When A.C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much. Consequently, Shunt motor will not usually run on A.C Supply.
What will happen if dc series motor is connected across AC supply?
If a DC series motor is connected to an AC supply same current will flow through the series field and armature field after being rectified by the commutator. So, the machine will run but with high sparking at brush, poor pf, low speed and low efficiency. … If the field current increases, speed will decrease.
Can you power a DC motor with AC?
(1) AC motor cannot run on DC Supply because of most of AC motor like Single-Phase Induction Motors, Three Phase Induction Motors, Synchronous Motors need alternating flux, not static flux. As we know that only AC can produce alternating flux. So AC motor cannot run DC supply.
What will happen if a single phase supply is connected to an ordinary DC series motor?
The torque produced will be. of zero average value. pulsating and unidirectional.
What will happen if you reverse the power source polarities for a DC shunt motor?
Armature connection changed to give opposite direction of current in armature while maintaining field direction results in clockwise rotation. Reverse field polarity and armature polarity from middle diagram will result in the same clockwise direction of rotation.
What are the advantages of DC shunt motor?
Advantages of Dc shunt motor:
- The power supply of the DC motor is any way cheap.
- Shunt would motor able to runs at a predetermined speed.
- The speed of a dc shunt motor is sufficiently constant.
- Direct current machines can use for heavy industrial applications where the torque and speed wider range.
What will happen if excitation of DC shunt motor is changed?
2. What will happen if excitation of DC shunt motor is changed? … Explanation: Speed of the DC motor obtained from speed equation is inversely proportional to flux produced by the field. So, reducing the field current flux produced by armature will decrease, and speed will increase.
Are DC or AC motors cheaper?
However, DC motors are expensive to purchase and to maintain. In addition, over the past 10 years, AC drives have improved to the point where their speed control is far more precise, rivaling that of servo drives. What’s more, the AC motor and drive together often cost about the same price as the DC motor alone.
How can you tell if a motor is AC or DC?
Look for the stator core construction and rotor. If there is no commutator, then it is a AC motor. If there is a commutator and brushes, it may be either a DC motor or an AC commutator motor (Universal motor).
Whats better AC or DC motor?
Which Motor Is More Powerful: AC or DC? AC motors are generally considered to be more powerful than DC motors because they can generate higher torque by using a more powerful current. However, DC motors are typically more efficient and make better use of their input energy.
What is cogging and crawling?
The important characteristics normally shown by a squirrel cage induction motors are crawling and cogging. These characteristics are the result of improper functioning of the motor that means either motor is running at very slow speed or it is not taking the load.
Why is the DC motor preferred over AC motor?
DC motors have the advantage of: higher starting torque, quick starting and stopping, reversing, variable speeds with voltage input and they are easier and cheaper to control than AC. AC motor advantages include: lower power demand on start and minimal maintenance.
Which machine can not work on AC supply?
A transformer is a device which step-up or step-down the level of AC current or voltage without changing the primary (i.e. input source) frequency. Transformer only works on AC and can’t be operated on DC i.e. it has been designed to be operated only and only on alternating current and voltage.
How do you control the speed of a DC shunt motor?
Thus, there are three general methods of speed control of D.C. Motors.
- Resistance variation in the armature circuit: This method is called armature resistance control or Rheostat control.
- Variation of field flux Ф This method is called field flux control.
- Variation of the applied voltage.
What happens if generator rotates in reverse direction?
If you reverse the direction of rotation, the residual field won’t immediately change. However, the output voltage polarity will change and there will be a small reversed voltage at the output.
What is principle of DC shunt motor?
Construction and Working Principle
The working principle of a DC Shunt Motor is, whenever a DC motor is turned ON, then DC flows throughout stator as well as the rotor. This current flow will generate two fields namely pole as well as the armature.