Why commutator is not used in AC motor?
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Why commutator is not used in AC motor?
Commutators are relatively inefficient, and also require periodic maintenance such as brush replacement. Therefore, commutated machines are declining in use, being replaced by alternating current (AC) machines, and in recent years by brushless DC motors which use semiconductor switches.
What does a rectifier do on a AC motor?
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation is performed by the inverter. The process is known as rectification, since it “straightens” the direction of current.
Why is a commutator used in a motor?
The commutator assures that the current from the generator always flows in one direction. 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.
Why is the DC motor preferred over AC motor?
D.C. motor is preferred over an A.C. motor when we need variable speed operation because As in DC series motor field winding and armature winding is in series. So whenever armature current changes field current also changes as they are same due to which its torque changes rapidly and we get a variable speed.
Does an AC generator have a commutator?
AC generator does not have commutators. DC generators have commutators to make the current flow in one direction only. AC generators have slip-rings.
What is the necessity of rectifier?
Using a rectifier in the power supply helps in converting AC to DC power supply. Bridge rectifiers are widely used for large appliances, where they are capable of converting high AC voltage to low DC voltage.
What is the purpose of a rectifier?
Essentially, a rectifier is an electrical device used to convert alternating current (AC) into direct current (DC) by allowing a current to flow through the device in one direction only. Diodes work like one-way valves within the rectifier to maintain this flow of current.
What is the difference between armature and commutator?
The combination of the commutator, ball bearings, winding & brushes is called an armature….Key Difference between Armature & Commutator.
| Armature | Commutator |
|---|---|
| It provides current to commutator from the core of the armature | It changes AC to DC & vice-versa |
| It is a set of coils arranged in the core | It is a set of segments |
What is the disadvantage of DC motor?
Disadvantages Of DC Motor DC motors have a high initial cost. Maintenance cost is high and increased operation due to the presence of brushes and commutator. Due to sparking at brush DC motors cannot operate in explosive and hazardous conditions.
What are the advantages and disadvantages of the DC motors?
DC Motor Advantages & Disadvantages
| Advantages | Disadvantages |
|---|---|
| Inexpensive controls for speed regulation | Cogging at speeds of less than 300 rpm |
| Generally a low-cost motor option | Significant power loss on full wave rectified voltage |
| Easily pairs with gear reducers | High starting torque can damage reducers |
What would be the problem if we do not use a commutator at all?
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.