simply put, the commutator turns the coils on and off to control which direction the electromagnetic fields are pointing. On one side of the coil, the electricity should always flow “away,” and on the other side, electricity should always flow “towards.”

What is the use of commutation in DC machines?

Commutation in DC machines is the process by which the reversal of current takes place. In DC generator this process is used to convert the induced AC in the conductors to a DC output. In DC motors commutation is used to reverse the directions of DC current before being applied to the coils of the motor.

Why does an armature coil rotate in a single direction?

Thus the forces again reverse which makes the coil to continue it’s rotation along a single direction. So the commutator reverses the current in every half turn producing a steady torque and the armature coil rotates in a single direction. I explained up to my best.