What is speed torque characteristics of DC motor?
The torque in case of a dc series motor is proportional to the square of the armature current. This relation is parabolic in nature as shown in the figure. As load increases, armature current increases and torque produced increases proportional to the square of the armature current up to a particular limitation.
What are the characteristics of a DC series motor?
The characteristic curves of a DC series motor are those curves which show relationships between the following quantities.
- Torque and armature current (Ta/Ia characteristic).
- Speed and armature current (N/Ia characteristic)
- Speed and torque (N/Ta characteristic) It is also known as mechanical characteristic.
How do DC motors work PDF?
Working Principle of D.C. Series Motor The large current through the winding produces a strong magnetic field. This strong magnetic field gives high torque to the armature shaft, thus exerting the spinning action of the armature. Hence the motor starts rotating at its maximum speed in the beginning.
What is the unit of DC motor?
Operating principle of dc motors As stated in Unit 1, motors turn because of the interaction between two magnetic fields. This unit will discuss how these magnetic fields are produced in dc motors, and how magnetic fields induce voltage in dc generators.
What is speed torque characteristic?
Torque Speed Characteristic is the curve plotted between the torque and the speed of the induction motor. We have already discussed the torque of the induction motor in the topic Torque Equation of an Induction motor.
How the characteristic of DC series motor differs from DC shunt motor?
A series motor respond by decreasing its speed with small increase in current for a given load torque. A shunt motor holds its speed nearly constant with large increase in input current for same amount of load torque.
Which DC motor gives constant speed characteristics and how?
Hence, a DC shunt motor always maintains a constant speed. Under no load condition, the back emf becomes nearly equal to the applied voltage. Because the torque required to overcome the friction and the windage loss is very small, that is armature current Ia also small.
What type of DC motor has similar speed characteristics?
So from these 2 equations, we can conclude that Speed and Torque both has a linear relationship. This characteristics is similar to speed – Armature current characteristics. This curve shows that the speed almost remains constant through torque changes from no load to full load conditions.
How do DC motors control speed?
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.
What is the difference between AC and DC motor PDF?
DC motors are always self-starting in nature. In AC motors, the armature is stationary while the magnetic field rotates. In DC motors, the armature rotates but the magnetic field remains stationary. This motor has three input terminals.
What is a series DC motor?
A series DC motor connects the armature and field windings in series with a common D.C. power source. The motor speed varies as a non-linear function of load torque and armature current; current is common to both the stator and rotor yielding current squared (I^2) behavior.
What is the speed of DC motor?
DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.