Why Interpoles are used in dc motor? Inter poles in dc machines help to reduce armature reaction effects in the inter polar regions and their windings are connected in series with the armature so that its effect can vary with the armature current.
What is the role of Interpoles in DC motors?
Interpoles. Interpoles are designed in DC motors to overcome the effects of the armature reactance and the self-induction of the machine. Most shunt and compound DC motors over one-half horsepower have interpoles located 90 electrical degrees from the main poles.
What is the chief purpose of a dc motor starter?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
What will happen if the back EMF of a dc motor vanishes suddenly?
If back emf of a dc motor vanishes suddenly, motor circuit will try to retain back emf by drawing more current from supply. As the back emf vanishes zero, the whole supply voltage appears across armature and heavy current flows.
What are the factors that affect the speed of a dc motor?
Factors Affecting The Speed Of Dc Motor
- The applied voltage.
- The flux.
- The voltage across an armature.
What is the chief purpose of a DC motor starter?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
What is DC motor working principle?
A DC motor is an electrical machine which converts electrical energy into mechanical energy. The basic working principle of the DC motor is that whenever a current carrying conductor places in the magnetic field, it experiences a mechanical force.
What are the factors that affect the speed of a DC motor?
Factors Affecting The Speed Of Dc Motor
- The applied voltage.
- The flux.
- The voltage across an armature.
What is the chief advantage of DC motor?
The primary advantage of the DC motor is that it can develop constant torque over a wide speed application. Power supply is an important consideration in the application of DC motors. The most common way to provide DC voltage to a motor from an AC line is through the use of an electronic drive.
What are the applications of DC motor?
Application of DC Series motor
- Cranes.
- Air compressor.
- Lifts.
- Elevators.
- Winching system.
- Electric traction.
- Hair drier.
- Vacuum cleaner and in speed regulation application.
What is in a DC motor?
A DC motor consists of an stator, an armature, a rotor and a commutator with brushes. Opposite polarity between the two magnetic fields inside the motor cause it to turn. DC motors are the simplest type of motor and are used in household appliances, such as electric razors, and in electric windows in cars.
Why back EMF is used in DC motor?
When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.
What will happen to the back EMF of a DC motor if its speed will increase?
As the motor turns faster and faster, the back emf grows, always opposing the driving emf, and reduces the voltage across the coil and the amount of current it draws.
Which DC motor has maximum self loading property?
Which DC motor has got maximum self-loading property? Explanation: A differentially compound DC motor, flux reduces so sharply at small increase in load at higher values of load.
How can the speed of a DC motor be controlled?
Thus, the speed of a DC motor can control in three ways: By varying the flux, and by varying the current through field winding. By varying the armature voltage, and the armature resistance. Through the supply voltage.
What can increase the speed of a DC motor?
Increasing the speed can be achieved by increasing the supply frequency as the speed and frequency are directly proportional; however, there are two constraints. The first is the saturation of the magnetic circuit, but this issue can be significantly avoided by keeping the V/f ratio constant.
How can you reduce the speed of a DC motor?
Thus, the speed of a DC motor can be controlled in three ways:
- By varying the supply voltage.
- By varying the flux, and by varying the current through the field winding.
- By varying the armature voltage, and by varying the armature resistance.
What are characteristics of dc motor?
Generally, three characteristic curves are considered important for DC motors which are, (i) Torque vs. armature current, (ii) Speed vs. armature current and (iii) Speed vs. torque.
What are the advantages of DC motor?
Good speed control
DC motors offer highly controllable speed. By changing the armature or field voltage it’s possible to achieve wide speed variation and with this level of controllability, DC motors offer the precision required by a wide range of industry applications.
What is the equation of DC motors?
V = Eb + IaRa ….. (
The above relation is known as “Voltage Equation of the DC Motor”.
How do you change the speed of a DC motor?
Thus, the speed of a DC motor can be controlled in three ways: By varying the supply voltage. By varying the flux, and by varying the current through the field winding. By varying the armature voltage, and by varying the armature resistance.
What are the disadvantages of DC motor?
Disadvantages of DC motors
- High initial cost.
- Increased operation and maintenance cost due to the presence of commutator and brush gear.
- Cannot operate in explosive and hazard conditions due to sparking occur at brush (risk in commutation failure)
What controls the speed of a DC motor?
Thus, the speed of a DC motor can be controlled in three ways: By varying the supply voltage. By varying the flux, and by varying the current through the field winding. By varying the armature voltage, and by varying the armature resistance.
When would you use a DC motor?
Applications. DC motors are suitable for many applications – including conveyors, turntables and others for which adjustable speed and constant or low-speed torque are required. They also work well in dynamic braking and reversing applications, which are common in many industrial machines.
References
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